An FSS-based Conformal Band-stop Filter Design for Planar and Non-planar Surfaces

This paper presents a frequency selective surface (FSS)-based conformal bandstop filter design for use in different types of planar and non-planar surfaces. The unit cell of the proposed geometry is based on a single metallic square loop printed on a dielectric substrate. The overall structure exhibits a bandstop response in the frequency range of 6.68 to 12.66 GHz, with a center frequency at 9.53 GHz. The topology is initially analyzed with respect to circuit modeling, surface current distribution, and parametric variation. Afterward, the structure is studied under different types of non-planar surfaces (x-axis curve, y-axis curve, xy- axis curve, hemispherical surface) using the finite element boundary integral (FEBI) method, and the bandstop filter response is observed across the operating band (with transmission coefficient < −10 dB) for all cases. The matching between the planar and non-planar responses confirms the conformal behavior of the proposed FSS structure.