Scattering from three-dimensional cavity-backed apertures in an infinite ground plane by RBCI

This paper describes an extension of the Robin boundary condition iteration (RBCI) method to solve the problem of scattering from three-dimensional cavities embedded in an infinite ground plane. The proposed method is a hybrid one since it combines a differential equation for the interior and the neighborhood of the cavities with an integral equation for the rest of the unbounded domain. A suitable choice of the boundary condition (of the nonhomogeneous mixed type) on the fictitious boundary dividing the two parts of the domain avoids resonances whatever the frequency. Moreover, an iterative solver is described for the efficient solution of the discretized global system of linear equations.