User guide

Release 9.4.2 Release Notes
Issue 1, May 2009 Page 41
Antenna of connectorized or integrated 900 MHz
module
At least 60 sm (24 in)
Indoor 900 MHz SM
At least 10 cm (4 in)
The following section and its Table 14 provide details and discussion of the associated
calculations.
10.3.1 Details of Exposure Separation Distances Calculations and Power
Compliance Margins
Limits and guidelines for RF exposure come from:
 US FCC limits for the general population. See the FCC web site at
http://www.fcc.gov, and the policies, guidelines, and requirements in Part 1 of
Title 47 of the Code of Federal Regulations, as well as the guidelines and
suggestions for evaluating compliance in FCC OET Bulletin 65.
 Health Canada limits for the general population. See the Health Canada web
site at http://www.hc-sc.gc.ca/rpb and Safety Code 6.
 ICNIRP (International Commission on Non-Ionizing Radiation Protection)
guidelines for the general public. See the ICNIRP web site at
http://www.icnirp.de/ and Guidelines for Limiting Exposure to Time-Varying
Electric, Magnetic, and Electromagnetic Fields.
The applicable power density exposure limits from the documents referenced above are
 6 W/m
2
for RF energy in the 900-MHz frequency band in the US and
Canada.
 10 W/m
2
for RF energy in the 2.4-, 5.2-, 5.4-, and 5.7-GHz frequency bands.
Peak power density in the far field of a radio frequency point source is calculated as follows:
!
S =
P " G
4 # d
2
where
S = power density in W/m
2
P = RMS transmit power capability of the radio, in W
G = total Tx gain as a factor, converted from dB
d = distance from point source, in m
Rearranging terms to solve for distance yields
!
d =
P " G
4 # S
Table 14 shows calculated minimum separation distances d, recommended distances and
resulting power compliance margins for each frequency band and antenna combination.
Table 14: Calculated exposure distances and power compliance margins
Variable
Band
Antenna
P
G
S
d
(calcu-
lated)
Recom-
mended
Separation
Distance
Power
Compliance
Margin