A compact square loop-based frequency selective surface for ultra-wideband applications

Abstract In this paper, a novel compact Frequency Selective Surface (FSS) with an extensive stop-band response has been designed for ultra-wideband (UWB) applications. The FSS structure features a novel modified convoluted square loop with inward bending elements, optimizing its performance. The proposed FSS achieves an impressive bandwidth of 11.64 GHz, spanning from 5.89 to 17.53 GHz. Its compact unit cell dimensions are 0.117 λ 0 × 0.117 λ 0 , where λ 0 represents the free-space wavelength at the lowest resonance frequency. Notably, the FSS provides a −10 dB fractional bandwidth of 96.52%, ensuring robust angular stability up to 60° for both TE and TM polarized waves. A prototype was fabricated to experimentally confirm the simulation results.