A Confocal Ellipsoidal Reflector System for Millimeter-Wave Applications

In this paper, an axisymmetric dual reflector system, called the confocal ellipsoidal structure, is proposed for millimeter-wave applications. It is shown that by using a deliberate modification of the secondary reflector (subreflector) profile in the standard axisymmetric Gregorian structure, the blockage can be reduced considerably. This modification is performed by applying simultaneous displacement and tilting techniques on the subreflector. The proposed confocal ellipsoidal structure can be applied to both communication antennas and quasi-optical imaging systems by adopting a proper main reflector profile. The performance of the proposed structure in each of the mentioned applications is investigated by numerical simulations. Specifically, the reduction of the blockage and imaging performance of the confocal ellipsoidal structure is studied in various scenarios. Based on the simulations, acceptable results are obtained in the focusing and scanning performance. Having a simple structure and a noticeable performance, the proposed structure is promising for millimeter-wave standoff imaging and communication.