Design of a band-pass FSS with steep-rejection stopband by equivalent circuit method

This paper presents an equivalent circuit method (ECM) to design a band-pass frequency selective surface (FSS) with a steep-rejection stopband. The FSS shows a passband at X-band and a stopband at Ku-band. Using the basic FSS structures of grid and square loop, whose impedance properties have been studied in depth, we construct the multilayer model of FSS element corresponding to the equivalent circuit method. By analyzing the circuit, we can obtain the analytical formulas of scattering (S) parameters for the FSS elements, which are suitable for both normal- and oblique-incidence. With the curve-fitting method, we can determine the dimensions of the element, and complete the primary design of the FSS. Finally, we compare the analyzing results with the simulation results by Ansys HFSS, and the method is proved to be feasible for fast design of FSS.