Multi-band ring focus antenna system with co-located main reflectors

A compact multi-band ring-focus antenna system. The antenna system includes a first and a second main reflector each having a shaped surface of revolution about a common boresight axis of the antenna. A first backfire type RF feed system is provided for feeding the first main reflector on a first frequency band. A second RF feed coaxial with the first RF feed is provided for feeding the second main reflector on a second frequency band spectrally offset from the first frequency band. Further a portion of the second RF feed passes through a first sub-reflectors of the backfire feed. The second RF feed is terminated a distance from the first sub-reflector to illuminate a second sub-reflector.