Product Info

T6-D-USER-AV100-EN Annex Page 4
© Park Air Systems Limited 2020
United States of America
The RF power density limits according to FCC directive CFR 47 Part 2.109, are shown in the table below:
The general equations for Occupational level:
For 100 to 300 MHz, RF power density = 10 W/m
2
, and
For 300 to 400 MHz, RF power density = f /30 W/m
2
where, f = frequency in MHz.
The general equations for General population level:
For 100 to 300 MHz, RF power density = 2.0 W/m
2
and,
for 300 to 400 MHz, RFR power density = f /150 W/m
2
where, f = frequency in MHz.
Example
The safe distance from the antenna can be predicted using the equation:
where,
R = distance to centre of radiation in metres (m)
P = average power input to antenna in Watts (example, 100 W carrier with 95% modulation = 145 W)
G = antenna gain as a ratio (example, 2 dB = 10
2/10
= 1.585)
S = power density in W/m
2
.
Based on this formula and using a 2 dBi antenna, frequency of 118.000 MHz and a measured carrier power of
1
00 W, for occupational workers:
 The predicted safe distance from the centre of the radiation would be approximately 1.4 m.
For persons not classed as occupational workers, and including the general public:
The minimum safe distance would be 3.1 m.
Note:
Safe distances are rounded up to the nearest 0.1 m.
Frequency MHz
Occupational level
W/m
2
General population level
W/m
2
112.000 - 300.000 10.0 2.00
399.975 13.34 1.57
R =
PG
4S
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