In telecommunication, a reflective array antenna is an antenna, such as a billboard antenna, in which the driven elements are situated at a predetermined distance from a surface designed to reflect the signal in a desired direction.

Note: Reflective array antennas (a) usually have many driven elements working in conjunction with an electrically large reflecting surface to produce a unidirectional beam, (b) may be used to increase antenna gain, i.e., reduce radiation in unwanted directions, and (c) may contain parasitic elements as well as driven elements.

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