Design of diffractive Cassegrain antenna at W band

In this paper, a diffractive Cassegrain antenna for the monopulse radar at W band is designed. The main-reflector of the antenna is divided into several rings, and the surface in each ring is a part of a parabolic reflector with different focal length. The antenna has a gain of 37.6dB and the first sidelobe level is about −18.9dB. The thickness profile of the antenna is less than 10mm on the edge and 30mm in the center. Its radiation performances are comparable with the traditional Cassegrain antenna, but it has a much lower thickness profile.