Design and optimization of a multi-resonant reflectarray element

The design and analysis of reflectarray antennas (RAs) often applies the local periodic assumption, whereby all elements are assumed to be identical. However, elements in a RA design differ geometrically from their neighbors, which can result in undesired perturbations of the reflectarray antenna pattern. In this paper, we explore the use of parasitically loaded elements in the reflectarray unit cell to compensate for this effect. An optimization scheme is integrated in the design process to improve the antenna pattern. As a proof of concept, the optimization of a plane-wave re-direction surface is presented.