A Novel Three-Dimensional Frequency Selective Surface With Stable Resonance

In this paper, a novel three-dimensional (3-D) Frequency Selective Surface (FSS) which is independent of incident angle is proposed. By mapping circular aperture unit elements of two-dimensional (2-D) FSS to spheres, an innovative 3-D FSS which contains annular aperture unit elements is designed. Through controlling structure parameters, the resonant frequency shift characteristics of the proposed 3-D FSS under oblique incidence can exhibit opposite tendency, which provides a possible way to offset the resonant frequency shift of the dielectric slab caused by different incidence angles. The performance of the proposed 3-D FSS loaded with dielectric slab demonstrates excellent resonance stability over a large range of oblique incidence, and the resonance frequency remains constant for different incident angles, even valid up until 80 degree.