Design of Compact Polarization Insensitive Triple Bandstop Frequency Selective Surface with High Stability under Oblique Incidence

Abstract

This paper proposes a novel design of a triple band frequency selective surface (FSS) that acts as a bandstop filter at 1.92 GHz, 3.5 GHz and 5.64 GHz. The bandstop frequencies resemble to GSM, WLAN and WiMAX application bands respectively. The structure is polarization insensitive since its frequency response remains unaltered for both TE and TM modes of electromagnetic wave propagation. The main attractive feature of the structure is its highly stable response under oblique incident angle upto ± 800 at both TE and TM polarizations. Surface current distribution and equivalent circuit modelling are presented to demonstrate the resonance characteristic of the FSS. The structure is compact with an overall unit cell area of 0.09λ x 0.09λ, where λ is the wavelength corresponding to the lowest resonant frequency. The proposed structure is compared with other multi-bandstop FSS structures in literature to highlight its superior functionality in terms of stability under oblique incidence and compactness. A prototype comprising of 6 x 6 array of the proposed unit cell is fabricated and the measured results are in good agreement with the simulated results.