Approximate Analysis Method for Frequency-Selective Surface Based on Kirchhoff-Type Circuit

A novel approximate method based on the Kirchhoff-type circuit for frequency-selective surface (FSS) analysis is presented in this paper. Instead of splitting up the array element and solving a higher order impedance/admittance matrix equation in the periodic moment method, the equivalent transmission line method is adopted to obtain analytical solutions of the normalized receiving current (or magnetic current) distribution for pattern functions. The impedance/admittance elements and transmission coefficients can then be analytically calculated using Munk's scheme. The proposed method can be applied to generic FSS elements composed of relatively narrow straight slots/strips. The revision scheme of the equivalent transmission line lengths is proposed to account for discontinuity effects at corners of the element. The transmission coefficients of the six biplanar symmetric hybrid radomes are computed to verify the accuracy and efficiency of the presented method.