Multiband ultra-thin electromagnetic band-gap and double-sided wideband absorbers based on resistive frequency selective surfaces

Within the realm of metamaterial absorber design, multiband ultra-thin electromagnetic bandgap absorbers and double-sided absorber designs based on resistive frequency selective surfaces (FSSs) have not been widely investigated. In this paper, we present an efficient spectral-domain periodic method of moments (PMM) formulation for the analysis of resistive FSS screens embedded in a stratified medium. We apply a cascading procedure to generate a composite scattering matrix for the entire system consisting of multiple resistive FSS screens embedded in a stratified medium. In addition, the 2-D fast Fourier transform (FFT)-based method was applied to speed up calculation of the required impedance matrix elements. Moreover, an 0(N log N) FFT-based method with 1-D implementation together with the sparse storage technique was employed to accelerate computation of the matrix-vector product within the bi-conjugate gradient (BCG) iterative solver. This hybrid method differs from the 2-D FFT techniques reported in. Finally, this formulation will be applied to the design of multiband ultra-thin electromagnetic bandgap absorbers that operate over a wide range of incidence angles and double-sided wideband absorbers that employ resistive FSS screens.