Ultra-thin reflecting polarization beam splitter under spherical waves’ illumination by using single-layered anisotropic metasurface

Abstract

Planar focusing metasurface is capable of converting spherical waves into plane waves, while gradient phase distribution on metasurface contributes to anomalous reflection. By combining the double cases, we propose a new route of both gain enhancement and anomalous reflection. By using a compact ultra-thin anisotropic element, we design a polarization beam splitter under spherical waves’ illumination. With different phase gradients for x/y-polarized waves, the anisotropic metasurface has function of gain enhancement of 12.4 dB on average and reflecting x/y-polarized waves in −x/+y direction with the same reflected angel of 33° at the operating frequency of 15 GHz. For verification of simulation results, the metasurface sample with size of 102 × 102 mm2 and cells of 17 × 17 is fabricated and measured. Experimental results are in excellent agreement with the simulated ones, in which the high isolation of 30 dB at 15 GHz between x- and y-polarized waves is obtained. Due to the great performance in beam steering and thickness reduction, our design provides a promising approach of beam splitting, steering and gain enhancement in microwave region.