Multilayer Reflectionless Wide-Angle Anomalous Refractors Based on Surface Field Optimization

In this work, we discuss the application of a numerically efficient tool based on the optimization of surface field harmonics for the design of reflectionless multilayer wide-angle anomalous refractors. In the proposed design approach, a certain number of evanescent Floquet modes are introduced through an optimization procedure aiming at minimizing the real part of the sheets surface impedance. Unlike the standard three-layer design, the one presented here offers the flexibility to choose an arbitrary number of layers as an input parameter during the design phase, providing an additional degree of freedom to explore novel solutions. Here, we compare the performance of three-layer and four-layer designs for achieving a -20° to +40° anomalous refraction. The optimized four-layer design exhibits spatially bounded admittance profiles, resulting in more effective anomalous refraction compared to the three-layer counterpart, which features asymptotes. The results are obtained using an in-house full wave analysis tool.