Phased array

In telecommunication, a phased array is a group of antennass in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions. This design is used in radar, and is generalized in interferometric radio antennas (usually in radio telescopes).

The relative amplitudes of--and constructive and destructive interference effects among--the signals radiated by the individual antennas determine the effective radiation pattern of the array. A phased array may be used to point a fixed radiation pattern, or to scan rapidly in azimuth or elevation.

Source: from Federal Standard 1037C and from MIL-STD-188