A dual-reflector optical feed for wide-band phased arrays

This paper contains a description of the fundamental performance characteristics of a new space feed suitable for wideband operation of phased-array antennas. A unique aspect of this feed is the combination of an active time-delayed small source array and a confocal passive two-reflector system in an offset Gregorian configuration to provide wide-band compensation to a scanning phased array antenna contaning only radiators and phase shifters. A two-dimensional model is analyzed using the plane wave spectrum representation of the near field. Calculations for bandwidths of up to 20 percent of center frequency are given. The good electrical performance of the feed as a function of bandwidth and scan angle establishes this system as an attractive candidate in space feed applications and as a tradeoff competitor or alternative to the conventional corporate feed.