Angular-stable and polarization-independent frequency selective structure with high selectivity

We present a three-dimensional bandpass frequency selective structure (FSS) with high selectivity and wide out-of-band rejection. Furthermore, the structure is insensitive to the variation of incident angle and polarization of a striking plane electromagnetic wave. By studying the electric fields and currents excited in the proposed structure, it is revealed that four resonators are constructed to produce the desired filtering response. Experiments show that the fabricated FSS has a 3 dB fractional bandwidth of 18.75% for the passband and a bandwidth of 268.25% for the upper out-of-band rejection better than 20 dB under the normal incidence. (C) 2013 AIP Publishing LLC.