An original analysis of Fabry–Perot cavity antennas based on thick partially reflecting sheet (PRS) is presented in this work. The bandwidth enhancement of such radiating devices with respect to Fabry–Perot cavity antennas based on thin PRS has been investigated through a leaky-wave, transverse-equivalent-network approach, and a field matching technique. This analysis led to an optimal condition for considerably improving the gain-bandwidth figure of merit for this class of radiating devices on a sound physical basis. A Fabry–Perot cavity antenna based on a thick PRS working at 60 GHz is discussed as a case study. An excellent impedance matching is finally achieved by means of an efficient feeding network designed through a fast ad hoc, hybrid, analytical-numerical method. Theoretical results are in an excellent agreement with full-wave simulations corroborating the proposed methods.
