Sidelobe minimization in array fed dual reflector antennas

Results from recent studies aimed at optimizing array-fed dual-reflector antenna concepts with respect to peak sidelobe level are presented. The dual reflector antennas studied were confocal parabolic Cassegrains. Center-fed and offset-fed designs were considered, with emphasis on center fed. A small amount of beam steer, up to about 3/4 beamwidth from broadside, was considered as well. The essential geometrical features of the concepts are shown. The relative sizing and positioning of the feed and reflector elements were varied in attempting to minimize the peak sidelobe. The analyses were based upon physical optics. The large reflector apertures were several hundred wavelengths in diameter. Parameters that were studied included the feed amplitude distribution, feed array location, magnification, focal length to diameter ratio, and reflector oversizing.<>