Effective XPD and XPI Optimization in Reflectarrays for Satellite Missions

Abstract

Crosspolar requirements for space-borne antennas are very stringent. In some missions such as Direct Broadcast Satellite (DBS) these requirements are specified in terms of crosspolar discrimination (XPD) and crosspolar isolation (XPI), usually with values higher than 33dB. In this regard, the most common approach for crosspolar optimization for reflectarray antennas is to set up a crosspolar template with certain values, improving the XPD and XPI indirectly. In this work, it is proposed to directly optimize the XPD and XPI in reflectarray antennas with the aim of obtaining better results than the usual crosspolar optimization. For this purpose, the generalized Intersection Approach is employed, for which the forward projection is improved to include XPD and XPI templates. Three optimization strategies are compared: optimizing the crosspolar pattern, the XPD and the XPI. The direct optimization of the XPD and XPI achieves better results in less iterations than the common approach of the crosspolar pattern optimization while keeping the copolar pattern within requirements.