Cobham SATCOM
Marine Systems, Sea Tel Products
4030 Nelson Ave., Concord
California, 94520 USA
T: +1 (925) 798-7979
F: +1 (925) 288-1420
Maximum Safe RF Exposure Power Levels
Antenna Antenna Typical Peak Power Nominal Power Max Safe Peak Power Nominal Power
Diameter Area BUC Power Density Density BUC Power Density Density
Meters cm^2 Watts mW/cm^2 mW/cm^2 Watts mW/cm^2 mW/cm^2
0.6 2,827 5 1.8 0.1 25 8.8 0.6
1 7,854 8 1.0 0.1 75 9.5 0.6
1.2 11,310 25 2.2 0.1 100 8.8 0.6
1.5 17,671 25 1.4 0.1 150 8.5 0.5
1.8 25,447 25 1.0 0.1 250 9.8 0.6
2 31,416 50 1.6 0.1 300 9.5 0.6
2.4 45,239 75 1.7 0.1 450 9.9 0.6
3.6 101,788 100 1.0 0.1 1000 9.8 0.6
8797 (2.0) 30,500 50 1.6 0.1 300 9.8 0.6
9797 (2.4) 42,450 100 2.4 0.1 400 9.4 0.6
Notes:
The ‘Peak Power Density’ values shown above assume a 100 percent duty cycle modulation of the RF power amplifier
(BUC) at its maximum possible output power. No satellite network is ever operated at this extreme level. The ‘Nominal
Power Density’ values shown above, represent operation with a 10 percent duty cycle modulation and a 2 dB power
backoff (0.1 x 0.63). These are realistic values for operation within a network that accommodates multiple users.
The FCC has defined, in document 'OET Bulletin 65', the maximum safe exposure level for controlled environments to be
5 mW/cm^2 and the maximum safe exposure level for uncontrolled environments to be 1 mW/cm^2. Clearly, the ‘Typical
BUC Power’ installations meet this requirement with a safety margin of 10. Furthermore, any system equipped with a
BUC or RF power amplifier equal to or less than the 'Max Safe BUC Power' stated above, is guaranteed to be safe
outside the confines of the radome walls.
By contrast, an analog cellular telephone, with a peak power output of 2 Watts produces a power density, averaged over
the area of your head of 20 mW/cm^2. Localized power densities, i.e. next to your ear, can approach 200 mW/cm^2.
Digital cellular telephones typically operate with a duty cycle between 1 and 5 percent making the averaged power density
equal to or slightly below the FCC defined safe level. Compared to the table values above, a cellular telephone produces
between 10 and 100 times the RF exposure level of a typical Sea Tel satellite terminal.
Peter G. Blaney
Chief Engineer, Sea Tel Products
Cobham SATCOM, Marine Systems
Doc: 99-130856-A
Sea Tel, Inc., doin
business as Cobham SATCOM
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