MPE Calculation

FCC ID: PPD-AR5BDT92

RF Exposure Info

Download: PDF
FCCID_1089379

RF EXPOSURE REPORT REPORT NO.: SA980302H02 MODEL NO.: AR5BDT92 ACCORDING: FCC Guidelines for Human Exposure IEEE C95.1 APPLICANT: Atheros Communications, Inc. ADDRESS: 5480 Great America Parkway, Santa Clara, CA 95054 ISSUED BY: Bureau Veritas Consumer Products Services (H.K.) Ltd., Taoyuan Branch LAB LOCATION: No. 81-1, Lu Liao Keng, 9th Ling,Wu Lung Tsuen, Chiung Lin Hsiang, Hsin Chu Hsien 307, Taiwan Report No.: SA980302H02 1 Report Format Version 3.0.0

RF Exposure Measurement 1. Introduction In this document, we try to prove the safety of radiation harmfulness to the human body for our product. The limit for Maximum Permissible Exposure (MPE) specified in FCC 1.1310 is followed. The Gain of the antenna used in this product is measured in a Fully Anechoic Chamber (FAC) calibrated for antenna measurement in ADT, and also the maximum total power input to the antenna is measured. Through the Friis transmission formula and the maximum gain of the antenna, we can calculate the distance, away from the product, where the limit of MPE is reached. Although the Friis transmission formula is a far field assumption, the calculated result of that is an over-prediction for near field power density. We will take that as the worst case to specify the safety range. 2. RF Exposure Limit According to FCC 1.1310: The criteria listed in the following table shall be used to evaluate the environmental impact of human exposure to radio-frequency (RF) radiation as specified in 1.1307(b) LIMITS FOR MAXIMUM PERMISSIBLE EXPOSURE (MPE) Frequency Electric Field Magnetic Field Power Density Average Time 2 Range Strength (V/m) Strength (A/m) (mW/cm ) (minutes) (MHz) (A)Limits For Occupational / Control Exposures 300-1500 … … F/300 6 1500-100,000 … … 5 6 (B)Limits For General Population / Uncontrolled Exposure 300-1500 … … F/1500 6 1500-100,000 … … 1.0 30 F = Frequency in MHz Report No.: SA980302H02 2 Report Format Version 3.0.0

3. Friis Formula Friis transmission formula : Pd = (Pout*G) / (4*pi*r 2) where Pd = power density in mW/cm2 Pout = output power to antenna in mW G = gain of antenna in linear scale Pi = 3.1416 R = distance between observation point and center of the radiator in cm Pd is the limit of MPE, 1 mW/cm2. If we know the maximum Gain of the antenna and the total power input to the antenna, through the calculation, we will know the MPE value at distance 20cm. Ref. : David K. Cheng, Field and Wave Electromagnetics, Second Edition, Page 640, Eq. (11-133). 4. EUT Operating condition The software provided by Manufacturer enabled the EUT to transmit and receive data at lowest, middle and highest channel individually. 5. Classification The antenna of this product, under normal use condition, is at least 20cm away from the body of the user. Warning statement to the user for keeping at least 20cm or more separation distance with the antenna should be included in users manual. So, this device is classified as Mobile Device Report No.: SA980302H02 3 Report Format Version 3.0.0

6. Test Results 6.1 Antenna Gain There are two antennas provided to this EUT, please refer to the following table: Antenna Antenna Transmitter Antenna Antenna Brand Model Gain (dBi) Gain (dBi) Circuit Type Connector For 2.4GHz For 5GHz Chain(0) Tyco 1513327-1 Dipole 3 4 RPSMA Chain(1) Tyco 1513327-1 Dipole 3 4 RPSMA 6.2 Output Power Into Antenna & RF Exposure value at distance 20cm: For 15.247(2.4GHz) : For Part 802.11b: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 214.815 0.085 1.0 6 2437 193.670 0.077 1.0 11 2462 183.458 0.073 1.0 For Part 802.11g: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 669.196 0.266 1.0 6 2437 785.481 0.312 1.0 11 2462 587.573 0.233 1.0 DRAFT 802.11n (20MHz) OFDM Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 738.015 0.293 1.0 6 2437 784.234 0.311 1.0 11 2462 616.770 0.245 1.0 DRAFT 802.11n (40MHz) OFDM Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2422 519.278 0.206 1.0 4 2437 882.267 0.350 1.0 7 2452 555.291 0.220 1.0 Report No.: SA980302H02 4 Report Format Version 3.0.0

For 15.247(5GHz) : For Part 802.11a: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5745 414.769 0.414 1.0 3 5785 400.550 0.399 1.0 5 5825 376.428 0.375 1.0 For DRAFT 802.11n (20MHz) OFDM: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5745 417.146 0.208 1.0 3 5785 406.501 0.203 1.0 5 5825 377.129 0.188 1.0 DRAFT 802.11n (40MHz) OFDM Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5755 433.680 0.217 1.0 3 5795 409.566 0.205 1.0 Report No.: SA980302H02 5 Report Format Version 3.0.0

For 15.407(5GHz) : For Part 802.11a: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5180 28.027 0.028 1.0 2 5200 27.019 0.027 1.0 4 5240 27.297 0.027 1.0 5 5260 101.983 0.102 1.0 7 5300 101.873 0.102 1.0 8 5320 83.773 0.084 1.0 9 5500 44.903 0.045 1.0 14 5600 101.400 0.101 1.0 19 5700 54.960 0.055 1.0 For DRAFT 802.11n (20MHz) OFDM: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5180 39.060 0.020 1.0 2 5200 33.731 0.017 1.0 4 5240 34.918 0.017 1.0 5 5260 106.429 0.053 1.0 7 5300 102.694 0.051 1.0 8 5320 112.601 0.056 1.0 9 5500 66.119 0.033 1.0 14 5600 104.252 0.052 1.0 19 5700 47.066 0.024 1.0 DRAFT 802.11n (40MHz) OFDM Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5190 47.161 0.024 1.0 2 5230 44.844 0.022 1.0 3 5270 106.702 0.053 1.0 4 5310 44.239 0.022 1.0 5 5510 30.174 0.015 1.0 7 5590 106.796 0.053 1.0 9 5670 78.550 0.039 1.0 Report No.: SA980302H02 6 Report Format Version 3.0.0


Document Created: 2009-03-19 19:42:36
Document Modified: 2009-03-19 19:42:36
© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC