Influence of dielectric layers on performance of transmission mode frequency selective surface based linear to circular polarization transformers

In this article, we investigate the electromagnetic behavior of freestanding and dielectric embedded frequency selective surface (FSS) based linear to circular polarization convertors. The two structures were designed to operate in transmission mode at normal incidence and yield the lowest value for axial ratio (AR) at frequencies around 10 GHz. In addition to providing mechanical robustness, a 72% increase in the 3 dB AR bandwidth (BW) is achieved when the 140‐μm thick perforated FSS sheet is inserted between two 5‐mm thick polytetrafluoroethylene (PTFE) slabs. At oblique incidence a downward shift in frequency is observed, however the BW is still significantly larger than the results obtained for the freestanding periodic array within a field of view of ±30° in the cardinal planes. Spectral transmission measurements presented for both anisotropic media verify the simulated results.