An arrangement of radiating or receiving elements so spaced and connected to produce directional effects. Very great directivity and consequently large antenna gain can be produced by suitable design. An array of elements along a horizontal line is referred to either as a broadside array or endfire array depending on whether the directivity is in the horizontal plane at right angles to or along the line of the array, respectively. Arrays are commonly designed to have both horizontal and vertical directivity. The horizontal directivity is determined by the horizontal arrangement of antenna elements while the vertical directivity is dependent on the number of elements arranged in tiers (or stacks) one above the other.

The performance of an antenna array is indicated by the antenna pattern of the system. The direction of maximum transmission or reception is given by the major lobe of the antenna pattern (see also steerable antenna).