Total radiated power (TRP) is the total power radiated by an antenna. It is a function of the output power from the transmitter and the antenna efficiency. As the antenna efficiency decreases, the amount of radiated power decreases. The most efficient antenna will radiate all the power that’s provided at its input.

Effective Isotropic Radiated Power (EIRP) is the power that would have to be radiated by an isotropic antenna to provide the same signal level as the actual source antenna in the direction of the antenna’s strongest beam.

EIRP to TRP Calculator


Total radiated power in dBm is given by

TRPdBm = PTxdBm + ηdB


  • PTxdBm is the power output from the transmitter
  • ηdB is the antenna efficiency

The antenna efficiency in linear terms is η = G/D where

  • G is the antenna gain
  • D is the directivity

The Total radiated power is then given by

TRPdBm = EIRPdBm – DdB

EIRP is always greater than TRP.

Example Calculation

The directivity of an Omni Directional antenna is 0 dB. For this antenna the Total Radiated Power is equal to the Effective Isotropic Radiated Power.

For EIRP = 10 dBm and D = 5 dB, TRP = 5 dBm.