RF Exposure calculation

FCC ID: RRK2003060017-3

RF Exposure Info

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FCCID_411639

FCC ID: RRK2003060017-3 RF EXPOSURE REPORT REPORT NO.: SA930303R02 MODEL NO.: Gateway 7001 802.11A+G Wireless Access Point ACCORDING: FCC Guidelines for Human Exposure IEEE C95.1 APPLICANT: Alpha Networks Inc. ADDRESS: No.8, Li-shing 7th Rd., Science-based Industrial Park, Hsinchu, Taiwan, R.O.C. ISSUED BY: Advance Data Technology Corporation LAB LOCATION: 47 14th Lin, Chiapau Tsun, Linko, Taipei, Taiwan, R.O.C. Report No: SA930303R02 1

FCC ID: RRK2003060017-3 RF Exposure Measurement (Mobile Device) 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: SA930303R02 2

FCC ID: RRK2003060017-3 3. Friis Formula Friis transmission formula : Pd = (Pout*G) / (4*pi*r2) 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 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: SA930303R02 3

FCC ID: RRK2003060017-3 6 Test Results 6.1 Antenna Gain The maximum Gain measured in Fully Anechoic Chamber are 2dBi or 1.585 (numeric) for 2.4GHz and 5GHz. 6.2 Output Power Into Antenna & RF Exposure value at distance 20cm: For 802.11b (2.4GHz Band): Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 30.130 0.010 1.0 6 2437 35.727 0.011 1.0 11 2462 39.811 0.013 1.0 For 802.11g (2.4GHz Band): Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 35.481 0.011 1.0 6 2437 44.668 0.014 1.0 11 2462 39.811 0.013 1.0 For 802.11a (5.15~5.35GHz): Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 5180 36.813 0.012 1.0 4 5240 35.727 0.011 1.0 5 5260 39.902 0.013 1.0 8 5320 40.365 0.013 1.0 For 802.11a (5.725~5.850GHz): Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 9 5745 77.090 0.024 1.0 11 5785 73.621 0.023 1.0 13 5825 74.989 0.024 1.0 Note: Both of the 2.4GHz and 5GHz bands can transmit simultaneously, the maximum power density value is 0.038 mW/cm2, which is less than the 1mW/cm2 limit. Report No: SA930303R02 4


Document Created: 2004-04-05 17:38:09
Document Modified: 2004-04-05 17:38:09
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