A 2D Inverse Design Method for Planar Printed Circuit-type Antenna Superstrate to Achieve Stable Shaped Beam Pattern

A 2D subspace optimization-based inverse design method (SO-IDM) is proposed for planar multilayer printed circuit-type antenna superstrate to achieve a desired stable shaped beam pattern, which results in the final antenna with high aperture efficiency, lightweight, low profile, and ease of fabrication. The method first designs the total electric field values in the far-zone based on the desired radiation patterns at the frequencies of interest. Then, the scattered fields from the superstrate are obtained by the incident fields generated by the source antenna and the designed total fields. Thereafter, based on inverse scattering theory, the metallic structures of the superstrate can be reconstructed via the subspace optimization method, where the multilayer substrates are considered as a part of background. To further improve the compactness, a layer impact factor is introduced to minimize the number of the layers, reducing the use of unnecessary structures. In order to validate the effectiveness and practical applicability of the proposed SO-IDM, a stable flat-topped radiation pattern with low ripple level was considered. Compared with the traditional forward and inverse design methods for dielectric lenses, the proposed SO-IDM can inverse design planar printed circuit-type superstrate with good radiation but smaller aperture, lighter weight, and lower profile, which fully highlights its advantages in engineering applications.