Crosspolar Optimization in Reflectarray Antennas for DBS missions

Abstract

Current satellite applications for communications specify very tight cross-polarization values, usually with parameters such as the crosspolar discrimination (XPD) larger than 33 dB. To obtain these values, optimization of the cross-polarization performance has to be performed. The most common approach is to minimize the crosspolar component of the radiation pattern with regard to the copolar pattern in a subset of the visible region, corresponding to the coverage area. Nevertheless, this type of optimization provides suboptimal results since the figure of merit for cross-polarization performance (e.g. the XPD) is only optimized indirectly. Thus, in this work we propose to directly optimize the figure of merit to considerably improve the polarization purity of reflectarrays for satellite missions. For that purpose, the generalized intersection approach algorithm is employed in a very large reflectarray for a shaped beam application with European footprint. We show that directly optimizing the cross-polarization figure of merit provides better results than the usual approach of minimizing the crosspolar far field.