EIRP
EIRP is the actual power of the signal that comes from the antenna, measured
in Decibel Milliwatts (dBm). (0 dBm equals 1 milliwatt of power.) EIRP is
calculated by taking the transmitter power, subtracting the amount of signal
lost traversing the cable between the transmitter and antenna, and adding the
antenna’s gain. This can be expressed:
EIRP = (power – cable loss) + antenna gain.
Different countries have different rules about the amount of EIRP allowed.
For instance, the maximum in the United States is 36 dBm. To minimize
signal loss, use the shortest low-loss cable possible. Wider cables conserve
more signal but are also more expensive.