Table 9: Calculated Exposure Distances And Power Compliance Margins - Motorola 5440AP - Canopy 5.4 GHz AP User Manual Supplement

Canopy 400 Series OFDM AP and SM
ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines
•
for the general public. See the ICNIRP web site at
Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and
Electromagnetic Fields.
The applicable power density exposure limits from the documents referenced above are
10 W/m
•
Peak power density in the far field of a radio frequency point source is calculated as follows:
S =
4 # d
Rearranging terms to solve for distance yields
!
Table 9 shows calculated minimum separation distances d, recommended distances and
resulting power compliance margins for each frequency band and antenna combination.

Table 9: Calculated Exposure Distances and Power Compliance Margins

Frequency
Band
5.4 GHz
The "Recommended Distances" are chosen to give significant compliance margin in all cases.
They are also chosen so that an OFDM module has the same exposure distance as a Canopy
module, to simplify communicating and heeding exposure distances in the field.
These are conservative distances:
They are along the beam direction (the direction of greatest energy). Exposure to the
•
sides and back of the module will be significantly less.
They meet sustained exposure limits for the general population (not just short term
•
occupational exposure limits), with considerable margin.
The calculated compliance distance d is overestimated because the far-field equation
•
models the antenna as a point source and neglects the physical dimension of the
antenna.
Version 1, April 2008
2
for RF energy in the 5.4-GHz frequency bands.
where
P " G
S = power density in W/m
P = RMS transmit power capability of the radio, in W
2
G = total Tx gain as a factor, converted from dB
d = distance from point source, in m
!
Antenna Variable
P
Integrated, 0.05 W
17 dBi (10 dBm)
Connectori 0.05 W
zed, 17 dBi (10 dBm)
http://www.icnirp.de/
2
P " G
d =
4 # S
d
(calcu-
G S
lated)
5.0 10 6 cm
2
(17 dB) W/m
316 10 6 cm
2
(17 dB) W/m
User Guide
and
Recom- Power
mended Compliance
Separation Margin
Distance
20 cm 10
(8 in)
20 cm 10
(8 in)
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