The average power at the antenna:
The antenna gain in dBi:
Enter 2.2 for dipoles; add 2.2 for antennas rated in dBd
The distance to the area of interest:
From the centre of the antenna, in feet
The frequency of operation:
Monday, January 2, 2012
Using the RF Amateur Radio RF Safety Calculator
DX-Zone has posted an Amateur Radio RF Safety Calculator for hams to use to make it easy to comply with the RF safety requirements of the FCC. See link at the bottom of this posting.
Calculate Radio Frequency Power Density
B – This information is usually available from the antenna manufacture for commercial antennas. For home brew (ham speak for home made) antennas, you may have to do some research to get an estimate of what a similar antenna’s gain might be.
C – This is the closest point that a person might come to the antenna during transmitter operation. That means if someone 6 feet tall is standing under an antenna whose center is 18 feet above the ground, that person is 12 feet from the antenna. This includes people inside a building where the antenna is mounted.
D – If the antenna is a multiband you must run the calculation for each band. Use a frequency near the center of each band.
This calculator is the easiest one I have found to use. There is a lot of good information on RF Safety on the DX-Zone website. Once you are on DX-Zone website run a search for RF Safety using their site search.
RF Amateur Radio RF Safety Calculator http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=11352