Satellite phased arrays - Use of imaging reflectors with spatial filtering in the focal plane to reduce grating lobes

The imaging reflector arrangement described in this paper forms a very compact antenna design suitable for generating a scanning fan beam for a 12/14-GHz synchronous satellite communicating with points located in the continental United States. A magnified image of a small array is obtained using a Gregorian arrangement of two paraboloids. A filter, placed in the focal plane of the main reflector, eliminates undesirable field components due to the grating lobes of the small array. Because of the filter, the illumination over the main aperture is a smoothed version of the array illumination. Thus, grating lobes are greatly reduced. By properly adjusting the excitation of the various array elements, an antenna with very low side lobes is obtained