User guide

March 2005 Building Your Canopy Network
Through Software Release 6.1
Page 128 of 425 Issue 1
Canopy System User Guide
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:
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 gives
P G
.
4
π
d
S
=
Calculated Distances and Power Compliance Margins
TBL shows calculated minimum separation distances d, recommended distances and
resulting power compliance margins for each frequency band and antenna combination.
Table 34: Power Compliance Margins
Variable
Frequency
Band
Antenna
P G
S
d
1
Recom-
mended
Distance
Power
Compliance
Margin
900 MHz external
0.4 W
(26 dBm)
10.0
(10 dB)
6
W/
m
2
0.23 m
60 cm
(24 in)
7
internal
0.34 W
(25 dBm)
6.3
(8 dB)
10
W/
m
2
0.13 m
20 cm
(8 in)
2.3
2.4 GHz
internal
+
reflector
0.34 W
(25 dBm)
79.4
(19 dB)
10
W/
m
2
0.46 m
1.5 m
(5 ft)
10
internal
0.2 W
(23 dBm)
5.0
(7 dB)
10
W/
m
2
0.09 m
20 cm
(8 in)
5
5.2 GHz
internal
+
reflector
0.0032 W
(5 dBm)
316
(25 dB)
10
W/
m
2
0.09 m
1.5 m
(5 ft)
280
S =
P
• G
4 π d
2