A New Miniaturized Active Frequency Selective Surface with Convoluted Element for UHF Applications

Abstract

This paper presents a study on Active Frenquency Selective Surface (AFSS) for applications in modern wireless communication systems. Initially, an FSS with an element inspired by convoluted metallic lines printed on a dielectric substrate of FR-4 is proposed. The unit cell size is equal to 10.2 % of the wavelength in free space for the frequency of 1.53 GHz. An equivalent circuit model is proposed to better understand the operating principle of the FSS. Four Schottky diodes have been inserted in a symmetrical manner for switching, and three operating states are analyzed (all diodes in off state, all diodes directly polarized and therefore conducting, and two diodes conducting and two diodes off). The reconfiguration allows the frequency response to vary between frequencies from 0.8 GHz to 2.5 GHz. The FSS proved to be stable with respect to the angle of incidence of the plane wave on the circuit surface. The simulated numerical results for the designed prototype was obtained by ANSYS HFSS software. The prototype was built and the experimental characterization of the transmission coefficients, bandwidth and resonance frequency was performed. The values obtained in the experiment were compared and discussed with the simulation results, which showed good agreement.

Index Terms
Active Frequency Selective Surface; AFSS; equivalent circuit model; Schottky diodes