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.