Contoured-beam horn-reflector antenna designed by plane wave synthesis

A satellite reflector antenna having a main beam and subbeam often enables us to illuminate the service area effectively. We present a new reflector-shaping design method for a contoured-beam antenna producing such beams by means of wave front synthesis. We determine the shape of the wave front associated with the main beam and then superimpose a plane wave associated with the subbeam onto it on the antenna aperture. The reflector is shaped to attain such a combined wave front by the optical path law. This method is applied to shape a 30/20-GHz horn-reflector antenna, whose diameter is 950 mm and flare angle (full) is 40°, and the fundamental properties of this method are investigated. It is found that this method is effective for producing a contoured-beam composed of a main beam and a subbeam. As an application, we design a contoured-beam horn-reflector antenna illuminating Japanese territory by means of the plane wave synthesis.