Billboard antenna

In telecommunication, a billboard antenna is an array of parallel dipole antennas with flat reflectors, usually positioned in a line or plane.

Note 1: The spacing and dimensions of the dipoles depend on the wavelength.

Note 2: The main lobe of a fixed billboard antenna may, within limits, be steered by appropriate phasing of the respective signals to individual elements of the array. Synonym broadside antenna.

Source: from Federal Standard 1037C