A Dual Band Transmittive-type Linear to Circular Polarization Converter using Single Layer Metasurface

This manuscript presents a novel metasurface (MS) based structure which can convert a transmittive-type linearly polarized incident electromagnetic (EM) wave into circularly polarized one in two distinct frequency bands incorporating a single layer of dielectric. The unit cell of the MS comprises six diagonally arranged metallic small square patches enclosed by a metallic square ring at the edge. The proposed structure has been designed on a $\lambda / 32$ thick dielectric substrate along with the periodicity of $\lambda / 5$ where $\lambda$ is free space wavelength with respect to the center frequency of the lower conversion band. The transmitted EM wave is circularly polarized (CP) in nature in C and Ku bands as the axial ratio is below 3 dB at 5.34 GHz to 6.8 $\mathbf{G H z}$ and 13.3 GHz to 16.01 GHz, being centered at 6 GHz and 14.5 GHz respectively. The chirality and surface current have been studied to confirm that the transmitted waves are respectively left-handed CP and right-handed $C P$ in C and $K u$ bands. The proposed structure can find potential applications towards space and satellite communications.

I. Introduction

A metasurface (MS) is a subwavelength ultra-thin two dimensional periodic structure which can be designed to alter the characteristics of the electromagnetic (EM) wave [1]. The surface of the structure manifests the artificial electrical parameters [2] extending its application in multiple aspects such as absorbers, antennas, filters etc. [3]–[5].