Circularly Polarized Fabry Perot Cavity Antennas with Peripheral Roughness in Superstrate Unit Cells

Fabry Perot cavity (FPC) antennas have been extensively researched and developed for their reduced fabrication complexity and cost as compared to other high gain planar antennas. Recently, the partially reflecting surfaces (PRS) of the FPC antennas have been engineered with metasurfaces with desirable electromagnetic properties in order to reduce their profile dimensions. These surfaces usually consist of an array of unit cells that are skillfully designed in order to obtain high bandwidth or desired polarization. In this paper, we have considered a unit cell design of a rectangular loop with a diagonal - with an objective of achieving circular polarization. Then we introduced a new design parameter in the form of peripheral roughness in the edge of each of the unit cells. We demonstrate that the incorporation of the new design feature in the unit cell results in an enhancement of the return loss bandwidth to 202.8 MHz (8.9%) and gain to 9.5 dBi along with a reduced axial ratio of 4.8dB.