A Multi-layered Frequency Selective Surface-Based Wireless Filter with Dual Bandpass Response

Abstract

The design of a multilayered bandpass frequency selective surface (FSS)-based wireless filter with narrowband as well as wideband frequency response is presented in this paper. The proposed FSS is designed by cascading two metallic patch type layers with split ring shaped slot and one grid layer with two dielectric substrates in between. The proposed design exhibits second order bandpass response in the 6-7.7 GHz band with two transmission poles at 6.4 GHz and 7.4 GHz and another transmission pole at 3.3 GHz is achieved due to the slots in the patches leading to another passband. The structure is low profile with the horizontal and vertical periodicities of unit cell on the order of λ0/13 with respect to lowest resonating frequency. Transmission phase of the FSS reduces linearly with frequency in the 6-7.7 GHz band which makes it useful for enhancing the broadside radiation of an antenna over wide bandwidth when used as a superstrate above the radiator.