Comparison of Different Approaches in Reflectarray Synthesis Based on Intersection Approach

Abstract

This work presents a comparison between a number of numerical techniques for the copolar synthesis of reflectarray antennas. These techniques are based on the generalized intersection approach. The classical phase-only synthesis (POS) is considered using different methodologies to compute the gradient: the analytical approach by exactly calculating the derivative and two numerical methods based on finite differences, one using the FFT and another the technique of differential contributions (DFC). In addition, a direct layout optimization (DLO) for copolar synthesis is also considered. In order to make the DLO efficient, a surrogate model of the unit cell is employed. A computing time study is presented, showing that for copolar only synthesis at a single frequency, the POS technique using DFC has superior performance. Finally, a large reflectarray with European footprint for satellite broadcasting is synthesized, comparing the results obtained with all techniques.