Wideband skewed grid frequency selective surface absorber for oblique incidence

We present a wideband frequency selective surface (FSS) absorber for oblique incidence. The absorber structure with anisotropic elements exhibits different impedances in two polarizations to match free space characteristic impedance at oblique incidence, thus resulting in a low microwave reflectivity over a wideband range. The grating lobe is suppressed by the use of skewed grid. Simulation and measurement results all illustrate that the reflectivity covers a broad band of 1.35-4.0 GHz below −10 dB for both TE and TM polarizations at an incident angle of 45°.