Circular Polarization Conversion Using Dual Frequency Selective Surfaces for Full-Duplex Satellite Communications

Abstract

This article proposes an approach to circular polarization conversion using two anisotropic frequency selective surfaces in a frequency-duplex system. We focus on validating the proposed conversion topology from H-polarization to left-hand circular polarization in the forward channel at f(1) , and from right-hand circular polarization to V-polarization in the backward channel at f(2), to enable full-duplex satellite communications. The multiconductor transmission line model is employed to characterize the properties of each unit cell and to express the required scattering parameters for each surface at frequencies f(1) and f(2) . The obtained scattering parameters are then realized using a cascade of two frequency selective surfaces. The first surface features a diagonal strip to convert the incident H-polarized field into its perpendicular V-polarized field at f(1) . The second surface, employing a dual-split-ring structure, functions as an anisotropic layer to transform the perpendicular component into circular polarization. Similarly, at f(2) , the reverse channel converts an incident right-hand circularly-polarized field into an V-polarized output field. The proposed approach has been validated in the X-band and tested for polarization transformation performance in a full-anechoic chamber. The experimental results demonstrate that each surface and the entire dual-frequency selective surface system effectively operate as a frequency-duplexer which enables simulatenous bidirectional communication with two orthogonal polarizations.