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 |