Reconfigurable Polarization Converter Using Liquid Metal Based Metasurface

A multifunctional reconfigurable metasurface based on liquid metal injection is presented. The reflective flexible material metasurface formed by two switchable microfluidic layers— the top layer comprising an array of meandered half-rings and the lower layer, straight meander lines—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% bandwidth) with a polarization conversion ratio (PCR) of at least 90%. On the other hand, the metasurface operates as a linear-to-circular polarizer (for u/v-polarized waves) over 8.97–11.30 GHz (23% bandwidth), reflecting left- or right-hand circularly polarized waves. To verify the polarization conversion performance, a $25\times 25$ element metasurface array is fabricated and measured. The experimental results confirm the simulation results over the 8–12 GHz test band. The compactness, structural flexibility, and multifunctionality of the proposed metasurface make it a suitable candidate for modern integrated antenna array systems.