Investigation of millimeter-wave scattering from frequency selective surfaces

A comparative numerical and experimental analysis of scattering from dielectric-backed frequency-selective surfaces in W-band (75-110 GHz) was carried out. The examples studied include metal (aluminium), resistive (bismuth), and bismuth-loaded I-pole or linearized Jerusalem cross arrays on fused silica, all of which exhibit a band-stop resonance in W-band as a general feature. The arrays were fabricated using standard photolithographic techniques. The numerical analysis involves the solution of an electric field integral equation using subdomain rooftop basis and testing functions within the framework of the Galerkin testing procedure. The lossy nature of the materials was fully accounted for. A comparative analysis of doubly stacked aluminium I-pole arrays was also performed. The numerical analysis exploits a variant of the cascade method in that the immediately adjacent dielectric layers are included in the construction of the scattering matrix for the frequency selective surface. This allows the higher-order evanescent Floquet modes to decay sufficiently at the dielectric boundaries so they can be ignored in the scattering matrix