ABSTRACT
This chapter reviews the operation of Fabry—Perot cavity (FPC)-based antennas, aims to compare with that of metamaterial-based designs, and highlights the common role played by leaky waves in establishing the main radiation properties of the antennas. It describes FPC-based planar directive antennas, examines the relevant literature, and discusses the alternative models that can be adopted to explain their operation. The chapter presents the high directivity attainable with antennas placed in low-permittivity substrates and aims to compare the relevant geometrical-optics and leaky-wave (LW) models. It considers various aspects of the radiation from simple electric or magnetic sources placed inside grounded metamaterial slabs, including conditions on the constitutive parameters for maximizing the power density radiated at broadside and for achieving high directivity. The chapter also presents a comparison between FPC-based and metamaterial-based LW antennas in terms of pattern bandwidth and directivity.
