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B-3
D-620605-0-20 Rev A
CONFIDENTIAL
B.2
Human Exposure to RF
The U.S. Federal Communications Commission (FCC) has adopted limits of human
exposure to radio frequency (RF) emissions from portable or fixed RF systems that
are regulated by the FCC. The exposure limits on the incident electric and magnetic
fields and power densities are based on ANSI/IEEE and NCRP RF Safety Guidelines.
The limits are also prescribed in terms of the mass-normalized rates of internal energy
absorption by tissues (specific absorption rates or SARs) which should not exceed
0.08 W/kg as averaged over the whole body and 1.6 W/kg for any 1-g of tissue.
Similarly, the U.K. National Radiological Protection Board (NRPB) and the Interna-
tional Commission on Non-Ionizing Radiation Protection (ICNIRP) have both estab-
lished guidelines for maximum RF exposure levels that are likely to not pose health
risks. For the general public, ICNIRP recommends maximum exposure levels of
2.0 W/kg for any 10-g of tissue. This recommendation is 5 times lower than that of
NRPB.
The specific absorption rate (SAR) was measured for a radiated power of 20 dBm
(100 mW) which is the maximum radiated for both of the antennas. The highest SAR
regions for each of the antennas for separation distances of 0, 1, 2, and 3 cm to the tis-
sue-simulant model were determined in the first instance by using a coarser sampling
with a step size of 8.0 mm over three overlapping scan areas for a total scan area of
8.0
×
9.6 cm. After identifying the regions of the highest SAR for each of the cases,
the SAR distributions were measured with a resolution of 2 mm in order to obtain the
peak 1 cm 3 or 1-g SAR.
Antenna gain is restricted to 1.5 W ERP (2.49 W EIRP) in order to satisfy RF expo-
sure compliance requirements. If higher than 1.5 W ERP, routine MPE evaluation is
needed. The antennas should be installed to provide at least 20 cm from all persons to
satisfy MPE requirements of FCC Part 2, 2.1091.
