Analysis of parabolic reflectarray in dual-reflector configuration

A technique is presented in this paper for the analysis of a dual-reflectarray antenna configuration comprising a parabolic reflectarray as main reflector. The analysis is based on a modular technique that comprises the following steps: First, the near field radiated by the feed-horn is computed on each sub-reflectarray elements. Second, each element on the sub-reflectarray is analysed by the Method of Moments (MoM) assuming local periodicity and considering the real values of the incidence angle. Third, each element on the main reflectarray is analysed in a similar way by MoM but considering as incident field the field radiated by the subreflectarray. In this case, the curvature of the surface is taken into account for the calculation of the incidence angle. Finally, the co- and cross-polar radiation patters of the antenna are obtained from the field reflected on the elements of the main reflectarray. The technique has been applied to analyse a single offset parabolic reflectarray designed previously to produce a South American coverage. The co-polar and cross-polar radiation patterns are shown, showing that the contoured beam is in close agreement with the predictions previously reported.