Transmission upper bound of planar single-layer frequency selective surface

In this study, the transmission of planar single-layer frequency selective surface (FSS) has been studied using modal analysis method, and the maximum transmission that a planar single-layer FSS structure with an innitely thin array can reach is presented. The results show that this transmission upper limit is independent of the array and the element, which indicates that it is impossible to achieve a transmission higher than this upper limit under a given incident and dielectric-supporting condition by the design of the periodic array. As the modal analysis method is an accurate method to solve the scattering problem of planar FSS with an innitely thin array, this upper limit is also independent of the solution method. Results of both numerical simulations and experiments show that the upper limit presented in this paper is strict, but may be hard to attain when FSS is supported by lossy dielectric mediums.