Effective Isotropic Radiated Power (EIRP)

What is this formula?

Effective Isotropic Radiated Power (EIRP) represents the power that an ideal isotropic antenna would need to radiate to produce the same maximum power density as a real transmitting antenna. It combines transmitter power and antenna gain into a single parameter.

When to use it

Use this formula when performing link budget calculations, designing wireless systems, evaluating regulatory compliance, planning satellite communications, or comparing transmitting systems.

Example

A transmitter delivers 50 W to an antenna with a gain of 20.

Formula:

EIRP = Pt*Gt

Substitution:

EIRP = 50*20

Result:

EIRP = 1000 W

The equivalent isotropic radiated power is 1000 W.

Applications

Satellite communications, cellular networks, microwave links, Wi-Fi systems, radio broadcasting, regulatory analysis, and wireless system design.

Note

This formula assumes that antenna gain is expressed as a linear ratio. When antenna gain is specified in dBi, EIRP calculations are normally performed in decibels using EIRPdBW = PtdBW + GtdBi. Real systems may also include cable, connector, and feeder losses that should be incorporated into a complete EIRP calculation.