Effect of the asymmetry of the dielectric permittivity distribution in the filter response of dielectric frequency-selective surfaces

The main aim of this paper is to analyze the effect of the asymmetric distribution of the dielectric permittivity in DFSS with periodicity in one dimension. In order to proceed, we have introduced additional dielectric slabs inside a basic periodic cell (formed by two dielectric media). The electromagnetic analysis of such structures has been performed employing a recently developed full modal method Coves et al. (2003, 2004), considering the incidence of a plane-wave under three-dimensional incidence. The new structure shows an asymmetric permittivity distribution with respect to the center of the periodic cell. At normal incidence, it involves the splitting of the reflection peak into two different resonance peaks associated with the rupture of degeneracy of the +1 and -1 leaky modes due to the asymmetry of the relative permittivity distribution. Nevertheless, when we introduce an additional dielectric in the periodic cell in a symmetric way, the reflection response of the filter shows again a single resonance peak. We also analyze the angular response of the filters at three-dimensional TE incidence at the resonance frequency.