Tracking antenna with a partially corrugated reflector

Tracking antennas using the monopulse technique to determine the target direction have been in service for many years. It is well known that cross-polarisation in the difference channel on boresight will lead to a tracking error for incoming signals that do not have perfect polarisation purity. This is precisely the problem that afflicts an offset reflector with monopulse feed. This paper reports upon a novel solution to the problem based upon corrugating a portion of the reflector surface such that the antenna cross-polar signal is reduced, or even cancelled on boresight