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Table: RF Power Density

RF Power Density vs Distance

The RF power density at any distance from a transmitter that is radiating RF power will depend upon the antenna gain, power into the antenna, and the distance from the antenna.  The table below illustrates haw fast the RF power power density drops off given certain distances from the radiating antenna and the power into the antenna.

11 meters from a 125 watt transmitter is about the same RF power density as 1 meter from a 2 watt transmitter.

 

Power (dBm) Power (Watts) Antenna Gain (dBi) Antenna Gain Factor Distance (meters) PSD(W/m2)
20 0.10 0 1 0.1 0.796
20 0.10 0 1 0.5 0.032
20 0.10 0 1 1 0.008
20 0.10 0 1 3 0.001
20 0.10 0 1 10 0.000
30 1.00 0 1 0.1 7.962
30 1.00 0 1 0.5 0.318
30 1.00 0 1 1 0.080
30 1.00 0 1 3 0.009
30 1.00 0 1 10 0.001
33 2.00 0 1 0.1 15.886
33 2.00 0 1 0.5 0.635
33 2.00 0 1 1 0.159
33 2.00 0 1 3 0.018
33 2.00 0 1 10 0.002
36 3.98 0 1 0.1 31.696
36 3.98 0 1 0.5 1.268
36 3.98 0 1 1 0.317
36 3.98 0 1 3 0.035
36 3.98 0 1 10 0.003
42 15.85 0 1 0.1 126.186
42 15.85 0 1 0.5 5.047
42 15.85 0 1 1 1.262
42 15.85 0 1 3 0.140
42 15.85 0 1 10 0.013
51 125.89 0 1 0.1 1002.329
51 125.89 0 1 0.5 40.093
51 125.89 0 1 1 10.023
51 125.89 0 1 3 1.114
51 125.89 0 1 10 0.100
54 251.19 0 1 0.1 1999.910
54 251.19 0 1 0.5 79.996
54 251.19 0 1 1 19.999
54 251.19 0 1 3 2.222
54 251.19 0 1 11 0.165

Filed under: Engineering | Posted on December 26th, 2012 by John Sonnenberg

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