ANTENNA GAIN
Weather
The measure of effectiveness of a directional antenna as compared to an isotropic radiator, maximum value is called antenna gain by convention.
Telecommunications
The ratio of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance. Note 1: Antenna gain is usually expressed in dB. Note 2: Unless otherwise specified, the gain refers to the direction of maximum radiation. The gain may be considered for a specified polarization. Depending on the choice of the reference antenna, a distinction is made between:
- absolute or isotropic gain (Gi), when the reference antenna is an isotropic antenna isolated in space;
- gain relative to a half-wave dipole (Gd) when the reference antenna is a half-wave dipole isolated in space and with an equatorial plane that contains the given direction;
- gain relative to a short vertical antenna (Gr), when the reference antenna is a linear conductor, much shorter than one quarter of the wavelength, normal to the surface of a perfectly conducting plane which contains the given direction. [RR] Synonyms gain of an antenna, power gain of an antenna.