Altair Feko 2022.1.1
Altair Feko Getting Started Guide Altair Feko 2022.1.1
Getting Started Guide
Updated: 08/12/2022
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Technical Support
Altair provides comprehensive software support via web FAQs, tutorials, training classes, telephone, and e-mail.
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Contents
Intellectual Property Rights Notice............................................................................ ii Technical Support...........................................................................................................vi
1 Creating a Rectangular Horn................................................................................... 12
1.1 Example Overview..................................................................................................... 13 1.2 Topics Discussed in this Example.................................................................................14 1.3 Example Prerequisites................................................................................................ 15 1.4 Feko Components and Workflow.................................................................................. 16 1.5 Introduction to CADFEKO............................................................................................17
1.5.1 Launching CADFEKO (Windows)........................................................................ 18 1.5.2 Launching CADFEKO (Linux)............................................................................. 18 1.5.3 Start Page......................................................................................................19 1.5.4 User Interface Layout...................................................................................... 20 1.5.5 Ribbon........................................................................................................... 23 1.5.6 Construction Tab............................................................................................. 24 1.5.7 Configuration Tab............................................................................................ 26 1.5.8 Notification Centre.......................................................................................... 27 1.5.9 Dialog Error Feedback..................................................................................... 28 1.5.10 Custom Keyboard Shortcut Settings.................................................................29 1.5.11 Custom Mouse Bindings................................................................................. 30 1.6 Introduction to POSTFEKO.......................................................................................... 31 1.6.1 Launching POSTFEKO...................................................................................... 32 1.6.2 User Interface Layout...................................................................................... 33 1.6.3 Validating the Model in POSTFEKO.................................................................... 36 1.6.4 Viewing the Near Field Results (3D).................................................................. 37 1.6.5 Viewing the Near Field Results (2D).................................................................. 39 1.6.6 Viewing the Far Field Results (3D).................................................................... 42 1.6.7 Viewing the Far Field Results (2D).................................................................... 43
2 Creating CADFEKO Models........................................................................................ 44
2.1 Example Overview..................................................................................................... 45 2.2 Topics Discussed in this Example.................................................................................46 2.3 Example Prerequisites................................................................................................ 47 2.4 Creating the Model in CADFEKO.................................................................................. 48
2.4.1 Launching CADFEKO (Windows)........................................................................ 49 2.4.2 Launching CADFEKO (Linux)............................................................................. 49 2.4.3 Building a Horn.............................................................................................. 50 2.4.4 Adding a Feed Pin to the Horn......................................................................... 64 2.4.5 Using Selection in the 3D View.........................................................................67 2.4.6 Creating an Aperture in a Face.........................................................................68
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2.4.7 Setting the Simulation Frequency......................................................................71 2.4.8 Saving the Model............................................................................................ 72 2.5 Final Remarks........................................................................................................... 73
3 GPS Patch Antenna.....................................................................................................74
3.1 Example Overview..................................................................................................... 75 3.2 Topics Discussed in Example....................................................................................... 76 3.3 Example Prerequisites................................................................................................ 77 3.4 Creating the Model in CADFEKO.................................................................................. 78
3.4.1 Launching CADFEKO (Windows)........................................................................ 79 3.4.2 Launching CADFEKO (Linux)............................................................................. 79 3.4.3 Activating Macro Recording of Model................................................................. 80 3.4.4 Setting the Model Unit.....................................................................................81 3.4.5 Adding Variables............................................................................................. 82 3.4.6 Defining a Dielectric Medium............................................................................ 85 3.4.7 Creating the Patch.......................................................................................... 86 3.4.8 Creating the Patch Substrate............................................................................89 3.4.9 Setting a Region to a Dielectric........................................................................ 90 3.4.10 Creating the Feed Pin.................................................................................... 92 3.4.11 Unioning the Geometry for Mesh Connectivity................................................... 93 3.4.12 Setting Faces to PEC..................................................................................... 94 3.4.13 Ports, Sources and Loads in CADFEKO............................................................. 96 3.4.14 Setting the Simulation Frequency.................................................................... 99 3.4.15 Modifying the Auto-Generated Mesh...............................................................100 3.4.16 Setting Local Mesh Sizes for Chamfered Edges................................................ 102 3.4.17 Adding a Far Field Request........................................................................... 104 3.4.18 Deactivating Macro Recording....................................................................... 105 3.4.19 Macro Recording of Example 3...................................................................... 106 3.4.20 Saving the Model........................................................................................ 109 3.5 Launching the Solver................................................................................................110 3.6 Viewing the Results in POSTFEKO.............................................................................. 111 3.6.1 Launching POSTFEKO.....................................................................................112 3.6.2 Viewing the Input Reflection Coefficient........................................................... 113 3.6.3 Viewing the Circular Components of the Far Field.............................................. 115 3.7 Final Remarks..........................................................................................................117
4 GPS Patch on Quadcopter....................................................................................... 118
4.1 Example Overview....................................................................................................119 4.2 Topics Discussed in Example..................................................................................... 120 4.3 Example Prerequisites...............................................................................................121 4.4 Creating the Model in CADFEKO................................................................................ 122
4.4.1 Launching CADFEKO (Windows)...................................................................... 123 4.4.2 Launching CADFEKO (Linux)........................................................................... 123 4.4.3 Setting the Model Unit................................................................................... 124
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4.4.4 Adding a Quadcopter from the Component Library.............................................125 4.4.5 Importing the GPS Patch................................................................................127 4.4.6 Defining a Workplane.....................................................................................128 4.4.7 Aligning the Patch and Quadcopter.................................................................. 131 4.4.8 Saving the Model.......................................................................................... 133 4.5 Launching the Solver................................................................................................134 4.6 Viewing the Results in POSTFEKO.............................................................................. 135 4.6.1 Using a Lua Script to Configure Graphs........................................................... 136 4.7 Final Remarks..........................................................................................................137
5 EMC Coupling..............................................................................................................138
5.1 Example Overview....................................................................................................139 5.2 Topics Discussed in Example..................................................................................... 140 5.3 Example Prerequisites...............................................................................................141 5.4 Creating the Model in CADFEKO................................................................................ 142
5.4.1 Launching CADFEKO (Windows)...................................................................... 143 5.4.2 Launching CADFEKO (Linux)........................................................................... 143 5.4.3 Creating a Monopole......................................................................................144 5.4.4 Creating a Transmission Line.......................................................................... 146 5.4.5 Defining an Infinite Ground Plane....................................................................147 5.4.6 Ports, Sources and Loads in CADFEKO............................................................. 148 5.4.7 Setting the Radiated Power Level.................................................................... 154 5.4.8 Setting the Simulation Frequency.................................................................... 155 5.4.9 Modifying the Auto-Generated Mesh................................................................ 156 5.4.10 Setting a Local Wire Radius for the Monopole................................................. 157 5.4.11 Saving the Model........................................................................................ 158 5.5 Launching the Solver................................................................................................159 5.6 Viewing the Results in POSTFEKO.............................................................................. 160 5.6.1 Launching POSTFEKO.....................................................................................161 5.7 Final Remarks..........................................................................................................165
6 Waveguide Power Divider....................................................................................... 166
6.1 Example Overview....................................................................................................167 6.2 Topics Discussed in Example..................................................................................... 168 6.3 Example Prerequisites...............................................................................................169 6.4 Creating the Model in CADFEKO................................................................................ 170
6.4.1 Launching CADFEKO (Windows)...................................................................... 171 6.4.2 Launching CADFEKO (Linux)........................................................................... 171 6.4.3 Setting the Model Unit................................................................................... 172 6.4.4 Adding Variables........................................................................................... 173 6.4.5 Creating the Power Dividing Pin...................................................................... 175 6.4.6 Creating the Waveguide Sections.................................................................... 176 6.4.7 Unioning the Geometry for Mesh Connectivity................................................... 178 6.4.8 Removing Redundant Faces............................................................................ 179
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6.4.9 Changing the Waveguide to a Shell (Hollow) Part.............................................. 180 6.4.10 Unioning the Waveguide and Power Dividing Pin.............................................. 181 6.4.11 Ports, Sources and Loads in CADFEKO........................................................... 182 6.4.12 Setting the Simulation Frequency.................................................................. 186 6.4.13 Adding a Near Field Request.........................................................................187 6.4.14 Setting Local Mesh Sizes for Waveguide Port Faces.......................................... 188 6.4.15 Saving the Model........................................................................................ 189 6.5 Launching the Solver................................................................................................190 6.6 Launching POSTFEKO............................................................................................... 191 6.6.1 Viewing the Input Reflection Coefficient........................................................... 192 6.6.2 Viewing the Near Fields................................................................................. 194 6.7 Final Remarks..........................................................................................................195
7 Optimisation of Bent Dipole and Plate................................................................ 196
7.1 Example Overview....................................................................................................197 7.2 Topics Discussed in this Example............................................................................... 198 7.3 Example Prerequisites...............................................................................................199 7.4 Creating the Model in CADFEKO................................................................................ 200
7.4.1 Launching CADFEKO (Windows)...................................................................... 201 7.4.2 Launching CADFEKO (Linux)........................................................................... 201 7.4.3 Adding Variables........................................................................................... 202 7.4.4 Creating the Bent Dipole................................................................................204 7.4.5 Creating the Plate......................................................................................... 206 7.4.6 Ports, Sources and Loads in CADFEKO............................................................. 207 7.4.7 Setting the Simulation Frequency.................................................................... 210 7.4.8 Requesting Far Fields.....................................................................................211 7.4.9 Defining an Optimisation Search..................................................................... 212 7.4.10 Specifying the Optimisation Parameters..........................................................213 7.4.11 Specifying the Far Field Goal........................................................................ 214 7.4.12 Modifying the Auto-Generated Mesh...............................................................216 7.4.13 Saving the Model........................................................................................ 217 7.5 Launching the Solver................................................................................................218 7.6 Launching POSTFEKO............................................................................................... 219 7.6.1 Setting Up POSTFEKO to View Optimisation Progress......................................... 220 7.6.2 Launching OPTFEKO.......................................................................................222 7.6.3 Viewing the Optimisation Results.....................................................................224 7.7 Closing Remarks...................................................................................................... 226
Index.................................................................................................................................227
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Creating a Rectangular Horn
1
1 Creating a Rectangular Horn
The example is intended for users with no or little experience with CADFEKO. It makes use of a completed rectangular horn model to familiarise yourself with model creation in CADFEKO and viewing the simulated results in POSTFEKO.
This chapter covers the following:
· 1.1 Example Overview (p. 13) · 1.2 Topics Discussed in this Example (p. 14) · 1.3 Example Prerequisites (p. 15) · 1.4 Feko Components and Workflow (p. 16) · 1.5 Introduction to CADFEKO (p. 17) · 1.6 Introduction to POSTFEKO (p. 31)
Altair Feko 2022.1.1 1 Creating a Rectangular Horn
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1.1 Example Overview
This example shows a completed rectangular horn model to familiarise yourself with the Feko components and workflow. The main elements and terminology in the CADFEKO and POSTFEKO graphical user interface are discussed.
Figure 1: Illustration of the horn antenna.
Tip: Watch the demo video before working through this example. The model in the demo video is similar to the horn model used in this example. Find the short demo video in the Altair installation directory, for example: Altair/2022.1/help/feko/videos/DemoExample.mp4 for Windows and Altair/2022.1/help/feko/videos/DemoExample.html for Linux.
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1.2 Topics Discussed in this Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· View the Feko general workflow. · Launch CADFEKO. · View the CADFEKO layout. · View the POSTFEKO layout. · View the far field results and near field results in POSTFEKO.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[3]: GS 1: Rectangular Horn Antenna
3. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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1.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 30 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[4] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
4. See the Troubleshooting section in the Appendix of the Feko User Guide for more details. Proprietary Information of Altair Engineering
Altair Feko 2022.1.1 1 Creating a Rectangular Horn
1.4 Feko Components and Workflow
View the typical workflow when working with the Feko components.
Use CADFEKO
Create / modify geometry
or add component from
component library
Set soluon sengs
Define frequency, sources and requests
Run Feko Solver
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Use POSTFEKO
Create new graph / display Add / view results Post-processing of results / scripng Export results / generate report
CADFEKO Create or modify the geometry (or model mesh) in CADFEKO, import geometry or mesh, or use a component from the component library. Apply solution settings, define the frequency, specify the required sources and request calculations.
When the frequency is specified or local mesh settings are applied, the automatic mesh algorithm calculates and creates the mesh to obtain a discretised representation of the geometry or model mesh. View the status of the model in the Notification centre. If any warnings or errors are given, correct the model before running the Solver.
Solver Run the Solver to calculate the specified output requests.
POSTFEKO Create a new graph or 3D view and add results of the requested calculations on a graph or 3D view. Results from graphs can be exported to data files or images for reporting or external post-processing. Reports can be created that export all the images to a single document or a custom report can be created by configuring a report template.
After viewing the results, it is often required to modify the model again in CADFEKO and then repeat the process until the design is complete.
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1.5 Introduction to CADFEKO
Use CADFEKO to configure a solver-ready input file for Solver simulations.
CADFEKO is the Feko component that allows you to create complex CAD geometry using primitive structures (for example, cuboids and polygons) and to perform Boolean operations (for example, union and subtract) on the geometry. Complex geometry models and mesh models can be imported or exported in a wide range of industry standard formats. Reduce development time by using a component from the list of antennas and platforms in the component library.
In CADFEKO, you can request multiple solution configurations, specify calculation requests as well as specify the solution settings for the model. If an optimisation search is required, you can specify the optimisation parameters and goals.
In CADFEKO, you can request multiple solution configurations, specify calculation requests as well as specify the solution settings for the model. If an optimisation search is required, you can specify the optimisation parameters and goals.
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1.5.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 2: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
1.5.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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1.5.3 Start Page
The Feko start page is displayed when starting a new instance (no models are loaded) of CADFEKO, EDITFEKO or POSTFEKO. The start page provides quick access to Create a new model, Open an existing model, and a list of Recent models.
Links to the documentation (in PDF format), introduction videos and website resources are available on the start page. Click the icon to launch the Feko help.
Figure 3: The CADFEKO start page.
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1.5.4 User Interface Layout
View the main elements and terminology in the CADFEKO graphical user interface (GUI).
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1. Quick access toolbar The quick access toolbar is a small toolbar that gives quick access to actions that are performed often. The actions available on the quick access toolbar are also available via the ribbon. The quick access toolbar includes: New, Open, Save, Undo and Redo.
2. Ribbon The ribbon is a command bar that groups similar actions in a series of tabs. The ribbon consists of the application menu, core tabs and contextual tab sets.
3. Configuration list The configuration list is a panel that displays all defined configurations in the model. A new model starts by default with a single standard configuration. The following configuration types are supported: Standard configuration, Multiport S-parameter configuration and Characteristic modes configuration.
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Tip: Multiple configurations allow you to perform efficient simulations using different configurations (different loads, sources, frequencies or power scaling) in a single model.
4. Model tree The model tree is a panel that organises the model-creation hierarchy and configurationspecific items of the model into two separate tabs at the top of the panel. A right-click context menu is available for all items in the model tree. Double-click on an item to open its properties. Predefined variables, named points, media, workplanes, field/current data, worksurfaces and cables are listed in both the Construction tab and the Configuration tab to provide quick access. a. Construction tab The Construction tab lists the model-creation hierarchy in a tree format.
Note: Select a geometry or mesh part on the Construction tab and in the details tree (5), modify its wire / edge / face / region properties, solution settings and custom mesh settings.
b. Configuration tab The Configuration tab lists the configuration-specific items in a tree format.
Note: Select a configuration in the configuration list (3) and view its configuration-specific items in the Configuration tab.
5. Details tree The details tree is a panel that displays the relevant wires, edges, faces and regions for the geometry or mesh part selected in the Construction tab (4). From the right-click context menu specify the properties for its wire, edge, face or region properties in the details tree. You can modify the selected item's local mesh size, material definition or coating or solution properties that are specific to the selection.
6. Status bar The status bar is a small toolbar that gives quick access to macro recording, general display settings, tools, selection method and type, snap settings and the model unit.
7. Model Status icon The Model Status icon shows the current status of the model in the Notification centre. The Notification centre can be hidden but the Model Status icon in the status bar will still indicate the current status of the model.
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Altair Feko 2022.1.1 1 Creating a Rectangular Horn
8. Notes view The notes view is a window where you can document model details. Add additional comments or information for future reference.
Tip: The notes view is hidden by default, but can be enabled. On the Home tab, in the Create view group, click the Notes icon.
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9. Notification centre The Notification centre performs computational electromagnetic model (CEM) validation and shows the status of the model. When problems in the model are detected, it is highlighted in the Notification centre with hyperlinks to the problematic entities.
10. 3D view The 3D view window displays the geometry and mesh as well as solution requests (for example, a far field request).
Tip: · Select the Construction tab (4.a) to view only CAD in the 3D view. · Select the Configuration tab (4.b) to view both CAD and solution requests in the 3D view.
11. Help The Help icon gives quick access to the Feko manuals.
Tip: Press F1 to access context-sensitive help.
12. Search bar The search bar is a single-line textbox that allows you to enter a keyword and search for relevant information in the GUI. Entering a keyword in the search bar will populate a dropdown list of actions as well as the location of the particular action on the ribbon or context menu. Clicking on an item in the list will execute the action.
13. Application launcher The application launcher toolbar is a small toolbar that gives quick access to other Feko components.
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1.5.5 Ribbon
The ribbon is a command bar that groups similar actions in a series of tabs.
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Figure 4: The ribbon in CADFEKO. 1. File menu
The File menu is the first item on the ribbon. The menu allows saving and loading of models, import and export options as well as giving access to application-wide settings and a recent file list. 2. Core tabs A tab that is always displayed on the ribbon, for example, the Home tab and Construct tab. The Home tab is the first tab on the ribbon and contains the most frequently used commands for quick access. 3. Contextual tab sets A tab that is only displayed in a specific context. For example, the Schematic contextual tab set contains the Network Schematic contextual tab. Contextual tabs appear and disappear as the selected items such as a view or item on a view, change. 4. Ribbon group A ribbon tab consists of groups that contain similar actions or commands. 5. Dialog launcher Click the dialog launcher to launch a dialog with additional and advanced settings that relate to that group. Most groups don't have dialog launcher buttons. Keytips A keytip is the keyboard shortcut for a button or tab that allows navigating the ribbon using a keyboard (without using a mouse). Press F10 to display the keytips. Type the indicated keytip to open the tab or perform the selected action.
Figure 5: An example of keytips.
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1.5.6 Construction Tab
The Construction tab contains the geometry and mesh representation of the current model in a tree structure. It also lists ports and the optimisation configuration. The tree contains a Definitions branch, Model branch and Optimisation branch.
Figure 6: The Construction tab in the model tree. Definitions Branch
The Definitions branch contains by default the predefined variables, named points, media, mesh settings, workplanes, field/current data, worksurfaces and cables. Model Branch The Model branch is mainly a visualisation of the geometry and mesh creation hierarchy. Where geometry or mesh objects are derived from existing ones, the original (parent) objects are removed from the top level of the model and listed as sub-levels (children) under the new object.
Note: The highest-level items in the Model are referred to as "parts".
For example, Cone1 and Cuboid1 (parent objects) were unioned and the result is that they have become children of the new object (Union1). Union1 is the highest-level item and referred to as a part.
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Figure 7: The Construction tab in the model tree showing the part, Union1.
The Model branch also contain the ports, meshing rules, cutplanes and solution settings.
Optimisation Branch The Optimisation branch contains the optimisation searches, associated masks, parameters and goal functions defined for the model.
Note: The Optimisation branch is only displayed if the model contains an optimisation search or mask.
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1.5.7 Configuration Tab
The Configuration tab contains the global and configuration-specific model settings and requests of the current model in tree form. The tree contains a Definitions branch, Global branch and Configuration specific branch.
Figure 8: The Configuration tab in the model tree. Definitions Branch
The Definitions branch contains by default the predefined variables, named points, media, mesh settings, workplanes, field/current data, work surfaces and cables. Global Branch The Global branch contains the global specific model settings. From the right-click context menu define solver settings, specify the global frequency, sources, loads, networks and power. Configuration specific Branch The Configuration specific branch contains configuration specific settings. From the rightclick context menu define requests per configuration, frequency per configuration, sources per configuration, loads per configuration and power per configuration.
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1.5.8 Notification Centre
The Notification centre performs computational electromagnetic model (CEM) validation and shows the status of the model and notifications.
The Notification centre lets you stay informed of the model status at all times. When problems in the model are detected, it is highlighted in the Notification centre with hyperlinks to the problematic entities.
The Notification centre can be hidden but the Model Status icon in the status bar will still indicate the current status of the model.
Figure 9: The Notification centre in CADFEKO. Note the Model Status icon at the bottom that shows the current status of the model.
Show or hide the Notification centre using one of the following workflows: · Click the Model Status icon in the status bar. · Drag the splitter from the right edge of the application to open the pane. To close, drag the splitter all the way to the right. · On the Home, in the Validate group, click the Model Status icon.
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1.5.9 Dialog Error Feedback
CADFEKO provides error feedback for dialogs by showing a soft message bubble when validation fails on a dialog.
Click the icon to show or hide the message bubble or click elsewhere in CADFEKO to hide the message bubble. The error feedback is also shown per tab when the validation fails on a multi-tab dialog.
Figure 10: The soft message bubble indicating that an undefined variable was used on the Geometry tab of the Create Rectangle dialog.
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1.5.10 Custom Keyboard Shortcut Settings
CADFEKO provides default keyboard shortcuts. To better fit your workflow and work style, you can reassign keyboard shortcuts to different commands. To reassign mouse buttons, click the Application menu button. On the application menu panel, click Settings > Keyboard Shortcut Settings.
Figure 11: The Keyboard Shortcut Settings dialog. For example, to change the shortcut key for the undo command, on the Keyboard Shortcut Settings dialog, click in the CurrentKeySequence column and enter the shortcut key that suits your work style.
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1.5.11 Custom Mouse Bindings
CADFEKO provides default commands for all the mouse buttons. To better fit your workflow and work style, you can reassign mouse buttons to different commands. To reassign mouse buttons, click the Application menu button. On the application menu panel, click Settings > Mouse Binding Settings.
Figure 12: The Mouse Binding Settings dialog. For example, to reverse the mouse wheel direction to better suit your workflow, on the Mouse Bindings dialog, click Click to Configure. On the Zoom dialog, select the Invert check box.
Figure 13: The Zoom dialog. Proprietary Information of Altair Engineering
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1.6 Introduction to POSTFEKO
Use POSTFEKO to validate meshed geometry and analyse and post-process results.
POSTFEKO is the component that allows you to verify that your model is constructed and configured correctly before starting a simulation and analyse the results after the simulation completes. The POSTFEKO component is particularly useful to verify models created using EDITFEKO, but it is just as relevant for CADFEKO model verification.
Result post-processing and analysis is the primary function of POSTFEKO. Once a model has been simulated, POSTFEKO can be used to display and review the results. It is easy to load multiple models in a single session and compare them on 3D views, Cartesian graphs, Smith charts, polar graphs and surface graphs. Various measurement and other data formats are supported for comparison to the simulated results. A powerful scripting interface makes it easy to post-process results, automate repetitive tasks and create plug-in extensions that customise the interface and experience.
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1.6.1 Launching POSTFEKO
Open POSTFEKO from within CADFEKO. Use one of the following workflows to launch POSTFEKO:
· On the Solve/Run tab, in the Run/Launch group, click the
POSTFEKO icon.
· On the application launcher toolbar, click the POSTFEKO icon in the
group.
· Press Alt+3 to use the keyboard shortcut.
POSTFEKO opens by default with a single 3D view containing the model geometry.
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1.6.2 User Interface Layout
View the main elements and terminology in the POSTFEKO graphical user interface (GUI).
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1. Quick access toolbar The quick access toolbar is a small toolbar that gives quick access to actions that are performed often. The actions available on the quick access toolbar are also available via the ribbon. The quick access toolbar includes: New project, Open project, Save project, Undo and Redo.
2. Ribbon The ribbon is a command bar that groups similar actions in a series of tabs. The ribbon consists of the application menu, core tabs and contextual tab sets.
3. Project browser The project browser is a panel that lists the models loaded in the current project, imported data, stored data and scripted data.
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Tip: Collapse the project browser to expand the 3D view. On the View tab, in the Show group, click the Project icon.
4. Model browser The model browser is a panel that organises the model information of the selected model in the project browser (3), into two separate tabs. Model tab The Model tab lists the model information and results for the selected model. Results tab The Results tab lists the results and solution information.
5. Details browser The details browser is a panel that shows in-depth detail for the selected item in the model browser (4).
Tip: View the solution information for the selected model. On the model browser, click Solution information to view:
· memory per process · total CPU-time · total runtime.
6. Status bar The status bar is a small toolbar that gives quick access to general display settings, tools, and graph cursor settings.
7. 3D view/2D graphs 3D view The 3D view displays the geometry, mesh, solution settings as well as 3D results. 2D graphs The 2D graphs display the 2D results on either a Cartesian graph, polar graph, Smith chart or Cartesian surface graph.
Tip: · Re-order the window tabs by simply dragging the tab to the desired location. · Rename the window tab by using the right-click context menu and selecting Rename.
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8. Result palette The result palette is a panel that gives access to options that control the data in the 3D view or 2D graph for the relevant result type. For example, 3D far field data allows the phi cut plot type and gain in dB to be specified.
9. Help The Help icon gives quick access to the Feko manuals.
Tip: Press F1 to access context-sensitive help.
10. Search bar The search bar is a single-line textbox that allows you to enter a keyword and search for relevant information in the GUI. Entering a keyword in the search bar will populate a dropdown list of actions as well as the location of the particular action on the ribbon or context menu. Clicking on an item in the list will execute the action.
11. Application launcher The application launcher toolbar is a small toolbar that gives quick access to other Feko components.
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1.6.3 Validating the Model in POSTFEKO
View the model using visualisation tools in POSTFEKO to confirm the model was created as intended. Confirm the horn model is open in the 3D view.
1. Enable the mesh edges of the model. a) On the 3D View contextual tabs set, on the Mesh tab, in the Visibility group, click the Metal icon. From the drop-down list, select the Edges check box.
2. Zoom to extents of the 3D view using one of the following workflows: · On the View tab, in the Zoom group, click the Zoom to Extents icon. · Press F5 to use the keyboard shortcut.
3. Enable tick marks on the axes. a) On the 3D View contextual tabs set, on the Display tab, in the Axes group, click the Tick Marks icon.
4. Use the distance measurement tool to validate the dimensions of the horn. a) On the 3D View contextual tabs set, on the Mesh tab, in the Tools group, click the Measure Distance icon. b) On the Measure Distance dialog, ensure that the Point1 field is active. c) In the 3D view, press Ctrl+Shift+left click on the first point. d) Repeat Step 4.c for the second point.
Figure 14: The Measure distance dialog showing the distance between two points. e) Click Close the close the dialog.
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1.6.4 Viewing the Near Field Results (3D)
View the near field results in the 3D view and add a legend and contours. 1. Add the near field data to the 3D view. a) On the Home tab, in the Add results group, click the Near Fields icon. From the dropdown list, select NearField1.
Figure 15: Section of the ribbon showing the Add results group.
2. View the magnitude of the Ey component of the field. a) On the result palette, in the Quantity, clear the X check box and the Z check box.
Figure 16: The Quantity panel in the result palette.
3. View the electric field in dB. a) On the result palette, in the Quantity panel, select the dB check box.
4. Add a legend to the 3D view (top left). a) On the 3D View contextual tabs set, on the Display tab, in the Legends group, click the Top left icon. From the drop-down list select NearFields.
5. Add contours to the near field result. a) On the 3D View contextual tabs set, on the Result tab, on the Contours group, click the Show contours icon.
6. Specify the number of contours for the near field. a) On the 3D View contextual tabs set, on the Result tab, in the Contours group, click the Position icon. Click Number of contours and set its value to 11.
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Figure 17: The Contour positions dialog. b) Click OK to close the dialog.
Figure 18: The near field results with contours.
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1.6.5 Viewing the Near Field Results (2D)
Create a new Cartesian graph. Create two near field traces and compare the Ey and Ex components of the near field along the X direction.
1. Create a new Cartesian graph. a) On the Home tab, in the Create new display group, click the Cartesian icon.
2. Add the near field result to the Cartesian graph. a) On the Home tab, in the Add results group, click the Near Fields icon. From the dropdown list, select NearField1.
3. View the near field along the X direction. a) On the result palette, in the Slice panel, make the following changes: · From the Independent axis (Horizontal) list, select X position. · From the Frequency list, select 1.645 GHz. · From the Y position list, select 100 mm. · From the Z position list, select 460 mm.
Figure 19: The Slice panel in the result palette.
4. View the magnitude of the Ey component of the field. a) On the result palette, in the Quantity panel, clear the X check box and the Z check box.
Figure 20: The Slice and part of the Quantity panels in the result palette. 5. Add a second trace to the Cartesian graph by duplicating the NearField1 trace.
a) On the Trace tab, in the Manage group, click the Duplicate trace icon. A second trace, NearField1_1, is created.
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6. View the magnitude of the Ex component of the field. a) On the result palette, select the NearField1_1 trace. b) On the result palette, in the Quantity panel, select the X check box and clear the Y check box.
7. Set the vertical axis to dB. a) In the result palette, select both traces (NearField1 and NearField1_1). b) In the Quantity panel, select the dB check box.
8. Modify the minimum and maximum values for the vertical axis. a) On the Cartesian context tab, on the Display tab, on the Axes group, click the Axis settings icon. b) On the Axis settings (Cartesian graph) dialog, select the Vertical tab. c) Clear the Automatically determine the grid range check box. d) In the Maximum value field, enter a value of 40. e) In the Minimum value field, enter a value of -20.
Figure 21: The Axis settings (Cartesian graph) dialog. f) Click OK to close the dialog.
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Figure 22: The Ey and Ex components of the near field along the X direction.
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1.6.6 Viewing the Far Field Results (3D)
View the far field results in the 3D view. 1. Select the 3D view window. 2. Add the far field result to the 3D view. a) On the Home tab, in the Add results group, click the Far Field Source icon. From the drop-down list, select FarField1. 3. Hide the near field result still displayed in the 3D view. a) In the result palette, on the Traces panel, click the "eye" icon next to NearField1.
Figure 23: An open "eye" icon indicates that the trace is shown.
Figure 24: A closed "eye" icon indicates that the trace is hidden.
4. Add an annotation to the far field. a) Add an annotation to the desired location by pressing Ctrl+Shift+left click.
5. View the fields in dB. a) On the result palette, in the Quantity panel, select the dB check box.
6. Change the size of the far field compared to the geometry. a) On the 3D View contextual tabs set, on the Result tab, in the Rendering group, click the Size icon. From the drop-down list, select Custom. b) On the Specify dialog, set the size as 70%.
Figure 25: The 3D far field result. c) Click OK to specify the size of the far field and to close the dialog.
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1.6.7 Viewing the Far Field Results (2D)
View the far field results on a polar graph.
Note: Since a full 3D set of data was requested for this example, 2D cuts can be extracted.
1. Create a new polar graph. a) On the Home tab, in the Create new display group, click the
Polar icon.
2. Add the far field result to the polar graph. a) On the Home tab, in the Add results group, click the Far Field Source icon. From the drop-down list, select FarField1.
3. View the far field gain plotted in the YZ plane. a) On the result palette, in the Slice panel, make the following changes: · From the Independent axis (Angular) drop-down list, select Theta (wrapped). · From the Frequency drop-down list, select 1.645 GHz. · From the Phi drop-down list, select 90 deg (wrapped).
4. On the result palette, in quantity panel panel, select the dB check box.
Figure 26: The far field results on a polar graph. Proprietary Information of Altair Engineering
Creating CADFEKO Models
2
2 Creating CADFEKO Models
The example is intended for users with no or little experience with CADFEKO. This example is not an example intended for simulation, but rather to familiarise yourself with model creation in CADFEKO.
This chapter covers the following:
· 2.1 Example Overview (p. 45) · 2.2 Topics Discussed in this Example (p. 46) · 2.3 Example Prerequisites (p. 47) · 2.4 Creating the Model in CADFEKO (p. 48) · 2.5 Final Remarks (p. 73)
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2.1 Example Overview
Create a simple model using basic geometry and transformations to familiarise yourself with model creation in CADFEKO.
Figure 27: Illustration of the geometry created in this example.
Note: · The example does not use the fastest or most effective way to create geometry, but instead it highlights a subset of tools available in CADFEKO to create complicated geometrical structures.
Note: · This example is not intended for running the Solver. No electromagnetic solution is performed and no results are presented.
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2.2 Topics Discussed in this Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· CADFEKO Launch CADFEKO. Define variables to create a parametric model. Add a custom workplane. Create a rectangle. Create a line. Create a cuboid by sweeping the rectangle along the line. Create a flare. Union the flare and cuboid to ensure the parts are electrically connected. Remove a redundant face in the flare to create a horn. Add a feed pin to the line. Use automatic selection in the 3D view. Create an ellipse and subtract the shape from the cuboid face to create a hole.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[5]: GS 2: Model Construction
5. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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2.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 40 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[6] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
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2.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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2.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 28: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
2.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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2.4.3 Building a Horn
Learn to create variables, workplanes and primitive shapes. Continue by combining these basic entities and modifying their properties.
Note: To demonstrate the path sweep tool, the cuboid in this example is constructed using a rectangle and the path sweep tool.
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Adding Variables
Define variables to create a parametric model.
A model is parametric when it is created using variable expressions. When a variable expression is modified, any items dependent on that variable are re-evaluated and automatically updated. It is the recommended construction method when creating a model, but not compulsory.
Defined variables are stored as part of the model in the .cfx file.
1. Open the Create Variable dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Add Variable icon.
· On the model tree, a right-click context menu is available on Variables. From the list, select Add Variable.
Figure 29: The model tree (Construction tab). · On the model tree, click the icon. From the drop-down list, select Add Variable.
Figure 30: The drop-down list available in the model tree. · Press # to use the keyboard shortcut. Proprietary Information of Altair Engineering
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2. Create the following variables:
Name Width Length BottomDepth BottomWidth FlareLength TopWidth TopDepth
Expression 1 1 1 1 1 2 2
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Comment [Optional] Width of rectangle. Length of rectangle. Bottom depth of flare. Bottom width of flare. Length of flare. Top width of flare. Top depth of flare.
Figure 31: The Create Variable dialog.
Tip: · Click Add to keep the Create Variable dialog open and add more variables. · Click Create to add a variable and close the Create Variable dialog.
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Defining a Workplane
Define a workplane to create an oblique plane. Workplanes simplify the process of creating geometry on oblique planes in comparison to using transforms. The use of workplanes during construction is not compulsory, but is a more efficient method for creating geometry. For this example you will create a custom workplane and set as the default workplane.
Note: A workplane can be defined relative to another workplane.
1. Open the Create Workplane dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Add Workplane icon.
· On the model tree, a right-click context menu is available on the Workplanes group. Select Add Workplane from the drop-down list.
Figure 32: The Add Workplane group is available on both the Construct and Configuration tabs in the model tree.
· On the model tree, click the icon. From the drop-down list, select Add Workplane. · Press F9 to use the keyboard shortcut. 2. On the Create Workplane dialog, from the drop-down list, select Global YZ. 3. Use the default workplane label, Workplane1.
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Figure 33: The Create Workplane dialog. 4. Click Create to create the workplane and to close the dialog. The default workplane is used when creating new geometry primitives. For this example, set the new workplane as the default workplane. 5. In the model tree, select Workplane1.
a) From the right-click context menu, select Set as default.
Figure 34: The right-click context menu options for workplanes.
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Note: The current default workplane is indicated by the text, [Default].
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Creating a Rectangle
Create a rectangle to be used in the construction of the horn. 1. On the Construct tab, in the Create Surface group, click the
Rectangle icon.
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Figure 35: The Create Rectangle dialog.
Note: Default values are used on geometry creation dialogs to allow a preview in the 3D view. You may change the values as required.
Tip: An active field allowing point-entry is indicated by a yellow outline. Point-entry allows a variable or named points to be entered by pressing Ctrl+Shift+left click on a variable or named point in the model tree. 2. Create a rectangle using the Base centre, width, depth definition method. a) Use the following dimensions: · Base centre (C): (0, 0, 0) · Width (W): 1 · Depth (D): 1 3. Click Create to create the rectangle and to close the dialog.
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Figure 36: The rectangle created using Workplane1.
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Creating a Line
Create a line to be used in the construction of the horn. This line will be used to create a cuboid by sweeping the rectangle along the line.
1. On the Construct tab, in the Create Curve group, click the Line icon.
2. On the Create line dialog, enter the start point and end point for the line. · Start point: (0, 0, 0) · End point: (0, 0, 1)
Figure 37: The Create Line dialog. 3. Click Create to create the line and to close the dialog.
Figure 38: The rectangle and line created using Workplane1. Proprietary Information of Altair Engineering
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Creating a Cuboid by Sweeping a Rectangle along a Line
Create a cuboid by sweeping the rectangle along a line (path).
Tip: For demonstrative purposes, a rectangle is swept along a path to create a cuboid. The preferred method to create a cuboid is to make use of the cuboid tool. 1. In the model tree, select Rectangle1.
Note: Selecting Rectangle1 in the model tree enables Path Sweep on the ribbon.
2. On the Construct tab, in the Extend group, click the Path Sweep icon.
Figure 39: The Path Sweep dialog. 3. In the model tree, click Line1 to use as path. 4. On the Path Sweep dialog, use the default values. 5. Click Create to create the path sweep and to close the dialog.
Figure 40: The rectangle swept along a path (line) to create a cuboid. Proprietary Information of Altair Engineering
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Creating a Flare
Create a flare primitive to be used in the construction of the horn.
1. On the Construct tab, in the Create Solid group, click the Flare icon. 2. Create the flare using the Base centre, width, depth, height, top width, top depth method.
Figure 41: The Create Flare dialog. 3. Specify the flare dimensions using one of the following workflows:
· Add the defined variables manually. · Select a field on the Create Flare dialog and use point-entry to enter the values.
Note: An active field allowing point-entry is indicated by a yellow outline. Point-entry allows a variable or named points to be entered by pressing Ctrl+Shift+left click on a variable or named point in the model tree.
Use the following dimensions: · Base centre (C): (0, 0, 0) · Bottom width (Wb): BottomWidth · Bottom depth (Db): BottomDepth
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· Height (H): -FlareLength · Top width (Wt): TopWidth · Top depth (Dt): TopDepth
Tip: Parametric models are the preferred construction method. A parametric model updates automatically when updating a defined variable. Alternatively, use values instead of defined variables.
4. View the preview of the flare in the 3D view. Confirm that the model looks correct.
Figure 42: The preview of the flare is indicated in green. 5. Click Create to create the flare and to close the dialog.
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Creating a Union of the Flare and Cuboid
Union the flare and cuboid to create the horn.
Note: The union operation is used to define connectivity between parts.
Parts that touch, but are not unioned, are not considered to be physically connected and will result in an incorrect mesh.
1. In the model tree, select the flare and the cuboid (PathSweep1).
Figure 43: The Construction tab in the model tree showing the selected Flare1 and PathSweep1.
2. Union using one of the following workflows: · On the Construct tab, in the Modify group, click the · Press U to use the keyboard shortcut.
Union icon.
Figure 44: The Construction tab in the model tree showing the unioned part, Union1.
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Removing Redundant Geometry Faces
Delete the redundant faces in the geometry to create a horn. 1. In the model tree, select Union1. 2. In the details tree, under Faces, go through the list of faces. For each face, click on face until only Face13 and Face14 are displayed. a) Select Face13 and Face14.
to hide the
Figure 45: Select the two redundant faces. b) From the right-click context menu, click Delete.
Note: Deleting one of a regions's enclosing faces, removes the PEC region. c) Select any of the remaining faces and from the right-click context menu, click Show All.
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2.4.4 Adding a Feed Pin to the Horn
Add a wire feed to the model. As this example is only for demonstration purposes, this example does not cover the adding of a port or source to the wire feed.
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Creating the Feed Wire
Create a wire feed for the model. 1. On the Construct tab, in the Create Curve group, click the
Line icon.
2. On the Create Line dialog, click the Workplane tab. a) On the Workplane tab, select Custom workplane. b) Under Origin, click on X field to make point-entry active (indicated by a yellow outline).
3. Press Ctrl+Shift while moving the mouse cursor over the bottom face centre of the cuboid.
Note: The circles with a black outline indicate special snapping points. The red outline indicates the position of the mouse cursor.
Use snapping points to snap the workplane to an object. Although only special snapping points are indicated, you can snap to any point in the 3D view.
4. Press Ctrl+Shift+left click to snap the workplane to the bottom face centre of the cuboid. 5. On the Create Line dialog, click the Geometry tab.
a) Create a line. · Start point: (0, 0, 0) · End point: (0, 0, 0.25) · Label: Feed
6. Click Create to create the line and to close the dialog.
Figure 47: The feed wire is selected (highlighted in yellow).
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Unioning the Feed Wire and Horn
Union the feed wire and horn to ensure mesh connectivity and a correct mesh. 1. In the model tree, expand Union1. 2. In the model tree, select Feed and drag it to below Union1. 3. From the right-click context menu, select Move in. 4. View the model tree and confirm that it is correct.
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Figure 48: Union by dragging as item into a union in the model tree.
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2.4.5 Using Selection in the 3D View
Use the selection type tool to highlight an element in the 3D view.
The following steps are not required for constructing the model, but it illustrates how selection works in CADFEKO.
1. Move the mouse cursor to one of the faces on the inside of the flare. 2. Click on a face.
Figure 49: The part is selected and highlighted in yellow. 3. Click again on the face.
Figure 50: The face is selected and highlighted in yellow. Note: The default selection method (Auto) cycles through the applicable selection types when repeatedly clicking on the model. The first click selected the part. The second click selected the face. 4. Change the selection type using one of the following workflows: · On the Tools tab, in the Selection group, click the Selection Type icon. · On the status bar, click Selection Type icon. Select the required selection type from the list.
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2.4.6 Creating an Aperture in a Face
Create an aperture (hole) in a face or region by using the subtract tool. Create the geometry to be removed and subtract it from the target part. The target is the part that is reduced by cutting away a section of the part.
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Creating and Placing the Ellipse
Create an ellipse to subtract from the horn. The ellipse is placed on the face of the horn. 1. On the Construct tab, in the Create Surface group, click the Ellipse icon.
2. On the Create Ellipse dialog (Geometry tab), create an ellipse using the following dimensions: · Centre point (C): (0, 0, 0) · Radius (Ru): 0.3 · Radius (Rv): 0.2
3. On the Create Ellipse dialog, click the Workplane tab. a) On the Workplane tab, select Custom workplane. b) Under Origin, click on X field to make point-entry active (indicated by a yellow outline). c) Move the mouse cursor over the flare while holding down Ctrl+Shift until the local workplane is orientated as displayed in the image.
Figure 51: The placement of the ellipse on the horn. Note: The history of from where the mouse cursor was moved to the face centre, affects the orientation of the workplane. 4. Click Create to create the ellipse and to close the dialog.
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Subtracting the Ellipse from the Horn
The ellipse is subtracted from the horn to create a hole. 1. In the model tree, select Ellipse1. 2. Subtract using one of the following workflows: · On the Construct tab, in the Modify group, click the
Subtract From icon.
· On the model tree, a right-click context menu is available on the primitive. From the list select Apply > Subtract From.
Figure 52: The ellipse was subtracted from the horn. 3. In the model tree, select Union1.
Note: The T in the model tree indicates the target (object that was subtracted from).
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2.4.7 Setting the Simulation Frequency
Specify the frequency range of interest. For this example, a single frequency point is used. 1. On the Source/Load tab, in the Settings group, click the Frequency icon. 2. In the Frequency (Hz) field, enter 1e9.
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Figure 53: The Solution Frequency dialog. 3. Click OK to set the frequency and to close the dialog.
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2.4.8 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Model_creation.cfx. 3. Click Save to close the dialog.
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2.5 Final Remarks
This example showed aspects of model creation in CADFEKO.
Important: This example is not an example intended for simulation, but rather an introductory example that illustrates the power of CADFEKO when creating complex models.
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GPS Patch Antenna
3
3 GPS Patch Antenna
The example considers a left-handed circular polarised GPS patch antenna on a finite substrate.
This chapter covers the following:
· 3.1 Example Overview (p. 75) · 3.2 Topics Discussed in Example (p. 76) · 3.3 Example Prerequisites (p. 77) · 3.4 Creating the Model in CADFEKO (p. 78) · 3.5 Launching the Solver (p. 110) · 3.6 Viewing the Results in POSTFEKO (p. 111) · 3.7 Final Remarks (p. 117)
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3.1 Example Overview
Calculate the input reflection coefficient and circular components of a left-handed circular polarised GPS patch antenna on a finite substrate close to 1.57 GHz.
Figure 54: The chamfered GPS patch antenna on a finite substrate.
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3.2 Topics Discussed in Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· CADFEKO Activate macro recording of a model. Changing the model unit. Create and group variables. Create a dielectric. Create geometry (polygon, cuboid and line). Set the region of a cuboid to dielectric. Set the faces of a dielectric cuboid to PEC[7]. Add a voltage source to a wire segment. Modify the auto-generated mesh. Add a far field request. Deactivate macro recording and run the resulting Feko Lua script. Run the Solver.
· POSTFEKO View the input reflection coefficient on a Cartesian graph. View the left-hand and right-hand circular components of the far field on a Cartesian graph.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[8]: GS 3: GPS Patch Antenna
7. perfect electric conductor 8. The application macro library is located on the Home tab, in the Scripting group. Click the
Application Macro icon and from the drop-down list, select Getting Started Guide.
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3.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 40 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[9] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
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3.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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3.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 55: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
3.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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3.4.3 Activating Macro Recording of Model
Use macro recording to record actions in a script. Play the script back to automate the process or view the script to learn the Lua-based scripting language by example. Macro recording allows you to perform repetitive actions faster and with less effort.
Note: This step is optional when creating a model in CADFEKO but it is included in this example to highlight the functionality.
Activate macro recording using one of the following workflows: · On the Home tab, in the Scripting group, click the Record Macro icon. · Click the icon in the status bar.
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3.4.4 Setting the Model Unit
Set the model unit to millimeters. The default unit length in CADFEKO is metres. Since the structure that you will build is small, the model unit is set to millimetres. All dimensions entered will be in the new model unit.
1. Set the model unit to millimetres using one of the following workflows: · On the Construct tab, in the Define group, click the Model unit icon.
· On the status bar, click
.
2. On the Model Unit dialog, select Millimetres (mm). 3. Click OK to change the model unit to millimetres and to close the dialog.
Figure 56: The Model Unit dialog.
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3.4.5 Adding Variables
Define variables to create a parametric model.
A model is parametric when it is created using variable expressions. When a variable expression is modified, any items dependent on that variable are re-evaluated and automatically updated. It is the recommended construction method when creating a model, but not compulsory.
Defined variables are stored as part of the model in the .cfx file.
1. Open the Create Variable dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Add Variable icon.
· On the model tree, a right-click context menu is available on Variables. From the list, select Add Variable.
Figure 57: The model tree (Construction tab). · On the model tree, click the icon. From the drop-down list, select Add Variable.
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2. Create the following variables:
Name patch_size chamfer_d feed_pos substrate_w substrate_d substrate_h ceramic_epsR ceramic_tanD
Expression 18.8 4.3 -6.4 45 45 5 5.6 0.0041
Unit mm mm mm mm mm mm
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Figure 59: The Create Variable dialog.
Tip: · Click Add to keep the Create Variable dialog open and add more variables. · Click Create to add a variable and close the Create Variable dialog.
3. [Optional] Group the variables related to the patch. a) In the model tree, under Variables, select patch_size and chamfer_d. Tip: To select multiple objects, press and hold Ctrl while you click the items.
b) From the right-click context menu, select Group > Create. c) Select Group1 and from the right-click context menu, click Rename. d) Rename the group to Patch. 4. [Optional] Group the variables related to the substrate. a) In the model tree, select substrate_w, substrate_d and substrate_h.
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b) From the right-click context menu, select Group > Create. c) Select Group2 and from the right-click context menu, click Rename.
Tip: Press F2 to use the keyboard shortcut to rename a selected item.
d) Rename the group to Substrate.
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3.4.6 Defining a Dielectric Medium
Define a lossy frequency-independent dielectric with a relative permittivity ( ) = 5.6 and a dielectric loss tangent ( ) = 0.0041 to be used as the patch substrate.
1. Open the Create Dielectric Medium dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Media icon. From the drop-down
list, click the Dielectric icon.
· On the model tree, a right-click context menu is available on Media. From the list, click Dielectric Medium.
Two variables (ceramic_epsR and ceramic_tanD) were added to the model to define the dielectric. 2. Set the Relative permittivity ( ) to ceramic_epsR. 3. Set the Dielectric loss tangent ( ) to ceramic_tanD.
Figure 60: The Create Dielectric Medium dialog. 4. Set the Label to Ceramic. 5. Click Create to create the dielectric and to close the dialog.
Note: In the model tree, the defined dielectric is displayed under Dielectric. CADFEKO assigns a colour to each medium randomly but the colour may be changed by using the Change Display Colour right-click context menu option.
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3.4.7 Creating the Patch
Create the chamfered[10] patch using a polygon. 1. On the Construct tab, in the Create Surface group, click the
Polygon icon.
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Figure 61: The Create Polygon dialog showing the default values. Active fields are outlined in yellow.
Note: Default values are used on geometry creation dialogs to allow a preview in the 3D view. You may change the values as required.
Tip: An active field allowing point-entry is indicated by a yellow outline. Point-entry allows a variable or named points to be entered by pressing Ctrl+Shift+left click on a variable or named point in the model tree.
2. Under Corner 1, add the following coordinates: · Corner 1: U: patch_size V: patch_size N: substrate_h
10. An edge created at 45° between two adjoining right-angled edges.
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3. In the table, click on the second row to make Corner 2 active. Add the following coordinates: · Corner 2: U: -patch_size + chamfer_d V: patch_size N: substrate_h
4. Click on the third row to make Corner 3 active. Add the following coordinates: · Corner 3: U: -patch_size V: patch_size - chamfer_d N: substrate_h
5. Click Add row for Corner 4. Add the following coordinates: · Corner 4: U: -patch_size V: -patch_size N: substrate_h
6. Repeat Step 5 twice to add Corner 5 and Corner 6 using the following coordinates: · Corner 5: U: patch_size - chamfer_d V: -patch_size N: substrate_h · Corner 6: U: patch_size V: -patch_size + chamfer_d N: substrate_h
7. Set the Label to patch.
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Figure 62: The Create Polygon dialog. 8. Click Create to create the polygon and to close the dialog.
Figure 63: Top view of the chamfered patch. Note that the face is set to perfect electric conductor (PEC) by default (PEC is indicated by the colour orange).
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3.4.8 Creating the Patch Substrate
Create a finite substrate[11] by creating a cuboid. Set the region of the cuboid to the medium, ceramic. Create the cuboid.
a) On the Construct tab, in the Create Solid group, click the Cuboid icon.
b) Create the cuboid using the Base corner, width, depth, height definition method. c) Use the following dimensions:
· Base corner (C): (-22.5, -22.5, 0) · Width (W): substrate_w · Depth (D): substrate_d · Height (H): substrate_h · Label: substrate
Figure 64: The Create Cuboid dialog. d) Click Create to create the substrate and to close the dialog.
11. An alternative method is to model the substrate using an infinite planar multilayer substrate. See the Feko Example Guide for an example.
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3.4.9 Setting a Region to a Dielectric
Change the region property of the substrate to dielectric. 1. In the model tree, select substrate. 2. In the details tree, under Regions, select Region1. 3. From the right-click context menu, select Properties.
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Figure 65: The right-click context menu options available for regions. 4. On the Modify Region dialog (Properties tab), set Medium to Ceramic.
Figure 66: The Modify Region dialog. Tip: Simplify workflow by using Create new to define items when needed. 5. Click OK to modify the region property and to close the dialog. Proprietary Information of Altair Engineering
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Note: The icon in the model tree and details tree indicate items set to dielectric.
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3.4.10 Creating the Feed Pin
Create the feed pin using a single line element. 1. On the Construct tab, in the Create Curve group, click the
Line icon.
2. On the Create Line dialog, enter the start and end point for the line. · Start point: (0, feed_pos, 0) · End point: (0, feed_pos, substrate_h) · Label: feed_line
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Figure 67: The Create Line dialog. 3. Click Create to create the line and to close the dialog.
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3.4.11 Unioning the Geometry for Mesh Connectivity
Union the geometry (feed_line, patch and substrate) to create a single geometry part. A single geometry part will ensure mesh connectivity when the model is meshed.
1. In the model tree, select feed_line, patch and substrate[12].
Tip: To select multiple objects, press and hold Ctrl while you click the items.
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Figure 68: The three geometry parts in the model tree. 2. On the Construct tab, in the Modify group, click the Union icon.
Figure 69: The model tree showing Union1 (the union between feed_line, patch and substrate).
12. Alternative method is to select the items in the 3D view. Proprietary Information of Altair Engineering
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3.4.12 Setting Faces to PEC
Change the surface property of the patch to perfect electric conductor (PEC). 1. Change the face of the patch to PEC. a) In the 3D view, left-click on the patch face repeatedly until the face is highlighted in yellow.
Figure 70: Top view of patch and substrate. The yellow highlighting indicates that the patch face is selected.
b) From the right-click context menu, select Properties. c) On the Modify Face dialog (Properties tab), set the Medium to Perfect electric
conductor.
Figure 71: The Modify Face dialog. d) Click OK to change the face property and to close the dialog.
Figure 72: Top view showing the face of the patch set to PEC. 2. Change the face of the bottom substrate to PEC. Proprietary Information of Altair Engineering
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a) In the model tree, under Union1, select substrate. b) In the details tree, under Faces, go through the list of faces. For each face, click on
hide the face until only the bottom face of the substrate remains.
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Figure 73: Hidden items are greyed out when hidden in the 3D view.
c) From the right-click context menu, select Properties. d) On the Modify Face dialog (Properties tab), set Medium to Perfect electric conductor. e) Click OK to modify the face property and to close the dialog.
Figure 74: Bottom view showing the bottom substrate face set to PEC. f) In the details tree, click on any of the faces. From the right-click context menu, click
Show All to make faces visible again.
Note: The icon in the details tree indicate faces set to PEC.
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3.4.13 Ports, Sources and Loads in CADFEKO
Voltage sources and discrete loads are applied to ports and not directly to the model geometry or mesh. A port must be defined before a source or load can be added.
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Creating the Port
Define a wire port on the feed pin. A voltage source will be added to this port.
Note: A port is a mathematical representation of where energy can enter (source) or leave a model (sink). Use a port to add sources and discrete loads to a model.
1. Open the Create Wire Port dialog using one of the following workflows: · On the Source/Load tab, in the Ports group, click the Wire Port icon.
· In the details tree, a right-click context menu is available on the wire. From the list, click Create port > Wire Port.
2. Select the wire where the port is to be added. a) In the model tree, select feed_line. b) In the details tree, select the wire of feed_line.
3. Under Location on wire, select Start.
Figure 75: The Create Wire Port dialog. 4. Click Create to create the port and to close the dialog. 5. Change the label to Port1.
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Adding a Voltage Source
Add a voltage source to the port of the pin. 1. On the Source/Load tab, in the Sources on Ports group, click the 2. On the Add Voltage Source dialog, use the default settings.
Voltage Source icon.
Figure 76: The Create Voltage Source dialog.
3. Click Create to define the voltage source and to close the dialog.
Note: The Configuration tab was selected automatically when you defined the voltage source. You may also add sources, loads and set the frequency from here.
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3.4.14 Setting the Simulation Frequency
Specify the frequency range of interest. For this example continuous frequency sampling is used where Feko automatically determines the frequency sampling for optimal interpolation.
1. On the Source/Load tab, in the Settings group, click the Frequency icon.
2. On the Solution Frequency dialog, from the drop-down list, select Continuous (interpolated) range.
3. In the Start frequency (Hz) field, enter 1.27e9. 4. In the End frequency (Hz), enter 1.85e9.
Figure 77: The Solution Frequency dialog. 5. Click OK to specify the frequency and to close the dialog.
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3.4.15 Modifying the Auto-Generated Mesh
When the frequency is set or local mesh settings are applied to the geometry, the automatic mesh algorithm calculates and creates the mesh automatically while the GUI is active using default mesh settings. When required, these mesh settings may be modified.
The patch requires a finer mesh as the standard mesh size[13] and a wire segment radius needs to be specified.
1. Open the Modify Mesh Settings dialog using one of the following workflows: · On the Mesh tab, in the Meshing group, click the Modify Mesh icon.
· Press Ctrl+M to use the keyboard shortcut. 2. Set the Mesh size to Fine. 3. Set the Wire segment radius to 0.7.
Figure 78: The Modify Mesh Settings dialog. 4. Click OK to create the mesh and to close the dialog.
Figure 79: Top view of the patch and substrate showing the mesh. 5. View the effect in the 3D view of specifying a Wire segment radius.
a) Press F5 to use the keyboard shortcut to zoom to extents the 3D view. b) Enable a default cutplane. In the model tree (Construction tab), under Cutplanes, click the
icon next to XZCut[14].
13. See the Feko User Guide Appendix A-3 for more information regarding automatic mesh sizes. 14. To change the default cutplane settings, double-click on the cutplane text (for example, XZ-Cut).
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Figure 80: Note that a cutplane icon is greyed out when the cutplane is not active.
Figure 81: The cutplane shows a cross-sectional view of the patch substrate. Note the thick feedpin as specified by the Wire segment radius. c) Disable the cutplane. Click the button next to XZ-Cut again.
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3.4.16 Setting Local Mesh Sizes for Chamfered Edges
Refine the mesh locally at the chamfered edges The mesh can be refined globally but will result in an unnecessary large number of mesh elements. A more efficient approach is to only refine the mesh locally where a finer mesh is required.
Note: Local mesh refinement takes precedence over global mesh settings.
1. In the 3D view, select a chamfered edge.
Figure 82: Top view of patch and substrate. The yellow edge indicates that it is selected. 2. From the right-click context menu, select Properties. 3. On the Modify Edge dialog (Meshing tab), specify the following:
a) Select the Local mesh size check box. b) Set the Mesh size to 2.
Figure 83: The Modify Edge (Meshing tab) dialog. 4. Repeat Step 1 to Step 3 for the second chamfered edge.
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Figure 84: Top view of patch and substrate. The second chamfered edge is selected. 5. Click OK to apply the properties and to close the dialog.
Figure 85: Top view of patch and substrate showing the localised mesh refinement at the chamfered edges. Note: The icon in the details tree indicate that a local mesh setting is applied.
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3.4.17 Adding a Far Field Request
Add a far field request to the model. 1. On the Request tab, in the Solution Requests group, click the 2. On the Request Far Fields dialog, click 3D pattern.
Far Fields icon.
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Figure 86: The Request Far Fields dialog. 3. Click Create to create a far field request and to close the dialog.
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3.4.18 Deactivating Macro Recording
Deactivate the macro recording of the model, inspect the resulting Feko Lua script and use the script to recreate the model.
1. Deactivate macro recording using one of the following workflows: · On the Home tab, in the Scripting group, click the Record Macro icon. · Click the icon in the status bar.
Macro recording is deactivated. The Script Editor window is displayed containing the Feko Lua script.
Figure 87: The Script Editor window.
2. Save the Feko Lua script. a) On the Script Editor window, save the Feko Lua script by clicking on the
b) On the Save As dialog, browse to a folder and specify a file name. c) Click Save to save the Feko Lua script and to close the Save As dialog. 3. Open a new project and recreate the model using the Feko Lua script. a) On the Home tab, in the File group, click the New Project icon.
b) On the Script Editor window, click the icon to run the Feko Lua script.
icon.
The model is recreated using the Feko Lua script (see Macro Recording of Example 3).
Note: For more information regarding scripts and the Feko application programming interface (API), see the Feko Scripting and API Reference Guide.
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3.4.19 Macro Recording of Example 3
The CADFEKO macro recorded Lua script for Example 3 is given below.
application = cf.Application.getInstance()
-- NewProject project = application:NewProject()
-- SetProperties properties = application.Project.ModelAttributes:GetProperties() properties.Unit = cf.Enums.ModelUnitEnum.Millimetres application.Project.ModelAttributes:SetProperties(properties)
-- Add properties1 = cf.Variable.GetDefaultProperties() properties1.Expression = "18.8" properties1.Label = "patch_size" patch_size = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "4.3" properties1.Label = "chamfer_d" chamfer_d = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "-6.4" properties1.Label = "feed_pos" feed_pos = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "45" properties1.Label = "substrate_w" substrate_w = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "45" properties1.Label = "substrate_d" substrate_d = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "5" properties1.Label = "substrate_h" substrate_h = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "5.6" properties1.Label = "ceramic_epsR" ceramic_epsR = application.Project.Definitions.Variables:Add(properties1)
-- Add properties1.Expression = "0.0041" properties1.Label = "ceramic_tanD" ceramic_tanD = application.Project.Definitions.Variables:Add(properties1)
-- CreateGroup group1 = application.Project.Definitions.Variables:CreateGroup()
-- MoveIn group1:MoveIn({patch_size, chamfer_d})
-- Setting Label group1.Label = "Patch"
-- CreateGroup group11 = application.Project.Definitions.Variables:CreateGroup()
-- MoveIn group11:MoveIn({substrate_w, substrate_d, substrate_h})
-- Setting Label group11.Label = "Substrate"
-- AddDielectric properties2 = cf.Dielectric.GetDefaultProperties() properties2.DielectricModelling.RelativePermittivity = "ceramic_epsR"
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properties2.DielectricModelling.LossTangent = "ceramic_tanD" properties2.Label = "Ceramic" ceramic = application.Project.Definitions.Media.Dielectric:AddDielectric(properties2)
-- Setting Colour ceramic.Colour = "#aa55ff"
-- AddPolygon properties3 = cf.Polygon.GetDefaultProperties() properties3.Corners[1].U = "patch_size" properties3.Corners[1].V = "patch_size" properties3.Corners[1].N = "substrate_h" properties3.Corners[2].U = "-patch_size + chamfer_d" properties3.Corners[2].V = "patch_size" properties3.Corners[2].N = "substrate_h" properties3.Corners[3].U = "-patch_size" properties3.Corners[3].V = "patch_size - chamfer_d" properties3.Corners[3].N = "substrate_h" properties3.Corners[4] = {} properties3.Corners[4].U = "-patch_size" properties3.Corners[4].V = "-patch_size" properties3.Corners[4].N = "substrate_h" properties3.Corners[5] = {} properties3.Corners[5].U = "patch_size - chamfer_d" properties3.Corners[5].V = "-patch_size" properties3.Corners[5].N = "substrate_h" properties3.Corners[6] = {} properties3.Corners[6].U = "patch_size" properties3.Corners[6].V = " -patch_size + chamfer_d" properties3.Corners[6].N = "substrate_h" properties3.LocalWorkplane.WorkplaneDefinitionOption
= cf.Enums.LocalWorkplaneDefinitionEnum.UsePredefinedWorkplane globalXY = application.Project.Definitions.Workplanes:Item("Global XY") properties3.LocalWorkplane.ReferencedWorkplane = globalXY properties3.Label = "patch" patch = application.Project.Contents.Geometry:AddPolygon(properties3)
-- AddCuboid properties4 = cf.Cuboid.GetDefaultProperties() properties4.Origin.U = "-22.5" properties4.Origin.V = "-22.5" properties4.Width = "substrate_w" properties4.Depth = "substrate_d" properties4.Height = "substrate_h" properties4.LocalWorkplane.WorkplaneDefinitionOption
= cf.Enums.LocalWorkplaneDefinitionEnum.UsePredefinedWorkplane properties4.LocalWorkplane.ReferencedWorkplane = globalXY properties4.Label = "substrate" substrate = application.Project.Contents.Geometry:AddCuboid(properties4)
-- SetProperties properties5 = substrate.Regions:Item("Region1"):GetProperties() properties5.Medium = ceramic substrate.Regions:Item("Region1"):SetProperties(properties5)
-- AddLine properties6 = cf.Line.GetDefaultProperties() properties6.StartPoint.V = "feed_pos" properties6.EndPoint.U = "0" properties6.EndPoint.V = "feed_pos" properties6.EndPoint.N = "substrate_h" properties6.LocalWorkplane.WorkplaneDefinitionOption
= cf.Enums.LocalWorkplaneDefinitionEnum.UsePredefinedWorkplane properties6.LocalWorkplane.ReferencedWorkplane = globalXY properties6.Label = "feed_line" feed_line = application.Project.Contents.Geometry:AddLine(properties6)
-- AddUnion union1 = application.Project.Contents.Geometry:Union({patch, substrate, feed_line})
-- SetProperties properties7 = union1.Faces:Item("Face8"):GetProperties() perfectElectricConductor = application.Project.Definitions.Media.PerfectElectricConductor properties7.Medium = perfectElectricConductor union1.Faces:Item("Face8"):SetProperties(properties7)
-- ToggleVisibility
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substrate.Faces:Item("Face2"):ToggleVisibility()
-- ToggleVisibility substrate.Faces:Item("Face2"):ToggleVisibility()
-- SetProperties properties8 = union1.Faces:Item("Face6"):GetProperties() properties8.Medium = perfectElectricConductor union1.Faces:Item("Face6"):SetProperties(properties8)
-- AddWirePort properties9 = cf.WirePort.GetDefaultProperties() edge19 = feed_line.Edges:Item("Edge19") properties9.Wire = edge19 properties9.Label = "Port1" port1 = application.Project.Contents.Ports:AddWirePort(properties9)
-- AddVoltageSource properties10 = cf.VoltageSource.GetDefaultProperties() properties10.Terminal = port1 properties10.Label = "VoltageSource1" voltageSource1 =
application.Project.Contents.SolutionConfigurations.GlobalSources:AddVoltageSource(properties10)
-- SetProperties properties11 = application.Project.Contents.SolutionConfigurations.GlobalFrequency:GetProperties() properties11.Start = "1.27e9" properties11.End = "1.85e9" properties11.RangeType = cf.Enums.FrequencyRangeTypeEnum.Continuous application.Project.Contents.SolutionConfigurations.GlobalFrequency:SetProperties(properties11)
-- SetProperties properties12 = application.Project.Mesher.Settings:GetProperties() properties12.MeshSizeOption = cf.Enums.MeshSizeOptionEnum.Fine properties12.WireRadius = "07" properties12.Advanced.GrowthRate = 30 properties12.Advanced.RefinementFactor = 80 properties12.Advanced.MinElementSize = 80 application.Project.Mesher.Settings:SetProperties(properties12)
-- ToggleVisibility application.Project.Contents.Cutplanes:Item("XZ-Cut"):ToggleVisibility()
-- ToggleVisibility application.Project.Contents.Cutplanes:Item("XZ-Cut"):ToggleVisibility()
-- SetProperties properties13 = union1.Edges:Item("Edge6"):GetProperties() properties13.LocalMeshSizeEnabled = true properties13.LocalMeshSize = "2" union1.Edges:Item("Edge6"):SetProperties(properties13)
-- SetProperties properties14 = union1.Edges:Item("Edge3"):GetProperties() properties14.LocalMeshSizeEnabled = true properties14.LocalMeshSize = "2" union1.Edges:Item("Edge3"):SetProperties(properties14)
-- Add properties15 = cf.FarField.GetDefaultProperties() properties15.Theta.End = "180.0" properties15.Theta.Increment = "5.0" properties15.Phi.End = "360.0" properties15.Phi.Increment = "5.0" properties15.Label = "FarField1" properties15.LocalWorkplane.WorkplaneDefinitionOption
= cf.Enums.LocalWorkplaneDefinitionEnum.UsePredefinedWorkplane properties15.LocalWorkplane.ReferencedWorkplane = globalXY farField1 =
application.Project.Contents.SolutionConfigurations:Item("StandardConfiguration1").FarFields:Add(properties15)
-- SaveAs application:SaveAs("C:/Users/eh/Desktop/Example2.CADFEKO")
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3.4.20 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Patch.cfx. 3. Click Save to close the dialog.
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3.5 Launching the Solver
Launch the Solver to calculate the results. No requests were added to this model since impedance and current information are calculated automatically for all voltage and current sources in the model.
1. Launch the Solver using one of the following workflows: · On the Solve/Run tab, in the Run/Launch group, click the Feko Solver icon.
· On the application launcher toolbar, click the Feko Solver icon in the
group.
· Press Alt+4 to use the keyboard shortcut. If the model contains unsaved changes, the Save Model dialog is displayed.
2. Click Yes to save the model and to close the Save Model dialog. The Feko Solver is launched and the Executing runfeko dialog is displayed. The dialog gives step-bystep feedback as the simulation progresses.
3. Click Details to expand the Executing runfeko to view the step-by-step feedback.
Figure 88: The Executing runfeko dialog.
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3.6 Viewing the Results in POSTFEKO
Display the model as well as the results using the post-processor component, POSTFEKO.
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3.6.1 Launching POSTFEKO
Open POSTFEKO from within CADFEKO. Use one of the following workflows to launch POSTFEKO:
· On the Solve/Run tab, in the Run/Launch group, click the
POSTFEKO icon.
· On the application launcher toolbar, click the POSTFEKO icon in the
group.
· Press Alt+3 to use the keyboard shortcut.
POSTFEKO opens by default with a single 3D view containing the model geometry.
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3.6.2 Viewing the Input Reflection Coefficient
View the input reflection coefficient on a Cartesian graph in dB. 1. On the Home tab, in the Create new display group, click the
Cartesian icon.
2. On the Home tab, in the Add results group, click the Source data icon. From the drop-down list, select VoltageSource1.
3. View the input reflection coefficient in dB versus frequency. a) On the result palette, in the Traces panel, select VoltageSource1. b) On the Quantity panel, confirm that Reflection coefficient is selected (default option). c) On the Quantity panel, select the dB check box.
Figure 89: The result palette containing the Traces, Source, Slice and Quantity panels (listed from top to bottom).
4. Change the legend position to bottom-right. a) On the Display tab, in the Display group, click the list select Overlay bottom right.
5. Remove the graph footer. a) On the Display tab, in the Display group, click the
Position icon. From the drop-down Chart text icon.
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b) In the Graph footer field, clear the Auto check box and delete the text. c) Click OK to apply the text changes and to close the dialog.
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Figure 90: The input reflection coefficient in dB versus frequency.
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3.6.3 Viewing the Circular Components of the Far Field
1. On the Home tab, in the Create new display group, click the Cartesian icon.
2. On the Home tab, in the Add results group, click the Far Field Source icon. From the dropdown list, select FarField1.
3. Make a copy of the trace, FarField1. a) On the result palette, in the Traces panel, select FarField1. b) Duplicate the trace, FarField1, using one of the following workflows: · On the Cartesian context tab, on the Trace tab, in the Manage group, click the Duplicate trace icon.
· On the result palette, a right-click context menu is available on the trace. From the dropdown list, select Duplicate trace.
· Press Ctrl+K to use the keyboard shortcut. A trace with label FarField1_1 is created. 4. Rename the trace, FarField1_1.
a) On the result palette, in the Traces panel, select FarField1_1. b) Press F2 to use the keyboard shortcut and rename the trace to FarField2. 5. View the left-hand circular component of the far field in dB versus frequency. a) In the Traces panel, select FarField1. b) On the result palette, in the Quantity panel, click LHC. c) On the result palette, in the Quantity panel, select the dB check box. 6. View the right-hand circular component of the far field in dB versus frequency. a) In the Traces panel, select the duplicate trace, FarField2. b) On the result palette, in the Quantity panel, click RHC. c) On the result palette, in the Quantity panel, select the dB check box. 7. [Optional] Repeat Step 4 and Step 5 to change the legend position and remove the graph footer.
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Figure 91: The left-hand circular and right-hand circular components of the far field.
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3.7 Final Remarks
This example showed the construction, configuration and solution of a left-handed circular polarised GPS patch antenna on a finite substrate. The input reflection coefficient and circular components of the far field were calculated and displayed.
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GPS Patch on Quadcopter
4 GPS Patch on Quadcopter
The example considers the antenna placement of a GPS patch antenna on a quadcopter.
This chapter covers the following: · 4.1 Example Overview (p. 119) · 4.2 Topics Discussed in Example (p. 120) · 4.3 Example Prerequisites (p. 121) · 4.4 Creating the Model in CADFEKO (p. 122) · 4.5 Launching the Solver (p. 134) · 4.6 Viewing the Results in POSTFEKO (p. 135) · 4.7 Final Remarks (p. 137)
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4.1 Example Overview
Calculate the input reflection coefficient and circular components of a left-handed circular polarised GPS patch antenna on a finite substrate close to 1.57 GHz placed on a quadcopter. Compare the results with that of Example 3.
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4.2 Topics Discussed in Example
The topics discussed in this example are: · CADFEKO Specify the model unit. Add a component from the component library. Import a model from a .cfx file. Create a workplane and perform transformations on the workplane (rotate). Use the Align tool for antenna placement. Run the Solver. Show/hide the simulation mesh in the 3D view. Show/hide a part in the 3D view. · POSTFEKO View the Lua script to set up the graphs (similar to Example 2) for the following: View the input reflection coefficient on a Cartesian graph. View the left-hand and right-hand circular components of the far field on a Cartesian graph. View an example of a Lua script to configure graphs.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[15]: GS 4: GPS Patch on a Drone
15. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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4.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 40 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[16] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
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4.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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4.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 92: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
4.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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4.4.3 Setting the Model Unit
Set the model unit to millimeters. The default unit length in CADFEKO is metres. Since the structure that you will build is small, the model unit is set to millimetres. All dimensions entered will be in the new model unit.
1. Set the model unit to millimetres using one of the following workflows: · On the Construct tab, in the Define group, click the Model unit icon.
· On the status bar, click
.
2. On the Model Unit dialog, select Millimetres (mm). 3. Click OK to change the model unit to millimetres and to close the dialog.
Figure 93: The Model Unit dialog.
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4.4.4 Adding a Quadcopter from the Component Library
Select a simplified quadcopter model from the Component library and add it to the project. 1. On the Home tab, in the File group, click the Component Library icon. 2. On the Component Library dialog, in the Filter field, enter the text quadcopter.
Figure 94: The Component Library dialog. 3. From the filtered results, click Quadcopter - Simple. 4. Click Add to model to add the quadcopter and to close the dialog. 5. On the Align dialog, under Destination workplane, in the Origin field, for the Z field, enter a
value of -100.
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Figure 95: The Align dialog. Note: The offset separates the patch from the quadcopter on import. 6. Click OK to place the quadcopter and to close the dialog.
Figure 96: The simple quadcopter model from the component library. Proprietary Information of Altair Engineering
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4.4.5 Importing the GPS Patch
Import the GPS patch model (.cfx file) created in Example 3. 1. On the Home tab, in the File group, click the Import icon. From the drop-down list select the CADFEKO Model (*.cfx) icon. 2. On the Import CADFEKO Model dialog, browse to the location of where you saved Example 3[17] and click OK.
Figure 97: The Import CADFEKO Model dialog. The patch is located above the quadcopter. The next step is to align the GPS patch with the quadcopter.
Figure 98: The imported GPS patch model above the quadcopter. 17. Alternatively, open GS 3: GPS Patch Antenna in the application macro library.
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4.4.6 Defining a Workplane
Define a workplane to assist with aligning the patch on the quadcopter. 1. Hide the patch antenna in the 3D view to focus on the quadcopter. a) In the model tree, click the icon next to Union1.
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Figure 99: Union1 is greyed out to indicate that the part is hidden in the 3D view.
2. Hide the simulation mesh[18] to focus on the geometry using one of the following workflows: · On the status bar, click the Overlay icon.
· On the 3D View context tab, on the Display Options tab, in the Display Mode group, click the Overlay icon.
3. Define a workplane. a) On the Construct tab, in the Define group, click the
Add Workplane icon.
Figure 100: The Create Workplane dialog. 18. The simulation mesh refers to the final mesh used by the Solver. CAD always has to be meshed.
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b) Press Ctrl+Shift while moving the mouse cursor over the top face centre of the quadcopter.
Note: The circles with a black outline indicate special snapping points. The red outline indicates the position of the mouse cursor. Use snapping points to snap the workplane to an object. Although only special snapping points are indicated, you can snap to any point in the 3D view.
Figure 101: Special snapping points are indicated by circles with a black outline. The red outline indicates the position of the mouse cursor.
c) Press Ctrl+Shift+left click to snap the workplane to the top face centre of the quadcopter. d) Click Create to create Workplane1 and to close the dialog.
Figure 102: Workplane1 has snapped to the top centre of the quadcopter. 4. Align Workplane1 with the top of the quadcopter.
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a) In the model tree, select Workplane1. b) From the right-click context menu, click Transforms > Rotate. c) On the Rotate dialog, under Rotation angle, in the Angle [degrees] field, specify a value
of 45°.
Figure 103: The Rotate dialog. d) Click OK to rotate Workplane1 and to close the dialog.
Figure 104: Workplane1 is "aligned" to the top centre of the quadcopter. 5. Repeat Step 1 to show the patch again. Proprietary Information of Altair Engineering
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4.4.7 Aligning the Patch and Quadcopter
Align the patch to the quadcopter. 1. In the model tree, select Quadcopter_simple. 2. Align the GPS patch antenna on the quadcopter. a) On the Transform tab, in the Transform group, click the
Align icon.
b) On the Align dialog, under Source workplane, select Predefined workplane. From the drop-down list, select Workplane1.
Tip: If Workplane1 is unavailable in the drop-down list, repeat Step 1.
c) Under Destination workplane, select Custom workplane.
· Click the X, Y or Z field to make it active. · Press Ctrl+Shift and hover with the mouse over the top face of the patch and click when
the workplane snaps to the center point.
Figure 105: The Align dialog. d) Click OK to align the quadcopter to the patch and to close the dialog.
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Figure 106: The GPS patch antenna placed on the quadcopter.
3. Union the GPS patch antenna and the quadcopter using one of the following workflows: · On the Construct tab, in the Modify group, click the Union icon. · Press U to use the keyboard shortcut.
Note: The union operation is used to define connectivity between parts.
Parts that touch, but are not unioned, are not considered to be physically connected and will result in an incorrect mesh.
4. Show the simulation mesh again. a) On the status bar, click the
Overlay icon.
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4.4.8 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Patch_on_Drone.cfx. 3. Click Save to close the dialog.
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4.5 Launching the Solver
Launch the Solver to calculate the results. No requests were added to this model since impedance and current information are calculated automatically for all voltage and current sources in the model.
1. Launch the Solver using one of the following workflows: · On the Solve/Run tab, in the Run/Launch group, click the Feko Solver icon.
· On the application launcher toolbar, click the Feko Solver icon in the
group.
· Press Alt+4 to use the keyboard shortcut. If the model contains unsaved changes, the Save Model dialog is displayed.
2. Click Yes to save the model and to close the Save Model dialog. The Feko Solver is launched and the Executing runfeko dialog is displayed. The dialog gives step-bystep feedback as the simulation progresses.
3. Click Details to expand the Executing runfeko to view the step-by-step feedback.
Figure 107: The Executing runfeko dialog.
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4.6 Viewing the Results in POSTFEKO
Display the model as well as the results using the post-processor component, POSTFEKO.
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4.6.1 Using a Lua Script to Configure Graphs
View the Lua script to set up the graphs for the input reflection coefficient and circular components of the far field.
The step-by-step instructions to create this script is beyond the scope of the Feko Getting Started Guide, but it is recommended to view the script and to compare it with setting up Graph 1 and Graph 2 from Example 3.
app = pf.GetApplication() -- Graph 1 graph1 = app.CartesianGraphs:Add() excitationTrace = graph1.Traces:Add(app.Models[1].Configurations[1].Excitations[1]) excitationTrace.Quantity.ValuesScaledToDB = true graph2.Footer.Text = "" graph2.Legend.Position = pf.Enums.GraphLegendPositionEnum.OverlayBottomRight
-- Graph 2 graph2 = app.CartesianGraphs:Add() farFieldTraceLHC = graph2.Traces:Add(app.Models[1].Configurations[1].FarFields[1]) farFieldTraceLHC.Quantity.Type = pf.Enums.FarFieldQuantityTypeEnum.Gain farFieldTraceLHC.Quantity.Component = pf.Enums.FarFieldQuantityComponentEnum.LHC farFieldTraceLHC.Quantity.ValuesScaledToDB = true
farFieldTraceRHC = farFieldTraceLHC:Duplicate() farFieldTraceRHC.Quantity.Type = pf.Enums.FarFieldQuantityTypeEnum.Gain farFieldTraceRHC.Quantity.Component = pf.Enums.FarFieldQuantityComponentEnum.RHC farFieldTraceRHC.Label = "FarField2"
farFieldTraceRHC.Quantity.ValuesScaledToDB = true graph2.Footer.Text = "" graph2.Legend.Position = pf.Enums.GraphLegendPositionEnum.OverlayBottomRight
Note: For more information regarding scripts and the Feko application programming interface (API), see the Feko Scripting and API Reference Guide.
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4.7 Final Remarks
This examples showed how to place a GPS patch antenna on a quadcopter that was obtained from the component library. The input reflection coefficient and circular components of the far field were calculated and displayed.
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EMC Coupling
5
5 EMC Coupling
The example considers the coupling between a typical monopole antenna and a loaded transmission line above a ground plane.
This chapter covers the following:
· 5.1 Example Overview (p. 139) · 5.2 Topics Discussed in Example (p. 140) · 5.3 Example Prerequisites (p. 141) · 5.4 Creating the Model in CADFEKO (p. 142) · 5.5 Launching the Solver (p. 159) · 5.6 Viewing the Results in POSTFEKO (p. 160) · 5.7 Final Remarks (p. 165)
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5.1 Example Overview
Consider the coupling between a monopole antenna and a loaded transmission line above a ground plane.
Create the monopole antenna using a line and the loaded transmission line using a polyline. The ground plane is modelled using an infinite ground plane.
Figure 108: The monopole antenna and the loaded transmission line above an infinite ground plane.
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5.2 Topics Discussed in Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· CADFEKO Create a monopole using a line. Specify the local wire radius for the monopole. Create the transmission line using a polyline. Define a ground plane using an infinite ground plane. Add a port and voltage source to the monopole. Specify the radiated power of the model. Add a port and complex load to the transmission line. Set the solution frequency. Use adaptive frequency sampling to obtain continuous data. Mesh the model. Run CEM validate to ensure the model is electromagnetically validated. Run the Solver.
· POSTFEKO View the simulated input impedance and currents on a graph. Change the line colour, marker style, marker colour of a trace on the graph. Add shapes (line, arrow, rectangle or circle) to highlight certain areas on the graph.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[19]: GS 5: EMC Coupling
19. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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5.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 30 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[20] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
20. See the Troubleshooting section in the Appendix of the Feko User Guide for more details. Proprietary Information of Altair Engineering
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5.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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5.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 109: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
5.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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5.4.3 Creating a Monopole
Create a monopole antenna as a single line element with a local wire radius. Zoom to extents and hide the main axes to view the full-length monopole in the 3D view. Create the monopole antenna. The length of the monopole is 12 m along the Z axis.
1. Create a line. a) On the Construct tab, in the Create Curve group, click the Line icon.
b) On the Create Line dialog, enter the start point and end point for the line. · Start point: (0, 0, 0) · End point: (0, 0, 12)
Note: Default values are used on geometry creation dialogs to allow a preview in the 3D view. You may change the values as required.
Figure 110: The Create Line dialog.
2. Set the label to Monopole. 3. Click Create to create the line and close the dialog. To view the full-length monopole in the 3D window, zoom the monopole to the window extent. 4. Zoom to extents of the 3D view using one of the following workflows:
· On the View tab, in the Zoom group, click the Zoom to Extents icon. · Press F5 to use the keyboard shortcut. Disable the main axes to view the monopole without the Z axis obstructing it.
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5. On the 3D View context tab, on the Display Options tab, in the Axes group, click the Axes icon.
6. Repeat Step 5 to enable the main axes display.
Main
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5.4.4 Creating a Transmission Line
Create a transmission line using a polyline curve with four corners. The length of the polyline is 12 m along the Y axis, placed 50 mm above ground.
1. On the Construct tab, in the Create Curve group, click the Polyline icon.
Figure 111: The Create Polyline dialog.
2. Under Corner 1, add the following coordinates: · Corner 1: (0, 2 0)
3. In the table, click on the second row to make Corner 2 active. Under Corner 2, add the following coordinates: · Corner 2: (0, 2, 0.05)
4. Click on Add row. Under Corner 3, add the following coordinates: · Corner 3: (0, 14, 0.05)
5. Click on Add row. Under Corner 4, add the following coordinates: · Corner 4: (0, 14, 0)
6. Set the label to Transmission_line. 7. Click Create to create the polyline and to close the dialog. 8. Zoom to extents of the 3D view using one of the following workflows:
· On the View tab, in the Zoom group, click the Zoom to Extents icon. · Press F5 to use the keyboard shortcut.
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5.4.5 Defining an Infinite Ground Plane
Define a perfectly conducting (PEC) infinite ground plane. An infinite ground plane is an efficient method to model a large ground plane compared to a discretised, finite sized ground plane. Define the infinite ground plane.
a) On the Construct tab, in the Structures group, click the Planes/Arrays icon. From the
drop-down list, select Plane / Ground.
b) On the Plane / Ground dialog, from the Definition method drop-down list, select Perfect electric (PEC) ground plane at Z=0.
Figure 112: The Plane / Ground dialog. c) Click OK to create the infinite plane and to close the dialog.
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5.4.6 Ports, Sources and Loads in CADFEKO
Voltage sources and discrete loads are applied to ports and not directly to the model geometry or mesh. A port must be defined before a source or load can be added.
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Adding a Wire Port to the Monopole
Define a wire port on the monopole. A voltage source will be added to this port. 1. Select the monopole using one of the following workflows: · Click on the monopole in the 3D view. · In the model tree, select Monopole. In the details tree, select Edge1.
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Figure 113: Edge1 in the details tree is the wire element associated with Line1 in the model tree.
2. Define the wire port on the selected wire (monopole) using one of the following workflows: · On the Source/Load tab, in the Ports group, click the Wire Port icon. · On the details tree, a right-click context menu is available on the edge. Click Create Port > Wire Port.
Figure 114: The right-click context menu options for an edge in the details tree. 3. Use the default port settings.
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Figure 115: The Create Wire Port dialog. 4. Click Create to create the port and close the dialog.
Figure 116: Front view of the monopole and its wire port and the transmission line. The port is indicated by a silver sphere.
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Adding a Wire Port to the Transmission Line
Define a wire port for the transmission line. 1. Select the short, vertical wire in the 3D view located farthest away from the monopole. The wire element associated with the selected wire is highlighted in the details tree. 2. On the details tree, a right-click context menu is available on the edge. Click Create Port > Wire Port (see Figure 2). 3. View the port preview in the 3D view to ensure the correct edge is selected. 4. Use the default settings for the port.
Figure 117: The Create Wire Port dialog. 5. Create Create to create the port and close the dialog.
Figure 118: Front view of the monopole and transmission line together with their wire ports. The ports are indicated by silver spheres.
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Adding a Voltage Source
Add a voltage source to the port of the monopole. 1. On the Source/Load tab, in the Sources on Ports group, click the
Voltage Source icon.
The radiated power must be 1 Watt for this example. Since the input impedance for the monopole is not known, the voltage can not be changed to scale the radiated power.
2. Ensure WirePort1 is selected in the drop-down list and use the default voltage settings.
3. Click Create to define the voltage source and to close the dialog.
Figure 119: Front view of the monopole and transmission line together with their wire ports. The wire port with a voltage source applied to it, is indicated by a red sphere.
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Adding a Complex Load to a Port
Add a resistive load to the port of the transmission line. 1. On the Source/Load tab, in the Loads/Networks group, click the 2. Specify the port for the load as WirePort2. 3. Set the Real part of the complex impedance to 1000.
Add Load icon.
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4. Click Create to create the load and close the dialog.
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5.4.7 Setting the Radiated Power Level
Specify the power settings to scale the radiated power. 1. On the Source/Load tab, in the Settings group, click the
Power icon.
The radiated power should be 1 Watt. Power losses as a result of source mismatch are deducted before the 1 Watt is calculated.
2. Click Total source power (no mismatch). 3. Enter a source power of 1 Watt.
4. Click OK to specify the source power and to close the dialog.
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5.4.8 Setting the Simulation Frequency
Specify the frequency range of interest. For this example continuous frequency sampling is used where Feko determines the frequency sampling for optimal interpolation automatically.
1. On the Source/Load tab, in the Settings group, click the Frequency icon.
2. On the Solution Frequency dialog, select Continuous (interpolated) range from the dropdown list.
Specify the frequency range between 1 MHz and 30 MHz. 3. Enter the start frequency and end frequency. · Start frequency (Hz): 1e6 · End frequency (Hz): 30e6
Figure 120: The Solution Frequency dialog. 4. Click OK to specify the frequency and to close the dialog.
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5.4.9 Modifying the Auto-Generated Mesh
When the frequency is set or local mesh settings are applied to the geometry, the automatic mesh algorithm calculates and creates the mesh automatically while the GUI is active using default mesh settings. When required, these mesh settings may be modified.
Specify the global wire segment radius to be used in the model. 1. Open the Modify Mesh Settings dialog using one of the following workflows: · On the Mesh tab, in the Meshing group, click the Modify Mesh icon.
· Press Ctrl+M to use the keyboard shortcut. 2. On the Modify Mesh Settings dialog, set the Wire segment radius to 0.004.
Figure 121: The Modify Mesh Settings dialog. 3. Click OK to create the mesh and to close the dialog.
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5.4.10 Setting a Local Wire Radius for the Monopole
Specify a local wire radius for the monopole. The monopole and transmission line are each assigned a different wire radius. Due to the differences in the wire radii, we specify a local wire radius for the monopole.
Note: Local mesh refinement takes precedence over global mesh settings.
1. In the model tree (Construction tab), select Monopole. In the details tree, select Edge1. 2. From the right-click context menu, select Properties. 3. On the Modify Edge dialog (Properties tab), specify the following:
a) Select the Local wire radius check box. b) Set the Radius to 0.015.
Figure 122: The Modify Edge dialog. 4. Click OK to apply the properties and to close the dialog.
Note: The icon in the details tree indicate that a local wire radius is applied.
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5.4.11 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Coupling.cfx. 3. Click Save to close the dialog.
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5.5 Launching the Solver
Launch the Solver to calculate the results. No requests were added to this model since impedance and current information are calculated automatically for all voltage and current sources in the model.
1. Launch the Solver using one of the following workflows: · On the Solve/Run tab, in the Run/Launch group, click the Feko Solver icon.
· On the application launcher toolbar, click the Feko Solver icon in the
group.
· Press Alt+4 to use the keyboard shortcut. If the model contains unsaved changes, the Save Model dialog is displayed.
2. Click Yes to save the model and to close the Save Model dialog. The Feko Solver is launched and the Executing runfeko dialog is displayed. The dialog gives step-bystep feedback as the simulation progresses.
3. Click Details to expand the Executing runfeko to view the step-by-step feedback.
Figure 123: The Executing runfeko dialog.
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5.6 Viewing the Results in POSTFEKO
Display the model as well as the results using the post-processor component, POSTFEKO.
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5.6.1 Launching POSTFEKO
Open POSTFEKO from within CADFEKO. Use one of the following workflows to launch POSTFEKO:
· On the Solve/Run tab, in the Run/Launch group, click the
POSTFEKO icon.
· On the application launcher toolbar, click the POSTFEKO icon in the
group.
· Press Alt+3 to use the keyboard shortcut.
POSTFEKO opens by default with a single 3D view containing the model geometry.
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Viewing the Load Current
View the load current of the transmission line on a Cartesian graph. 1. Create a new Cartesian graph. a) On the Home tab, in the Create new display group, click the
Cartesian icon.
2. Add the load current to the Cartesian graph. a) On the Home tab, in the Add results group, click the Loads/Networks icon. From the drop-down list, select Load1.
3. View the load current (in dB) versus frequency. a) On the result palette, on the Traces panel, select Load1. b) On the Quantity panel, from the drop-down list select Current. c) On the Quantity panel, select the dB check box.
4. Change the legend position to top-right. a) On the Display tab, in the Display group, click the Position icon. From the drop-down list select Overlay top right.
5. Remove the graph footer. a) On the Display tab, in the Display group, click the Chart text icon.
b) In the Graph footer field, clear the Auto check box and delete the text. c) Click OK to apply the text changes and to close the dialog.
Figure 124: The load current in dB versus frequency. Proprietary Information of Altair Engineering
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Viewing the Input Impedance
View the source input impedance (real part and imaginary part) of the transmission line on a Cartesian graph.
1. Create a new Cartesian graph. a) On the Home tab, in the Create new display group, click the Cartesian icon.
2. Add the source input impedance to the Cartesian graph. a) On the Home tab, in the Add results group, click the
Source data icon.
3. View the real part of the impedance. a) On the result palette, in the Traces panel, select VoltageSource1. b) On the Quantity panel, from the drop-down list select Impedance. c) On the Quantity panel, click Real.
4. Duplicate the VoltageSource1 trace using one of the following workflows: · On the Cartesian context tab, on the Trace tab, in the Manage group, click the Duplicate trace icon.
· On the result palette, a right-click context menu is available on the trace. From the dropdown list, select Duplicate trace.
· Press Ctrl+K to use the keyboard shortcut. 5. View the imaginary part of the impedance.
a) On the result palette, in the Traces panel, select Vo1tageSource1_1. b) On the Quantity panel, click Imaginary. 6. [Optional] Repeat Step 4 and Step 5 to change the legend position and remove the graph footer.
Figure 125: The input impedance (real and imaginary) versus frequency. Proprietary Information of Altair Engineering
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Formatting the Graph
Format the line colour, marker colour and marker style of a trace. Add a line, arrow (single or double), rectangle or circle to the graph to highlight certain aspects of the graph.
1. Select a trace to format. a) On the result palette, in the traces panel, select VoltageSource1_1.
2. Change the line colour to red. a) On the Format tab, in the Line group, click the Line colour icon. From the drop-down list, select the colour red.
3. Change the marker style to a triangle. a) On the Format tab, in the Marker group, click the Marker style icon. From the dropdown list select the triangle.
4. Change the marker colour to match the colour of the trace. a) On the Format tab, in the Marker group, click the Marker colour icon. From the dropdown list select the colour red.
5. [Optional] Repeat Step 4 and Step 5 to change the legend position and remove the graph footer.
Figure 126: An example of a formatted graph. 6. [Optional] Add a line, arrow, double arrow, rectangle or circle to the graph to highlight an aspect
on the graph. a) On the Format tab, in the Drawing group, click the Shapes icon. Select the required item from the drop-down list.
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5.7 Final Remarks
This example showed the construction, configuration and solution of an EMC coupling scenario. The model consists of a monopole antenna and transmission line on an infinite PEC ground plane. Coupling of current into the transmission line is viewed from 1 MHz to 30 MHz.
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Waveguide Power Divider
6
6 Waveguide Power Divider
The example considers the transmission and reflection coefficients of a waveguide power divider.
This chapter covers the following:
· 6.1 Example Overview (p. 167) · 6.2 Topics Discussed in Example (p. 168) · 6.3 Example Prerequisites (p. 169) · 6.4 Creating the Model in CADFEKO (p. 170) · 6.5 Launching the Solver (p. 190) · 6.6 Launching POSTFEKO (p. 191) · 6.7 Final Remarks (p. 195)
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6.1 Example Overview
Calculate the transmission and reflection coefficients of a waveguide power divider.
Create the power divider to split equally the power between the two output ports while minimising any power reflected back to the source port. The power is split by placing a metal pin at the junction between the three waveguide sections. The model utilises symmetry to reduce memory requirements and calculation speed.
Figure 127: The waveguide power divider and instantaneous near field.
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6.2 Topics Discussed in Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· CADFEKO Create the pin using a cylinder. Create the waveguide sections using cuboids. Define waveguide ports on each end of the waveguide. Add a waveguide source. Set the solution frequency. Specify local (fine) meshing for the waveguide ports. Specify symmetry to save computational resources. Specify near fields on a plane inside the waveguide. Mesh the model. Run CEM validate to ensure the model is electromagnetically validated. Run the Solver.
· POSTFEKO View the simulated input reflection coefficient on a graph. View the instantaneous near field inside the waveguide. View an animation of the near fields.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[21]: GS 6: Waveguide Power Divider
21. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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6.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 30 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[22] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
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6.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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6.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 128: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
6.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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6.4.3 Setting the Model Unit
Set the model unit to millimeters. The default unit length in CADFEKO is metres. Since the structure that you will build is small, the model unit is set to millimetres. All dimensions entered will be in the new model unit.
1. Set the model unit to millimetres using one of the following workflows: · On the Construct tab, in the Define group, click the Model unit icon.
· On the status bar, click
.
2. On the Model Unit dialog, select Millimetres (mm). 3. Click OK to change the model unit to millimetres and to close the dialog.
Figure 129: The Model Unit dialog.
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6.4.4 Adding Variables
Define variables to create a parametric model.
A model is parametric when it is created using variable expressions. When a variable expression is modified, any items dependent on that variable are re-evaluated and automatically updated. It is the recommended construction method when creating a model, but not compulsory.
Defined variables are stored as part of the model in the .cfx file.
1. Open the Create Variable dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Add Variable icon.
· On the model tree, a right-click context menu is available on Variables. From the list, select Add Variable.
Figure 130: The model tree (Construction tab). · On the model tree, click the icon. From the drop-down list, select Add Variable.
Figure 131: The drop-down list available in the model tree. · Press # to use the keyboard shortcut. Proprietary Information of Altair Engineering
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2. Create the following variables: a) Optional: Add the variable comments.
Name freq lambda pin_r wg_h wg_w
Expression 9e9 c0/freq*1000 1 10 20
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Comment The operating frequency. Free space wavelength. Pin radius. Waveguide height. Waveguide width.
Tip: · Click Add to keep the Create Variable dialog open and add more variables. · Click Create to add a variable and close the Create Variable dialog.
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6.4.5 Creating the Power Dividing Pin
Create the power dividing pin using a cylinder. 1. Create a cylinder located at the origin along the Z axis. a) On the Construct tab, in the Create Solid group, click the
Cylinder icon.
b) Create a cylinder using the Base centre, radius, height definition method. c) Use the following dimensions:
· Radius (R): pin_r · Height (H): wg_h
Note: Default values are used on geometry creation dialogs to allow a preview in the 3D view. You may change the values as required.
a) Click Create to create the cylinder and to close the dialog.
Figure 132: The Create Cylinder dialog. 2. Zoom to extents of the 3D view using one of the following workflows:
· On the View tab, in the Zoom group, click the Zoom to Extents icon. · Press F5 to use the keyboard shortcut.
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6.4.6 Creating the Waveguide Sections
Create the waveguide sections using two cuboids. 1. Create the first waveguide section. a) On the Construct tab, in the Create Solid group, click the
Cuboid icon.
b) Create the cuboid using the Base centre, width, depth, height definition method. c) Use the following dimensions:
· Base centre (C): (0, 0, 0) · Width (W): wg_w · Depth (D): 2*wg_w · Height (H): wg_h · Label: Cuboid1
Figure 133: The Create Cuboid dialog. d) Click OK to create the waveguide section and to close the dialog. 2. Create the second waveguide section. a) On the Construct tab, in the Create Solid group, click the Cuboid icon. b) Create the cuboid using the Base corner, width, depth, height definition method. c) Use the following dimensions:
· Base corner (C): (wg_w/2, -wg_w/2, 0)
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· Width (W): wg_w · Depth (D): wg_w · Height (H): wg_h · Label: Cuboid2
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Figure 134: The Create Cuboid dialog. d) Click OK to create the waveguide section and to close the dialog.
Figure 135: The two waveguide sections and power dividing pin. Proprietary Information of Altair Engineering
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6.4.7 Unioning the Geometry for Mesh Connectivity
Union the geometry (Cuboid1 and Cuboid2) to create a single geometry part. A single geometry part will ensure mesh connectivity when the model is meshed.
1. In the model tree, select Cuboid1 and Cuboid2[23].
Tip: To select multiple objects, press and hold Ctrl while you click the items.
Figure 136: Cuboid1 and Cuboid2 selected in the model tree. 2. On the Construct tab, in the Modify group, click the Union icon.
Figure 137: The model tree showing Union1 (the union between Cuboid1 and Cuboid2).
23. Alternative method is to select the items in the 3D view. Proprietary Information of Altair Engineering
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6.4.8 Removing Redundant Faces
Use the simplify tool to remove redundant faces. 1. In the model tree, select Union1. 2. On the Transform tab, in the Simplify group, click the 3. Use the default settings on the Simplify dialog.
Simplify icon.
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Figure 138: The Simplify dialog. 4. Click Create to simplify Union1 and to close the dialog. The redundant face at the junction between the two cuboids is removed.
Figure 139: The waveguide section after the redundant faces were removed.
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6.4.9 Changing the Waveguide to a Shell (Hollow) Part
Change the solid waveguide part to a shell (hollow) part with metal walls. 1. In the model tree, select Union1. 2. In the details tree, under Regions, select Region1. 3. From the right-click context menu, select Properties.
Figure 140: The right-click context menu options available for regions. 4. On the Modify Region dialog (Properties tab), set Medium to Free space.
Figure 141: The Modify Region dialog. 5. Click OK to modify the region properties and to close the dialog.
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6.4.10 Unioning the Waveguide and Power Dividing Pin
Create a single geometry part from the waveguide and power divider pin to ensure mesh connectivity when the model is meshed.
1. In the model tree, select Cylinder1 and Union1[24].
Tip: To select multiple objects, press and hold Ctrl while you click the items.
2. On the Construct tab, in the Modify group, click the Union icon.
Figure 142: Select Cylinder1 and Union1 in the model tree.
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6.4.11 Ports, Sources and Loads in CADFEKO
Voltage sources and discrete loads are applied to ports and not directly to the model geometry or mesh. A port must be defined before a source or load can be added.
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Adding Waveguide Ports
Define waveguide ports with the correct orientation.
Note: A port is a mathematical representation of where energy can enter (source) or leave a model (sink). Use a port to add sources and discrete loads to a model. Waveguide ports without sources are considered to be absorbing waveguide terminations.
1. Add the first waveguide port on the face at the most positive X position. a) In the 3D view, repeatedly left-click until the face is highlighted.
Figure 143: The face at the most positive X position is selected.
b) Open the Create Waveguide Port dialog using one of the following workflows: · On the Source/Load tab, in the Ports group, click the Waveguide Port icon. · In the details tree, a right-click context menu is available on the face. From the list, click Create Port > Waveguide Port.
Figure 144: The Create Waveguide Port dialog. c) Use the default settings for the port.
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Figure 145: The preview of the waveguide port is displayed in green. Note: The white line is the reference vector and shows the direction of m, where m is the number of half-wavelengths across the width of the waveguide. d) Click Add to add the waveguide port, but do not close the dialog. 2. Add the second waveguide port at the face at the most negative Y position. a) On the dialog, click on the Face user input field to make it active. An active field is highlighted in blue (see Figure 144). b) In the 3D view, repeatedly left-click until the face is highlighted. c) Click Add to add the waveguide port, but do not close the dialog. 3. Add the third waveguide port at the face at the most positive Y position. a) On the dialog, click on the Face field to make it active. An active field is highlighted in blue. b) In the 3D view, repeatedly left-click until the face is highlighted. c) Click 180 degrees to ensure the correct reference direction. d) Click Create to add the port and to close the dialog. 4. Enable the port annotations. On the 3D View context tab, on the Display Options tab, in the Entity Display group, click the Port Annotations icon.
Figure 146: The waveguide power divider with three defined waveguide ports.
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Adding a Waveguide Source
Add a waveguide source to the first port using the fundamental mode.
Note: Default values are used in this example. The fundamental mode for this source will be excited (TE10). Add multiple modes as a single source by selecting Specify modes manually.
1. On the Source/Load tab, in the Sources on Ports group, click the Waveguide Source icon.
2. In the drop-down list, select WvaeguidePort1.
Figure 147: The Create Waveguide Source dialog. 3. Click Create to create the source and to close the dialog.
Figure 148: A port with a source is indicated in red. Proprietary Information of Altair Engineering
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6.4.12 Setting the Simulation Frequency
Specify the frequency range of interest. 1. On the Source/Load tab, in the Settings group, click the
Frequency icon.
A variable was created at the beginning of the example that contains the solution frequency. 2. In the Frequency (Hz) field, enter freq.
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3. Click OK to close the dialog.
With the frequency set to freq, the actual frequency is 9 GHz. In the model tree, click the Configuration tab to view the specified simulation frequency.
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6.4.13 Adding a Near Field Request
Add a near field request to calculate the fields on a surface through the centre of the waveguide. 1. On the Request tab, in the Solution Requests group, click the Near Fields icon. 2. On the Request near fields dialog, enter the values as indicated.
Dimension U V N
Start -10 -20 0
End 30 20 0
Number of Field Points 32 32 1
3. Clear the Sample on edges check box. Note: A near field request on PEC boundaries will result in a warning by the Solver.
4. In the Label field, use the default (NearField1). 5. Click Create to add the near field request and to close the dialog.
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6.4.14 Setting Local Mesh Sizes for Waveguide Port Faces
Refine the mesh locally at the waveguide port faces. The faces for the waveguide ports require a finer mesh to represent the highest mode that should be taken into account. The higher order modes are typically evanescent modes.
1. In the 3D view, select the three waveguide port faces. 2. From the right-click context menu, select Properties. 3. On the Modify Face dialog (Meshing tab), specify the following:
a) Select the Local mesh size check box. b) Set the Mesh size to lambda/20.
Figure 149: The Modify Face (Meshing tab) dialog. 4. Click OK to apply the properties and to close the dialog.
Figure 150: Note the localised mesh refinement at the waveguide port faces. Note: The icon in the details tree indicate that a local mesh setting is applied.
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6.4.15 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Waveguide_Divider.cfx. 3. Click Save to close the dialog.
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6.5 Launching the Solver
Launch the Solver to calculate the results. No requests were added to this model since impedance and current information are calculated automatically for all voltage and current sources in the model.
1. Launch the Solver using one of the following workflows: · On the Solve/Run tab, in the Run/Launch group, click the Feko Solver icon.
· On the application launcher toolbar, click the Feko Solver icon in the
group.
· Press Alt+4 to use the keyboard shortcut. If the model contains unsaved changes, the Save Model dialog is displayed.
2. Click Yes to save the model and to close the Save Model dialog. The Feko Solver is launched and the Executing runfeko dialog is displayed. The dialog gives step-bystep feedback as the simulation progresses.
3. Click Details to expand the Executing runfeko to view the step-by-step feedback.
Figure 151: The Executing runfeko dialog.
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6.6 Launching POSTFEKO
Open POSTFEKO from within CADFEKO. Use one of the following workflows to launch POSTFEKO:
· On the Solve/Run tab, in the Run/Launch group, click the
POSTFEKO icon.
· On the application launcher toolbar, click the POSTFEKO icon in the
group.
· Press Alt+3 to use the keyboard shortcut.
POSTFEKO opens by default with a single 3D view containing the model geometry.
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6.6.1 Viewing the Input Reflection Coefficient
Plot the input reflection coefficient on a Cartesian graph in dB.
The model was solved at a single frequency only. Therefore the graph will contain a single data point. 1. Create a new Cartesian graph. a) On the Home tab, in the Create new display group, click the Cartesian icon.
2. Add the input reflection coefficient to the Cartesian graph. a) On the Home tab, in the Add results group, click the Source data icon. From the dropdown list, select WaveguideSource1.
3. View the input reflection coefficient in dB. a) On the result palette, in the Traces panel, select WaveguideSource1. b) On the Quantity panel, select the dB check box.
4. Change the legend position to top-right. a) On the Display tab, in the Display group, click the Position icon. From the drop-down list select Overlay top right.
5. Remove the graph footer. a) On the Display tab, in the Display group, click the Chart text icon.
b) In the Graph footer field, clear the Auto check box and delete the text. c) Click OK to apply the text changes and to close the dialog.
6. [Optional] Add annotations to the graph. a) On the Cartesian context tab, on the Measure tab, on the Custom annotations group, click the Points icon. From the drop-down list, click Global maximum.
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Note: The power reflected back to Port1 is more than 30 dB lower than the power applied to the same port.
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6.6.2 Viewing the Near Fields
Display the calculated near fields in the 3D view. Animate the instantaneous near field. 1. Select the 3D View1 window. 2. Enable mesh opacity to view the near field inside the waveguide. a) On the 3D View contextual tabs set, on the Mesh tab, in the Opacity group, click the Mesh opacity icon. From the drop-down list, select a value of 40%.
3. On the Home tab, in the Add results group, click the Near Fields icon. From the drop-down list, select NearField1.
4. Animate the phase of the near field. a) In the result palette, in the Quantity panel, select Instantaneous magnitude. b) On the 3D View contextual tabs set, on the Animate tab, on the Settings group, click the Type icon. From the drop-down list, select the Phase icon.
5. Start the animation process. a) On the 3D View contextual tabs set, on the Animate tab, on the Control group, click the Play icon.
b) Stop the animation by clicking the Play icon again.
Figure 152: The near field in the power divider (refer to the WebHelp to view the animation of the instantaneous magnitude).
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6.7 Final Remarks
This example showed the construction, configuration and solution of a waveguide power divider. The model consists of a hollow cuboidal sections with a cylinder (pin) in the centre. The near field and input reflection coefficient was calculated and displayed.
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Optimisation of Bent Dipole and Plate
7 Optimisation of Bent Dipole and Plate
The example considers the optimisation of the gain of a bent dipole in front of a plate.
This chapter covers the following: · 7.1 Example Overview (p. 197) · 7.2 Topics Discussed in this Example (p. 198) · 7.3 Example Prerequisites (p. 199) · 7.4 Creating the Model in CADFEKO (p. 200) · 7.5 Launching the Solver (p. 218) · 7.6 Launching POSTFEKO (p. 219) · 7.7 Closing Remarks (p. 226)
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7.1 Example Overview
Calculate and maximise the gain of a bent dipole in front of a plate. Optimise the dipole-plate separation distance and the dipole bend-angle. The goal is to maximize the maximum gain in the azimuth plane at a single frequency.
Figure 153: Sketch of the model showing dimensions and other relevant parameters.
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7.2 Topics Discussed in this Example
Before starting this example, check if the topics discussed in this example are relevant to the intended application and experience level. The topics discussed in this example are:
· CADFEKO Define an optimisation search in CADFEKO. Run the optimiser (OPTFEKO). Add a wire port to a wire segment. Specify symmetry to save computational resources. Add a voltage source to a wire port. Mesh the model. Run CEM validate to ensure the model is electromagnetically validated. Run the Solver
· POSTFEKO View the optimisation results in POSTFEKO.
Note: Follow the example steps in the order it is presented as each step uses its predecessor as a starting point.
Tip: Find the completed model in the application macro library[25]: GS 7: Optimisation of a Bent Dipole and Plate
25. The application macro library is located on the Home tab, in the Scripting group. Click the Application Macro icon and from the drop-down list, select Getting Started Guide.
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7.3 Example Prerequisites
Before starting this example, ensure that the system satisfies the minimum requirements. The requirements for this example are:
· Feko 2022.1 or later should be installed. · It is recommended that you watch the demo video before attempting this example. · This example should not take longer than 20 minutes to complete.
Note: When using CADFEKO over a remote desktop connection, you may need to enable 3D support for remote desktop[26] for the host's graphics card should a crash occur when clicking New Project in CADFEKO.
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7.4 Creating the Model in CADFEKO
Create the model geometry using the CAD component, CADFEKO.
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7.4.1 Launching CADFEKO (Windows)
There are several options available to launch CADFEKO in Windows. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility.
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Figure 154: The Launcher utility. · Open CADFEKO by double-clicking on a .cfx file. · Open CADFEKO from other components, for example, from inside POSTFEKO or EDITFEKO.
Note: If the application icon is used to launch CADFEKO, no model is loaded and the start page is shown. Launching CADFEKO from other Feko components automatically loads the model.
7.4.2 Launching CADFEKO (Linux)
There are several options available to launch CADFEKO in Linux. Launch CADFEKO using one of the following workflows:
· Open CADFEKO using the Launcher utility. · Open a command terminal. Use the absolute path to the location where the CADFEKO executable
resides, for example: /home/user/2022.1/altair/feko/bin/cadfeko
· Open a command terminal. Source the "initfeko" script using the absolute path to it, for example: . /home/user/2022.1/altair/feko/bin/initfeko
Sourcing initfeko ensures that the correct Feko environment is configured. Type cadfeko and press Enter.
Note: Take note that sourcing a script requires a dot (".") followed by a space (" ") and then the path to initfeko for the changes to be applied to the current shell and not a sub-shell.
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7.4.3 Adding Variables
Define variables to create a parametric model.
A model is parametric when it is created using variable expressions. When a variable expression is modified, any items dependent on that variable are re-evaluated and automatically updated. It is the recommended construction method when creating a model, but not compulsory.
Defined variables are stored as part of the model in the .cfx file.
1. Open the Create Variable dialog using one of the following workflows: · On the Construct tab, in the Define group, click the Add Variable icon.
· On the model tree, a right-click context menu is available on Variables. From the list, select Add Variable.
Figure 155: The model tree (Construction tab). · On the model tree, click the icon. From the drop-down list, select Add Variable.
Figure 156: The drop-down list available in the model tree. · Press # to use the keyboard shortcut. Proprietary Information of Altair Engineering
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2. Create the following variables:
Name alpha alpha_rad d lambda freq
Expression 60 alpha*pi/180 0.25 1 c0/lambda
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Tip: · Click Add to keep the Create Variable dialog open and add more variables. · Click Create to add a variable and close the Create Variable dialog.
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7.4.4 Creating the Bent Dipole
Create the bent dipole using a polyline. To illustrate the usage of custom workplanes, the bent dipole is created using a custom workplane.
1. On the Construct tab, in the Create Curve group, click the Polyline icon.
Figure 157: The Create Polyline dialog showing the default values. Active fields are outlined in yellow.
Note: Default values are used on geometry creation dialogs to allow a preview in the 3D view. You may change the values as required.
Tip: An active field allowing point-entry is indicated by a yellow outline. Point-entry allows a variable or named points to be entered by pressing Ctrl+Shift+left click on a variable or named point in the model tree.
2. Create a polyline. a) Under Corner 1, add the following coordinates: · Corner 1: U: lambda/4*cos(alpha_rad) - d V: 0 N: lambda/4*sin(alpha_rad) b) In the table, click on the second row to make Corner 2 active. Add the following coordinates:
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· Corner 2: U: -d V: 0 N: 0
c) Click Add row for Corner 3. Click on the third row to make Corner 3 active. Add the following coordinates: · Corner 3: U: lambda/4*cos(alpha_rad) - d V: 0 N: -lambda/4*sin(alpha_rad)
d) Set the Label to Bent_dipole.
Figure 158: The bent dipole with corner point on the X axis.
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7.4.5 Creating the Plate
Create the plate with a vertical orientation located at the origin using a rectangle. 1. On the Construct tab, in the Create Surface group, click the Rectangle icon. 2. Create a rectangle using the Base centre, width, depth definition method. a) Base centre (C): (0, 0, 0) b) Width (W): lambda c) Depth (D): lambda d) Label: Reflector
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Figure 159: The Create Rectangle dialog. 3. Modify the orientation of the rectangle.
a) On the Create Rectangle dialog, click the Workplane tab. b) Click Predefine workplane. c) From the drop-down list, select Global YZ. 4. Click Create to create the rectangle and to close the dialog.
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7.4.6 Ports, Sources and Loads in CADFEKO
Voltage sources and discrete loads are applied to ports and not directly to the model geometry or mesh. A port must be defined before a source or load can be added.
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Creating the Port
Define a wire port on the feed pin to excite the dipole. A voltage source will be added to this port.
Note: A port is a mathematical representation of where energy can enter (source) or leave a model (sink). Use a port to add sources and discrete loads to a model.
1. Select the wire where the port is to be added. a) In the model tree, select Bent_dipole. b) In the details tree, select one of the wires of Bent_dipole.
2. Open the Create Wire Port dialog using one of the following workflows: · On the Source/Load tab, in the Ports group, click the Wire Port icon.
· In the details tree, a right-click context menu is available on the wire. From the drop-down list, click Create port > Wire Port.
3. Under Place port on, click Segment.
Figure 160: The Create Wire Port dialog. 4. Under Location on wire, select the option that places the port on the X axis for the selected
wire. 5. Click Create to create the port and to close the dialog.
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Adding a Voltage Source
Add a voltage source to the port of the bent dipole. 1. On the Source/Load tab, in the Sources on Ports group, click the 2. On the Add Voltage Source dialog, use the default settings.
Voltage Source icon.
Figure 161: The Create Voltage Source dialog.
3. Click Create to create the voltage source and to close the dialog.
Note: The Configuration tab was selected automatically when you defined the voltage source. You may also add sources, loads and set the frequency from here.
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7.4.7 Setting the Simulation Frequency
Specify the frequency range of interest. For this example, a single frequency point is used. 1. On the Source/Load tab, in the Settings group, click the Frequency icon.
A variable was created at the beginning of the example that contains the solution frequency. 2. In the Frequency (Hz) field, enter freq.
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Figure 162: The Solution Frequency dialog.
3. Click OK to set the frequency and to close the dialog.
Note: With the frequency set to freq, the actual frequency is 299.792 MHz. In the model tree, click the Configuration to view the specified simulation frequency.
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7.4.8 Requesting Far Fields
Add a far field request (in the azimuth direction) to the model. 1. On the Request tab, in the Solution Requests group, click the
Far Fields icon.
2. On the Request Far fields dialog, click Horizontal cut (UV plane).
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Figure 163: The Request Far Fields dialog. 3. Use the default label. 4. Click Create to create a far field request and to close the dialog.
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7.4.9 Defining an Optimisation Search
Add an optimisation search to maximise the maximum gain in the azimuth direction. 1. On the Request tab, in the Optimisation group, click the Add Search icon.
2. On the Create Optimisation Search dialog, set the Optimisation convergence accuracy to Normal (default).
3. Click Create to create the new optimisation search and to close the dialog.
Figure 164: The Create Optimisation Search dialog.
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7.4.10 Specifying the Optimisation Parameters
Specify the optimisation parameters. Choose from existing variables and specify their minimum and maximum values
1. In the model tree (Construction tab), select the relevant search. On the Request tab, in the Optimisation group, click the Parameters icon.
2. On the Modify Optimisation Parameters dialog, click the Add button to add a second parameter.
3. Populate the fields on the Modify Optimisation Parameters dialog as given in the table.
Variable alpha d
Min value 20 0.7
Max value 110 0.9
Start value 80 0.8
4. Click OK to set the parameters and to close the dialog.
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7.4.11 Specifying the Far Field Goal
Specify the goal focus, the operations to perform on the goal, and the goal objective. 1. In the model tree, on the Construction tab, select OptimisationSearch1. 2. On the Request tab, in the Optimisation group, click the Add goal function icon. From the
drop down list, select Far Field Source.
3. Under Goal focus, specify the requested output from the Solver. a) Under Focus source type, select Defined in CADFEKO. b) In the Focus source field, from the drop-down list, select FarField1. c) In the Focus type field, from the drop-down list select Gain. d) In the Polarisation field, from the drop-down list select Total.
4. Under Focus processing steps, specify the processing to be performed prior to comparing with the objective. a) In the Operation column, from the drop-down list, select Max.
5. Under Goal operator, specify how the objective and focus is compared. a) In the Operator type drop-down list, select Maximise to maximise the gain. · The Goal objective is the value or values with which the focus is compared. For maximisation and minimisation the Goal objective is hidden. · For multiple goals, the Weight will determine the contribution of the particular goal to the global error function during the fitness evaluation.
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Figure 165: The Create Far Field Goal dialog. 6. Click Create to create the new far field goal and to close the dialog.
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7.4.12 Modifying the Auto-Generated Mesh
When the frequency is set or local mesh settings are applied to the geometry, the automatic mesh algorithm calculates and creates the mesh automatically while the GUI is active using default mesh settings. When required, these mesh settings may be modified.
1. Open the Modify Mesh Settings dialog using one of the following workflows: · On the Mesh tab, in the Meshing group, click the Modify Mesh icon.
· Press Ctrl+M to use the keyboard shortcut. 2. On the Modify Mesh Settings, set the Mesh size to Coarse. 3. Set the Wire segment radius to 0.001.
Figure 166: The Modify Mesh Settings dialog. 4. Click OK to create the mesh and to close the dialog.
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7.4.13 Saving the Model
Save the model to a CADFEKO.cfx file. 1. Save the model using one of the following workflows: · On the Home tab, in the File group, click the Save icon. · Press Ctrl+S to use the keyboard shortcut. 2. Save the model as Dipole_Optimisation.cfx. 3. Click Save to close the dialog.
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7.5 Launching the Solver
Launch the Solver to calculate the results. No requests were added to this model since impedance and current information are calculated automatically for all voltage and current sources in the model.
1. Launch the Solver using one of the following workflows: · On the Solve/Run tab, in the Run/Launch group, click the Feko Solver icon.
· On the application launcher toolbar, click the Feko Solver icon in the
group.
· Press Alt+4 to use the keyboard shortcut. If the model contains unsaved changes, the Save Model dialog is displayed.
2. Click Yes to save the model and to close the Save Model dialog. The Feko Solver is launched and the Executing runfeko dialog is displayed. The dialog gives step-bystep feedback as the simulation progresses.
3. Click Details to expand the Executing runfeko to view the step-by-step feedback.
Figure 167: The Executing runfeko dialog.
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7.6 Launching POSTFEKO
Open POSTFEKO from within CADFEKO. Use one of the following workflows to launch POSTFEKO:
· On the Solve/Run tab, in the Run/Launch group, click the
POSTFEKO icon.
· On the application launcher toolbar, click the POSTFEKO icon in the
group.
· Press Alt+3 to use the keyboard shortcut.
POSTFEKO opens by default with a single 3D view containing the model geometry.
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7.6.1 Setting Up POSTFEKO to View Optimisation Progress
Create a 3D view with the far field results as well as two Cartesian graph to view the distance parameter and far field goal. When POSTFEKO is opened, the model is displayed in a single 3D view.
1. Display the far field in the 3D view. a) On the Home tab, in the Add results group, click the Far Field Source icon. b) From the drop-down list select FarField1.
Figure 168: The far field result for the bent dipole and plate.
2. Add a Cartesian graph and view the optimised parameter, alpha. a) On the Home tab, in the Create new display group, click the
Cartesian icon.
b) On the Home tab, in the Add results group, click the drop-down list, select Optimisation.
c) In the result palette, in the Trace list, select alpha.
Optimisation icon. From the
Figure 169: The Optimisation panel in the result palette. 3. Duplicate the first graph (to create a second graph) to view the optimised parameter, d.
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a) On the 3D View contextual tabs set, on the Display tab, in the Duplicate group, click the Duplicate view icon.
b) In the result palette select the trace, Optimisation. c) In the result palette, in the Trace field, select d. 4. Duplicate the first graph (to create the third graph) and view the far field goal versus optimisation run number. a) On the 3D View contextual tabs set, on the Display tab, in the Duplicate group, click the
Duplicate view icon.
b) In the result palette select the trace, Optimisation. c) In the result palette, in the Trace field, select search1.goals.farfieldgoal1. 5. [Optional] Arrange (tile) the four windows to view the multiple windows at once. a) On the View tab, in the Window, click the Tile icon.
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7.6.2 Launching OPTFEKO
Run OPTFEKO and view the output of the optimisation progress. The following steps are performed in POSTFEKO, but the optimiser can also be launched from CADFEKO
1. On the Home tab, in the Run/Launch group, click the Optimisation icon.
Note: The Executing optfeko dialog is displayed in a condensed format. Click Details to view any problems encountered during the optimisation process.
Figure 170: The Executing optfeko dialog in condensed format.
2. Scroll to the bottom of the Executing optfeko window output to view the onvergence information, as well as the optimal parameters.
Note: Sensitivity information is included if sufficient data is available for the analysis.
Figure 171: The Executing optfeko dialog with details. The Executing optfeko window displays the optimum values as follows:
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· alpha: 82.349° · d: 0.783 meters
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7.6.3 Viewing the Optimisation Results
View the optimisation results obtained by OPTFEKO. The graphs have already been configured to view the progress of the optimisation process. View the final results of OPTFEKO for the optimisation parameters on the previously defined 3D view and 2D graphs.
Figure 172: The optimisation run number on a Cartesian graph.
Note: For more details on the optimisation process, view the log file, Dipole_Optimisation.log, that was created in the same directory as the current model. OPTFEKO creates multiple CADFEKO (.cfx) models for each iteration, located in the same directory as the current model. For example: Dipole Optimisation_opt_1.cfx Dipole Optimisation_opt_2.cfx Dipole Optimisation_opt_3.cfx . . Dipole Optimisation_opt_17.cfx including the model with the variables set to the optimum values (indicated by the _optimum file extension). Dipole_Optimisation_optimum.cfx
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Figure 173: The optimised far field for the bent dipole and plate.
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7.7 Closing Remarks
This example showed the construction and optimisation of a bent dipole in front of a plate.
Many concepts were introduced in this simple example that are applicable to models commonly created in CADFEKO. This example has demonstrated how to configure a CADFEKO model as well as how optimisation in CADFEKO is executed. The optimisation process as well as the optimum values for the model parameters were displayed in POSTFEKO, but can also be viewed in the .log file.
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Index
Special Characters
.cfx file import 127
Numerics
2D graph 33 3D view 20, 33, 67
A
align tool 131
antenna placement 131 application launcher toolbar 20, 33 application menu 23
B
bent dipole 204 boolean operation 70
C
CADFEKO graphical user interface 13 introduction 17
calculate 110, 134, 159, 190, 218 Cartesian graph 39, 113, 115, 162, 163, 164, 192 CEM validation 27 complex load 153 component library 125 configuration list 20 Configuration tab 20, 26 configurations
multiple 20 Construction tab 20, 24 contextual tab 20, 33 contextual tab set 20, 23, 33 continuous (interpolated) range 155 core tab 20, 23, 33 cuboid 89, 176 current 162 custom
keyboard shortcuts 29 mouse bindings 30
227
cylinder 175
D
data 110, 134, 159, 190, 218 delete
face 63 details browser 33 details tree 20, 89 dialog launcher 23 dielectric 85, 89, 90 dielectric loss tangent 85 dipole 204 display
mesh edges 36 sources 36 symmetry planes 36 drone 125
E
ellipse create 69
end frequency 155 error feedback 28
F
face delete 63
face medium set 94
face properties 94 faces
redundant 179 far field
left-hand circular 115 request 211 right-hand circular 115 far field (2D) 37 far field (3D) 37 far field request 104 feed 65, 92 feed pin create 92 Feko components 16 flare create 60
228
format graph 164 frequency
end 155 simulation 186 single 71, 210 start 155
G
graph add arrow 164 add circle 164 add rectangle 164 Cartesian 162, 163, 164, 192 footer 162
graphical user interface CADFEKO 13 POSTFEKO 13
ground plane infinite 147
H
help 20, 33 hide
simulation mesh 128, 131 highlight 67 hole
create 70 Home tab 23
I
impedance input 113, 163
import .cfx 127
infinite ground plane 147 input impedance 163 introduction 17, 31
K
kernel 110, 134, 159, 190, 218 keyboard shortcuts
custom 29 keytip 23
229
L
launch CADFEKO 18, 18, 49, 49, 79, 79, 123, 123, 143, 143, 171, 171, 201, 201
legend position 162
line create 58, 65
line colour 164 Linux 18, 49, 79, 123, 143, 171, 201 load
complex 153 local mesh size 102, 188 local wire radius 144, 157 Lua script
graph 136
M
macro recording activate 80 deactivate 105
marker colour 164 marker style 164 medium 85 mesh
local 102, 188 local wire radius 157 mesh connectivity 62, 66, 93, 178 message bubble 28 model parametric 51, 82, 173, 202 model browser 33 model status 20 model tree 89 model unit 81, 124, 172 monopole 149 mouse bindings custom 30 multiple configurations 20
N
near field request 187, 194
near field (2D) 37 near field (3D) 37 notes view 20
230
notification centre 20 Notification centre 27
O
opacity 63, 65 OPTFEKO 222 optimisation
far field goal 214 parameters 213 result 224 search 212 overlay 128, 131
P
parametric model 51, 82, 173, 202
patch 86 path sweep 59 PEC 89 PEC ground plane 147 perfect electric conductor 89 perfect electric conductor (PEC) 94 pin
power dividing 175 placement
antenna 131 planar multilayer substrate 89 point-entry 36, 56, 69 polar graph 43 polygon 86 polyline 146, 204 port
waveguide 183 wire 97, 149, 151, 208 POSTFEKO graphical user interface 13 introduction 31 power 152, 154 power dividing pin 175 project browser 33
Q
quadcopter 125 quick access toolbar 20, 33
231
R
radiated power level 154 rectangle
create 56 reflection coefficient 113, 192 region 89, 180 region medium
set 90 region properties 90 relative permittivity 85 request
far field 104, 211 near field 187, 194 resistive load 153 result palette 33 results optimisation 224 ribbon 20, 23, 33 ribbon group 23 rotate 131
S
save 72, 109, 133, 158, 189, 217 script 136 search
optimisation 212 search bar 20, 33 selection
auto 67 edges/wires 67 faces 67 geometry parts 67 mesh element 67 mesh label 67 mesh parts 67 mesh vertex 67 regions 67 shapes 164 shell 180 show simulation mesh 128, 131 simplify 178, 179 simulation frequency 71, 99, 155, 210 simulation frequency (single) 186 simulation mesh 128, 131 snapping 128, 131
232
snapping points 65, 69 soft message bubble 28 solver 110, 134, 159, 190, 218 Solver 16 source
voltage 98, 152, 209 waveguide 185 start CADFEKO 18, 18, 49, 49, 79, 79, 123, 123, 143, 143, 171, 171, 201, 201 start frequency 155 start page 19 status bar 20, 33 substrate finite 89 infinite 89 subtract from 70
T
tab Home 23
tool align 131 cuboid 89 frequency 99 macro recording 80, 105 polygon 86 save 72, 109, 133, 158, 189, 217 union 93 voltage source 98 wire port 97
total source power 154 transform 131 transmission line 146, 151 transparency 63, 65
U
union 62, 66, 93, 128, 131, 178, 181
V
validate model 36 validation 27 variable 51, 82, 173, 202 view data 162 voltage source 98, 152, 209
233
W
waveguide 176, 180 waveguide port 183 waveguide source 185 Windows 18, 49, 79, 123, 143, 171, 201 wire
create 58, 65 wire feed 65 wire port 97, 149, 151, 208 wire radius
local 144 wire segment radius 100, 156 workflow 13, 16 workplane
define 53 snap to point 65
Z
zoom to extents 144, 175
234
Apache FOP Version 2.2 DITA Open Toolkit