High-gain circularly polarized resonant cavity antenna using FSS superstrate

A novel high-gain, circularly polarized resonant cavity antenna (RCA) using a two-layer frequency selective surface (FSS) as its superstrate is presented. In the proposed design, two kinds of FSSs, namely an inductive sheet and a capacitive sheet, are used, both of which are designed to be highly reflective to achieve gain and directivity enhancement. Furthermore, by properly designing the dimensions of these two sheets and aligning them, the linearly polarized wave radiated by the source patch antenna can be transformed into circularly polarized radiation. Based on the operating principles of RCAs, the modeling, design, and characterization of the FSS-based superstrate for use in the antenna are also presented. A broadside peak gain of 13.12 dBi, a flat gain response, and a wide axial-ratio bandwidth of the proposed antenna are achieved.