Polarization-insensitive ultrathin fractal shaped frequency selective surface for ultra wide band shielding

Abstract

An ultrathin and flexible Frequency Selective Surface (FSS) for ultra-wideband electromagnetic interference (EMI) shielding has been proposed in this article. The novelty of the suggested design lies in its capacitive coupled Greek cross-shaped fractal structure that is printed on a single and flexible layer dielectric substrate having an extremely thin thickness of 0.0013λ 0 , where λ 0 refers to the free space wavelength of the lower cutoff frequency. The introduction of capacitive coupling approach between the modified Greek cross fractal metallic structure and four symmetrical triangularly slotted conventional right-angled triangular metallic geometry results in an excellent ultra-wide stopband (UWSB) of more than 154% (2.07–15.76 GHz) and 105% (4.38–14.05) for < −10 dB and < −20 dB fractional bandwidth, respectively. The conformal configuration of the proposed geometry also exhibits a significantly better bandwidth more than 148.89% (−10 dB) and 109.5% (−20 dB) for UWSB. To accomplish the physical interpretation of the proposed FSS, the equivalent circuit model optimization has been illustrated also. Furthermore, the proposed structure demonstrates strong polarization independence and angular stability under both TE and TM polarization. Finally, the ultra-wideband shielding characteristics of both the planer and conformal designs have been confirmed experimentally in a free space measuring system.