Effective radiated power
Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity (signal strength, or power flux density, expressed as power per area) as the actual source antenna at a distant receiver located in the direction of the antenna's strongest beam (main lobe).