Antenna effective area

In telecommunication, antenna effective area is the functionally equivalent area from which an antenna directed toward the source of the received signal gathers or absorbs the energy of an incident electromagnetic wave.

Note 1: Antenna effective area is usually expressed in square meters.

Note 2: In the case of parabolic and horn-parabolic antennas, the antenna effective area is about 0.35 to 0.55 of the geometric area of the antenna aperture.

Source: from Federal Standard 1037C