An Optimized and Compact Bandstop FSS for C, X, Ku and K bands

In this letter, we present a single substrate layer compact wide bandstop frequency selective surface (FSS) for the C, X, Ku, and K bands that is polarization insensitive and has higher angular stability upto 45 degrees. An optimized circular slot in a square patch is cut in the upper conductive layer, and diagonally cross dipoles in a square ring are placed in the lower conductive layer. With a fractional bandwidth of around 150%, this proposed layer provides wideband rejection across the entire band ranging from 3.5 GHz to 25 GHz. This structure is printed on both sides of a FR4 substrate using the smallest unit cell dimension possible (
$0.064\lambda\times 0.064\lambda\times 0.009\lambda$
). In HFSS, a detailed parametric study for factors influencing FSS response was conducted. The compact configuration allows the planar bidirectional wideband antenna used for satellite communication, ground penetration, and astronomical purposes to be made unidirectional by reflecting waves radiated towards the FSS.