Cassegrain reflector sidelobe reduction study

Abstract : This report presents the results of a 4-month study to reduce the sidelobe levels of a 38 GHz, 2 ft diameter Cassegrain reflector. Both partial and full circumferential shrouds were added to the main reflector. Various shielding techniques to reduce the horn and subreflector radiation characteristics were evaluated. Measured primary patterns for the various horn-subreflector combinations were used to compute the secondary reflector patterns to evaluate the sidelobe improvement. The computed patterns were compared with measured results. Keywords include: Cassegrain reflectors, Space frame radome, Horn-subreflector feed patterns, and Tunnel reflector antennas.