Bandpass 3-D Frequency Selective Surface with High Selectivity and Wide Out-of-Band Rejection

This work presents a bandpass three-dimensional frequency selective surface (3-D FSS) that realizes high selectivity and wide out-of-band rejection with simple structure. Using microstrip resonators, we design a third-order FSS operating at 5.0 GHz from 4.67 to 5.29 GHz, with -20 dB fractional bandwidth of 11.0%. The application of cascaded triplet (CT) topology brings in cross coupling that generates a transmission zero on the lower skirt located at 4.56 GHz. The proposed FSS shows wide out-of-band rejection capability over 9.0 Ghz. The simulation results of the proposed FSS are in good accordance with theoretical calculation.