RF Exposure Evaluation
FCC ID: 2APYY-WS21004
1 Measuring Standard
KDB 680106 D01 RF Exposure Wireless Charging Apps v03 r01
2 Requirements
According to item 5 of KDB 680106 D01v03 r01, inductive wireless power transfer applications that meet all of the following requirements are excluded from submitting an RF exposure evaluation:
- (1) Power transfer frequency is less than 1MHz.
- (2) Output power from each primary coil is less than or equal to 15 watts.
- (3) The system may consist of more than one source primary coils, charging one or more clients. If more than one primary coil is present, the coil pairs may be powered on at the same time.
- (4) Client device is placed directly in contact with the transmitter.
- (5) Mobile exposure conditions only (portable exposure conditions are not covered by this exclusion).
- (6) The aggregate H-field strengths at 15 cm surrounding the device and 20 cm above the top surface from all simultaneous transmitting coils are demonstrated to be less than 50% of the MPE limit.
Remark: Meet all the above requirements.
3 Limits
The criteria listed in the following table shall be used to evaluate the environment impact of human exposure to radio frequency (RF) radiation as specified in 1.1307(b).
Limits for Maximum Permissible Exposure (MPE)
(A) Limits for Occupational/Controlled Exposures
| Frequency range (MHz) | Electric field strength (V/m) | Magnetic field strength (A/m) | Power density (mW/cm²) | Averaging time (minutes) |
|---|---|---|---|---|
| 0.3-3.0 | 614 | 1.63 | *(100) | 6 |
| 3.0-30 | 1842/f | 4.89/f | *(900/f²) | 6 |
| 30-300 | 61.4 | 0.163 | 1.0 | 6 |
| 300-1500 | - | - | f/300 | 6 |
| 1500-100,000 | - | - | 5 | 6 |
(B) Limits for General Population/Uncontrolled Exposure
| Frequency range (MHz) | Electric field strength (V/m) | Magnetic field strength (A/m) | Power density (mW/cm²) | Averaging time (minutes) |
|---|---|---|---|---|
| 0.3-1.34 | 614 | 1.63 | *(100) | 30 |
| 1.34-30 | 824/f | 2.19/f | *(180/f²) | 30 |
| 30-300 | 27.5 | 0.073 | 0.2 | 30 |
| 300-1500 | - | - | 1/1500 | 30 |
| 1500-100,000 | - | - | 1.0 | 30 |
Notes:
- f = frequency in MHz
- *-Plane-wave equivalent power density
- RF exposure compliance will need to be determined with respect to 1.1307(c) and (d) of the FCC rules.
- The emissions should be within the limits at 300kHz in Table 1 of 1.1310 (use the 300kHz limits for 150kHz: 614V/m, 1.63A/m).
4 Test Setup
Diagram illustrating the test setup. It shows the EUT (Equipment Under Test) with positions labeled A (Left), B (Right), C (Top), D (Front), and E (Rear). A probe is positioned at 15 cm from the sides and 20 cm from the top of the EUT.
5 Test Procedure
- The RF exposure test was performed in anechoic chamber.
- The measurement probe was placed at test distance (15 cm from all sides and 20 cm from the top) which is between the edge of the charger and the geometric center of probe.
- The highest emission level was recorded and compared with limit as soon as measurement of each points (A, B, C, D, E) were completed.
- The EUT was measured according to the dictates of KDB 680106 D01v03 r01.
Remark: The EUT's test position A, B, C, D and E is valid for the E and H field measurements.
Note: Wireless Output: DC9V/1.1A and DC5V/1A all have been tested, only worse case DC9V/1.1A is reported.
6 Test Instruments
| Test Equipment | Manufacturer | Model No. | SN. | Cal. Date (mm-dd-yy) | Cal. Due date (mm-dd-yy) |
|---|---|---|---|---|---|
| EMF Meter | NARDA | ELT-400 | N-0356 | Oct 08, 2022 | Oct 07, 2023 |
| EMF probe | NARDA | B-Field Probe | M-0812 | Oct 08, 2022 | Oct 07, 2023 |
7 Test Result
Note: Frequency Range 0.1115-0.205 (MHz); <5% load energy, 50% load energy, >90% load energy mode all have been tested. Only worse case Max load mode (<5% load energy) is reported.
E-Field Strength at 15 cm from the edges surrounding the EUT (V/m)
| Frequency Range (MHz) | Test Position A | Test Position B | Test Position C | Test Position D | Limits (V/m) |
|---|---|---|---|---|---|
| 0.1115-0.205 | 1.89 | 1.8 | 1.83 | 1.77 | 614 |
E-Field Strength at 20 cm from the top of the EUT (V/m)
| Frequency Range (MHz) | Test Position E | Limits (V/m) |
|---|---|---|
| 0.1115-0.205 | 1.70 | 614 |
H-Field Strength at 15 cm from the edges surrounding the EUT (A/m)
| Frequency Range (MHz) | Test Position A | Test Position B | Test Position C | Test Position D | Limits (A/m) |
|---|---|---|---|---|---|
| 0.1115-0.205 | 0.55 | 0.51 | 0.49 | 0.48 | 1.63 |
H-Field Strength at 20 cm from the top of the EUT (A/m)
| Frequency Range (MHz) | Test Position E | Limits (A/m) |
|---|---|---|
| 0.1115-0.205 | 0.41 | 1.63 |
