Synthesis of Spatial Band-Pass Filter Based on Frequency-Selective Surfaces

This article presents a synthesis process of a spatial band-pass filter based on frequency-selective surfaces (FSS) using specially developed software. A correlation between the filter based on frequency-selective surfaces, equivalent quasipolynomial filter and Chebyshev band-pass filter is shown. A synthesis process and calculation results of the third order filters of various implementations are presented. An amplitude-frequency characteristics comparative analysis of the synthesized filters based on FSS with characteristics of various LC-filters has been performed. Sizes of frequency-selective surface cells are subwavelength, that allows to create structures with small thickness. An electrodynamic model of the spatial filter was built based on calculation results of a single frequency-selective surfaces element. Transmission and reflection coefficients of the spatial filter based on frequency-selective surfaces were calculated. The calculated characteristics have a good matching with characteristics of equivalent LC-filters. The synthesized filters can be used as phase-correcting elements of the transmitarray antennas or the low-profile scanning antenna systems. The thickness of the frequency-selective surface structure depends on operating wavelength, filter order and initial values of capacities and inductances.