Coupling modeling and reduction techniques of cavity-backed slot antennas: FDTD versus measurements

Cavity-backed slot (CBS) antennas are commonly used in Earth-based and space-borne applications. In this manuscript, the finite-difference time-domain (FDTD) method is used to analyze different antenna characteristics of such elements including input impedance, coupling, and radiation patterns. Emphasis is given to coupling calculations, especially to different methods to reduce coupling. Specifically, coupling reduction is attempted using lossy material superstrates or ground plane discontinuities, such as slits. Numerical issues concerning the analysis of CBS antennas in the context of FDTD are also discussed.