By using modal matching

frequency response of frequency selective surfaces （FSS） with apertures is studied for zero thickness and infinite planar conducting sheet. The excitation is assumed to be a plane wave incident at any arbitrary angle. Based on Floquet theory

the solution is obtained by matching the tangential field components at the surface of the screen. Both single and double-FSS configurations are studied and the effects of multilayered dielectric substrate are taken into account. Then

the typical results of the influence of the lattice

element configurations and incidence angle on the performance of FSS consisting of arrays of cross-loop slots are summarized.