Design of high-impedance screens by using multilayered frequency selective surfaces

In this paper, a multilayered dielectric structure backed by a perfectly electric conducting (PEC) ground plane is investigated for realizing high-impedance surfaces. These surfaces behave like a perfect magnetic conductor (PMC) at a certain frequency range. The inclusion of an FSS in the structure provides an additional degree of freedom which can be exploited to obtain the desired frequency and angular performance. All the presented solutions are derived by using a genetic algorithm-based synthesis procedure. The genetic algorithm (GA) resorts to an electromagnetic solver based on the method of moments (MoM) to describe the scattering behavior of the structure. In particular, the GA determines the permittivity and the thickness of each dielectric layer and the shape and the dimensions of the FSS screen. The synthesized structures arc discussed with particular reference to the frequency response and to the robustness of the solution with respect to the angle of illumination.