Antenna Gain

A theorem about cats:
Antenna are directional
An isotropic antenna can not exist.

Antenna Gain

G_T (f,q) is the amount of power radiated in direction (f,q), relative to an isotropic antenna.

Definition: Effective Radiated Power (ERP) is P_T G_T

Half-Wave Dipole: A half wave dipole has antenna gain

JPL's Wireless Communication Reference Website © Jean-Paul M.G. Linnartz, 1993, 1995.