The measure of effectiveness of a directional antenna as compared to an isotropic radiator, maximum value is called antenna gain by convention.

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 radiati [..]

The ability of an antenna to focus in on signals from a specific direction.

An antenna focuses the radio waves in a certain direction. Usually, this is called the main direction. Because of that, in other directions less energy wil be emitted. The gain of an antenna, in a giv [..]

 - An antenna's transmission power, provided as a ratio of its output (send) signal strength to its input (receive) signal strength, normally expressed in dBi. The higher the dBi, the stronger the antenna.

the ratio of the power produced by an antenna as compared to the power produced by a hypothetical lossless isotropic antenna, usually expressed in decibels-isotropic (dBi). Compare with antenna effici [..]

refers to any increase or decrease in the strength of a wireless RF radio frequency signal when considering external antenna equipment. Gain is typically measured in terms of decibels (dB) or a number of times of magnification.

In technical terms, the gain is 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 measure of effectiveness of a directional antenna as compared to an isotropic radiator, maximum value is called antenna gain by convention.

See gain.

A measure of the output of an antenna compared to a standard antenna using the same frequency. Read more on Antenna Gain.