Study of pass band resonance characteristics of aperture type FSS

In this paper, the resonance characteristics of aperture type frequency selective surface (FSS) is presented. A systematic investigation is carried out to design the compact FSS. The optimized structure consists of rectangular Archimedean spiral with inter-digital capacitance. Resonance characteristics is verified in both single-layer as well as the double-layer approach by embedding FSS on one side of the dielectric substrate. The performances of the dual-layer are observed by varying air-gap between two FSS layers. The structure offers satisfactory resonance (transmission and reflection) characteristics at optimum air-gap of 7 mm between two layers with the 3 dB cutoff region over a frequency range (3.66-4.66 GHz). Finally, an array of 31 × 31 FSS elements of two layers is fabricated for experimental characterization. A close agreement between simulated and measured results is observed.