Scattering properties of antennas residing in cavities filled by inhomogeneous materials via a variational formulation

Inhomogeneous media exhibit many properties that are very useful either in microwave circuits or in radiation components. In this paper a scattering analysis of cavity-backed microstrip patch antennas with inhomogeneous slabs is proposed. An equivalent variational formulation of the electromagnetic problem for this kind of antenna is derived, such that a very efficient Finite Element Method-Boundary Integral code can be straightforwardly applied. Numerical results are compared with those known in the literature showing an excellent agreement with them. The main scattering properties of the inhomogeneous substrates are also pointed out and compared with those of homogeneous substrates.