Three-dimensional broadband bandstop frequency selective structure using dual-mode resonators

A novel three-dimensional (3-D) frequency selective structure (FSS) with broadband bandstop filtering response is presented. The proposed FSS consists of a two-dimensional (2-D) periodic array of double sided strip lines and an array of dipoles. Under a linearly polarized incident wave with its electric field perpendicular to the printed strip lines, dual-mode resonators are constructed, providing a broad stopband with two transmission zeros and a transmission pole at a higher frequency. A bandstop FSS is designed and its frequency bandwidth (S₁₁ ≤ -10 dB) is 106%, in the range from 3.14 GHz to 10.3 GHz. Furthermore, the proposed FSS exhibits stable frequency response under a large variation of incident angle.