Development of a novel 38.5 GHz planar Cassegrain antenna

The design and results of a novel 38.5 GHz Cassegrain antenna using printed-circuit planar reflectors are presented. This antenna contains a feed patch antenna, a main reflector for twisting and focusing the incident wave, and a sub-reflector for polarization selection. The sub-reflector is made of a PCB printed with a dense metal grid, which is transparent to one polarization but would reflect the other polarization. The main reflector includes hundreds of microstrip antennas which are used to produce twisted reradiation fields and provide phase compensation. This type of antenna has a low-profile configuration and is suitable for mechanical beam scanning.