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.

Keywords

• Satellite communication
• full duplex
• frequency-selective surface
• metasurface
• circular polarization
• antenna