Effective Isotropic Radiated Power (EIRP)
EIRP is the power a transmitter would need to radiate from an isotropic antenna to match the peak signal of its actual antenna; ERP is the same measure relative to a dipole.
What is Effective Isotropic Radiated Power (EIRP)?
EIRP equals transmitter power minus losses plus antenna gain in dBi. ERP is 2.15 dB lower than EIRP. Licences usually cap EIRP or ERP.