Leaky-wave explanation of gain-bandwidth-enhanced Fabry-Pérot Cavity antennas formed by a thick multilayer partially-reflective surface

A leaky-wave (LW) explanation of gain-bandwidth-enhanced Fabry-Pérot Cavity (FPC) antennas formed by a thick multilayer partially-reflective surface (PRS) is studied. We first propose a multilayer PRS resulting in a wideband FPC antenna. Then the wideband radiated beam characteristics of the FPC antenna are interpreted based on a LW excitation model. The LW dispersion diagram is provided that explains the wideband FPC operation. It is shown that the FPC antenna bandwidth enhancement corresponds to having multiple optimum frequency points in the dispersion curve of the leaky waves, where the phase and attenuation constants are equal.