Multibeam antenna for 30/20 GHz advanced communications satellite using offset shaped, dual reflector surfaces

Progress in the Antenna Technology Study being performed by NASA to characterize an antenna system with a scaning beam with a half-power beam diameter of around 0.3 deg and a minimum width over which the sidelobes stay below the -30 dB level is reported. Continuous U.S. (CONUS) coverage is desired by the satellite antenna system, with 10-20 fixed beams for trunk coverage and a rapidly scanned narrow beam for customer premises. The design specifies 24 beamwidths from east to west and 10 beamwidths from south to north. Reflector parameters have been identified to optimally focus all beams from a planar feed array. An example of coverage expected with the design demonstrates optimized beams for Seattle, Oklahoma City, and Miami, with -3 dB contours in circles 0,25 deg in diameter and a peak directivity of 55 dB. Experimental work was scheduled for 1983.