A Linear to Circular Polarization Converter Based on Split-Rectangular Ring Frequency Selective Surface

A transmission polarization converter is described that is based on frequency selective surface (FSS) to convert the incident linearly polarized wave to a circularly polarized one. This polarization converter consists of four layers and contains two different unit cells. The structure has helped in achieving desired nearly a high transparency to two orthogonal components of transmitted waves while providing nearly 90º phase difference, as required for the generation of circularly polarized fields. The polarization converter offers axial ratio of less than 3 dB over 76.8%, from 9.2 GHz to 20.7 GHz. In addition, its working frequency band can still cover the range of 9.7 GHz to 20.1 GHz when the incident angle increases to 20°. Theoretical analysis and results of numerical investigations related to the structure are presented.