A double-layered C-band frequency-selective surface bandstop filter for maritime communication

Abstract

ABSTRACT In this paper, a dual-bandstop frequency-selective surface (FSS) implemented using a four-legged Minkowski square and s hexagonal ring is presented. The proposed FSS shows dual stopbands at 4.9 GHz and 7.1 GHz in the C band. The size of the unit cell is 0.36λ0 × 0.36λ0, which is designed on an FR4 substrate with a thickness of 1.6 mm and a loss tangent of 0.02. The frequency response of the bandstop FSS is verified using circuit simulation, and its optimised dimensions are determined at the desired frequencies of operation. The results reveal that the ratio of the two stopband frequencies can be adjusted over a wide range by properly selecting the geometrical parameters. The impedance bandwidths for S11< –10 dB of 0.9 GHz and 1 GHz have been realised at the lower and upper frequency bands, respectively. A prototype is fabricated and measurements show a reasonable agreement with the simulated results, thus validating the design concept. It has been shown that the proposed bandstop FSS exhibits excellent stability upto 60° at oblique incident angles in both TE and TM polarisations. This FSS is suitable for C-band maritime applications due to wide stopbands and highly stable angular operation.