Compact Low-Profile Aperture Antenna with Integrated Diplexer

An efficient, low-profile, lightweight fixed-beam (constant angle of departure) aperture antenna. The aperture antenna includes an array of horn radiators coupled to a waveguide diplexer by means of a stripline distribution network. The stripline distribution network is embedded in a printed wiring board (PWB), which PWB is sandwiched between a radiator plate (incorporating the horn radiators) and a diplexer plate. The aperture antenna may further include a backside ground plane made of metal. The diplexer plate and backside cover plate are configured to form the waveguide diplexer. Each horn radiator has a respective circular opening at one end adjacent to the PWB. The diplexer plate includes an array of circular waveguide backshorts which are congruent and respectively aligned with the circular openings of the horn radiators. The radiator plate further includes a rectangular waveguide backshort which is congruent and aligned with a rectangular port of the diplexer plate.