A new class of frequency selective surfaces

A structure comprising a perforated screen with double connected apertures is studied using an efficient two-step procedure. The radiation of the array of patches is evaluated by a Green´s function relative to the perforated screen with simply connected aperture A´, embedded in a stratified dielectric support (the reference structure). Pursuing this idea, the patches P are removed by the equivalence theorem and substituted with an unknown distribution of electric current. Then, the scattering problem is solved by enforcing the vanishing of the electric field on the patches. An important point in this procedure is that the Green´s function of the reference structure is determined by the aperture approach described in by R. Orta et al. (1988). Hence, the most natural approach is used for each substructure and no cascading procedure is needed. An example of results with the proposed method is given.<>