Reconfigurable Polarization Converter Using Liquid Metal Based Metasurface

Abstract

A multifunctional reconfigurable metasurface based on liquid metal injection is presented. The reflective flexible material metasurface formed by two switchable microfluidic layers&#x2014; the top layer comprising an array of meandered half-rings and the lower layer, straight meander lines&#x2014;can be reconfigured into four states. The proposed metasurface becomes a reflector with emptied channels, whereas it exhibits linear-to-circular polarization conversion (or linear-to-cross-polarization conversion) properties when the top (or bottom) layer is filled with a liquid metal alloy. Upon normal excitation of linearly u/v-polarized waves and activation of the bottom layer, the metasurface reflects cross v/u-polarized waves in the frequencies from 9.83 to 17.42 GHz (53&#x0025; bandwidth) with a polarization conversion ratio (PCR) of at least 90&#x0025;. On the other hand, the metasurface operates as a linear-to-circular polarizer (for u/v-polarized waves) over 8.97&#x2013;11.30 GHz (23&#x0025; bandwidth), reflecting left- or right-hand circularly polarized waves. To verify the polarization conversion performance, a <inline-formula> <tex-math notation="LaTeX">$25\times 25$ </tex-math></inline-formula> element metasurface array is fabricated and measured. The experimental results confirm the simulation results over the 8&#x2013;12 GHz test band. The compactness, structural flexibility, and multifunctionality of the proposed metasurface make it a suitable candidate for modern integrated antenna array systems.