Different methods of PO analysis in a dual reflector antenna with a shaped main reflector

Abstract

The shaped reflector has emerged as a vital technology in the field of satellite antennas. The dual offset Gregorian geometry considered, using an ellipsoidal subreflector fed by a spherical source feed, is shown. In a Cassegrainian system, a hyperboloid is used as the subreflector. By choosing an optimum tilt angle between the main reflector and the subreflector axes, the cross-polarization in a dual offset reflector can be minimized. Thus, by shaping the main reflector a shaped beam with superior cross-polar performance can be realized. The surface profile of the shaped reflector is synthesized using an accurate analysis embedded inside an optimization. This accurate analysis is usually based on physical optics (PO). Ideally a dual reflector analysis using PO on both the subreflector and the main reflector is necessary to synthesize the main reflector shape. This can be very time consuming and unnecessary especially if only the main reflector shape is synthesized. Two other simplified techniques which can be used more efficiently during the main reflector synthesis, are presented. A brief overview of the different analysis techniques are also presented.