Design of a W-Band Full-Polarization Monopulse Cassegrain Antenna

This letter introduces a W-band full-polarization monopulse antenna based on the sequential rotate polarization theory. The proposed antenna consists of a main reflector, a subreflector, and a sequential rotate polarization feed to realize full-polarization monopulse angle measurement. The circular polarization monopulse patterns are simulated and measured by using special amplitude and phase setting. The measured results are in good agreement with the simulated ones. The SUM beam gain of the proposed antenna is 36.1 dBi by eliminating the loss of W-band comparator, cross-polarization level is better than -23 dB, and 3-dB beamwidth is 1.65 degrees. The first sidelobe level is under -17 dB. The gain ratio between the SUM and DIFF beams is 5.5 dB. The proposed antenna is a good candidate for W-band full-polarization monopulse detector.