RF exposure calculation

FCC ID: H8NWLH0020

RF Exposure Info

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FCCID_335405

RF EXPOSURE REPORT REPORT NO.: RF920523R04 MODEL NO.: WLH0020 ACCORDING: FCC Guidelines for Human Exposure IEEE C95.1 APPLICANT: ASKEY COMPUTER CORP. ADDRESS: 10F, NO. 119, CHIENKANG RD., CHUNG-HO, TAIPEI TAIWAN R.O.C ISSUED BY: Advance Data Technology Corporation LAB LOCATION: 47 14th Lin, Chiapau Tsun, Linko, Taipei, Taiwan, R.O.C. 0528 ILAC MRA Lab Code: 200102-0 Report No: 920523R04 1

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 Range Strength (V/m) Strength (A/m) (mW/cm2) (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: 920523R04 2

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 r. 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: 920523R04 3

6 Test Results 6.1 Antenna Gain The maximum Gain measured in Fully Anechoic Chamber are 1.8dBi or 1.51 (numeric). 6.2 Output Power Into Antenna & RF Exposure value at distance 20cm: Channel Limit of Output Power to Power Density Channel Frequency Power Density Antenna (mW) (mW/cm2) (MHz) (mW/cm2) 1 2412 34.119 0.0102 1.0 6 2437 31.405 0.0094 1.0 11 2462 32.809 0.0099 1.0 Report No: 920523R04 4


Document Created: 2003-06-13 13:15:15
Document Modified: 2003-06-13 13:15:15
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