Circuit Model for a Textile Linear-to-Circular Polarizer using Swastika-Shaped FSS

A circuit model for a flexible linear-to-circular polarizer is proposed. This linear-to-circular polarizer is designed based on the concept of Frequency Selective Surface (FSS) unit cells on one side and a rectangular-shaped conductive strip (CS) on its reverse side. The overall polarizer is implemented on a felt substrate, whereas ShieldIt Super conductive textile is used to form the conductive elements for operation in the S-band. Its principle of operation and its interaction with different orthogonal polarized wave components are first presented, followed by the generation and study of the surface currents to understand the waves in different polarizations. This study is summarized in the form of an equivalent circuit model. To further assess this model, the textile-based polarizer is then simulated using full wave simulations and compared to the results obtained from the proposed circuit model. Both results indicated satisfactory agreement in terms of transmission coefficient. Further analysis of the proposed polarizer using full wave simulations indicated promising results in terms of conversion efficiency and axial ratio. A fractional bandwidth of 7.35 %, operating from 2.36 to 2.55 GHz and an axial ratio of 1.4 dB indicated its operation in the S-band.