Design of the axially displaced monopulse cassegrain antenna with low profile at W band

This paper presents an axially displaced monopulse Cassegrain antenna with low profile at W band. The antenna configuration consists of a hyperboloid as the subreflector, a combination of series of paraboloids with different focal length as the main reflector to keep low profile, and is fed by five horns. Closed-form design equations are derived using the principles of geometrical optics. CST is implemented to further analyze this antenna. Simulation results show that over the operation bandwidth, in the sum patterns, the gains are within the range of 40.0-40.4 dBi, the sidelobe levels are less than -19 dB, and the null-depths in the difference patterns are below -35 dB. This antenna presents an excellent candidate for radar and communication system at W band.