RF Exposure

FCC ID: H8NBTM010

RF Exposure Info

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FCCID_329921

FCC TEST REPORT REPORT NO.: RF920318R02 MODEL NO.: BTM010 ACCORDING: FCC Guidelines for Human Exposure IEEE C95.1 APPLICANT: ASKEY COMPUTER CORP. ADDRESS: 10F, 119, CHIENKANG RD., CHUNG-HO, TAIPEI, TAIWAN, 235, R.O.C. ISSUED BY: Advance Data Technology Corporation LAB LOCATION: 47 14th Lin, Chiapau Tsun, Linko, Taipei, Taiwan, R.O.C. 0528 Lab Code: 200102-0 ILAC MRA ADT No: 920318R02 1

RF Exposure Measurement 1. Introduction 2.4 GHz frequency band is regarded specially as a dangerous band for its heating harmfulness to the human body. That’s why microwave oven is operating in this frequency band. The manufacturer whose product is working in this frequency band is obligatory to prove the harmfulness of his product. 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 ADT No: 920318R02 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 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 distance r where the MPE limit is reached. 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 Climate Condition The temperature and related humidity: 20 deg. C and 50 % RH 6. Classification This device is not fixed inside the host equipment, it is connected with host through wire. So it is easy to be re-located in the place where at least 20 cm far 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. ADT No: 920318R02 3

7 Test Results 7.1 Antenna Gain The maximum Gain measured in Fully Anechoic Chamber is 1dBi or 1.258 (numeric). 7.2 Output Power Into Antenna & RF Exposure Distance : MINIMUM ALLOWABLE CHANNEL OUTPUT POWER DISTANCE ( r ) CHANNEL FREQUENCY TO ANTENNA (mW) FROM SKIN (MHz) (Centi-Meter) 0 2402 2.56 0.51 39 2441 2.05 0.45 78 2480 1.58 0.40 The minimum allowable distance is very close to the enclosure of the antenna. So, the user has no need to worry about the harmfulness of radiation. But it is recommended to always keep, at least, 20cm separation distance with the antenna. ADT No: 920318R02 4


Document Created: 2003-04-29 15:52:44
Document Modified: 2003-04-29 15:52:44
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