Three-dimensional bandpass frequency selective surface with quasi-elliptic responses

Abstract

A new three dimensional (3-D) bandpass frequency selective surface (FSS) with quasi-elliptic frequency response is proposed for dual-polarized application. Each unit cell is based on the coaxial waveguide (CW), and provides two propagation paths which are the CW and parallel-plate waveguide (PPW). By resonances and interaction of these two propagation paths, the proposed FSS can obtain three transmission poles and two transmission zeros. Furthermore, the material with higher dielectric constant is used in PPW path. Meanwhile, by using a polygonal inner conductor and outer conductor with ridges in the CW path, a wider stopband can be realized at higher frequencies. A design example shows a good performance and a smaller unit cell size compared to previous work which uses identical material in these two paths.