Design and Optimization of Surface-Wave Enhanced Reflecting Metasurfaces Featuring Beamforming and Polarization Control

Electromagnetic metasurfaces (MTSs) are typically modeled as passive, lossless, and purely reactive homogenized impedance sheets on dielectric substrates. In this paper, we present an overview of designing reflecting MTSs using the method of moments (MoM) with gradient-based optimization. The proposed MTSs consist of printed metallic patterns placed over a grounded dielectric slab, with the patterns modeled by impedance sheets, and the impedance values optimized through gradient-descent to achieve specific far-field (FF) power patterns or beamforming objectives. This beamforming/beamshaping capability is enabled utilizing auxiliary surface waves, without the need of any explicit gain or loss. Full-wave simulations of realistic copper structures are presented to validate the proposed design procedure, with measurements preformed for an one dimensional (1D) MTS. An example of a 2D MTS featuring polarization control is also presented.