Circular Polarization and Reconfigurability of Fabry-Pérot Resonator Antenna Through Metamaterial-Loaded Cavity

In this paper, a Fabry-Pérot resonator antenna (FPRA) with a metamaterial-loaded cavity is presented. The proposed antenna preserves the simplicity from single resonant cavity and linearly polarized (LP) feed. A 3-D-printed all-dielectric metamaterial structure with hybrid locally periodic patterns is placed between the superstrate and the ground plane. The loaded metamaterial provides a new configuration for achieving self-generated circular polarization (CP) for the FPRA. Owing to the fact that the generation of CP relies solely on the anisotropy of the metamaterial, independent control of the axial ratio (AR) and directivity becomes possible, thus avoiding potential tradeoffs to be made between the AR bandwidth and the directivity increment. In addition, further polarization agility between CP and LP states can be obtained by employing different angular rotations of the metamaterial with respect to the feed antenna. The proposed concept is verified through a design example carried out at around 10 GHz showing an overlapped impedance and AR bandwidth of 6.7% (from 9.6 to 10.27 GHz). The design considerations are given with the help of performing the ray-tracing analysis. The agreement between the measurement and full-wave simulation justifies the validity.