| ratio, generally expressed in decibels, of the radiation intensity produced in a given direction by an antenna to the radiation intensity that would be obtained if the power accepted by the antenna were radiated equally in all directions
Note 1 to entry: If no direction is specified, the direction of maximum radiation intensity from the given antenna is implied.
Note 2 to entry: When the absolute gain is expressed in decibels, the notation dBi is recommended by the International Telecommunication Union as a unit symbol.
Note 3 to entry: The radiation intensity from an antenna in a given direction is the power radiated per unit solid angle.
Note 4 to entry: If the antenna is lossless its absolute gain is equal to its directivity in the same direction.