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**

**Formula**

Total radiated power in dBm is given by

**TRP _{dBm} = PTx_{dBm} + η_{dB} **

where,

**PTx**is the power output from the transmitter_{dBm}**η**is the antenna efficiency_{dB}

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

**TRP _{dBm} = EIRP_{dBm} – D**

_{dB}

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**.