Leaky-Wave Analysis of Wideband Planar Fabry–Pérot Cavity Antennas Formed by a Thick PRS

The radiation properties of wideband Fabry-Pérot cavity (FPC) antennas have been investigated by studying the non-Foster behavior of the reflection coefficient phase of the thick partially reflective surface (PRS) forming the cavity. In order to better understand the performance of such cavities, we show for the first time that the wideband behavior can be explained via a unique dispersion characteristic of the dominant excited leaky-waves (LWs) inside such cavities. We derive new formulas that demonstrate the role of the LWs in forming wideband FPC antennas when the reflective phase of the PRS exhibits an increase with frequency within the band of operation.