Wideband SIW Based Frequency Selective Surface using Exponential Tapering Technique

In this paper, a new design approach is proposed for a frequency selective surface (FSS) based on surface integrated waveguide (SIW) technique using exponential tapering. Here, the unit cell of the FSS is an exponentially tapered cross-slot structure designed on either side of a low-loss substrate. The FSS exhibits good angular stability for TE and TM polarizations up to 30 0. The FSS element shows ≈ 34% wide bandpass response in the X-band region i.e., −3 dB transmission bandwidth from 8.69 GHz to 12.07 GHz, with low insertion loss of 0.1 dB and sharp roll-off characteristics. Extensive studies on various design parameters such as exponential tapering factor and via dimensions are performed using HFSS full-wave EM solver. To validate the proposed FSS design, a low-cost FR4 substrate is used for fabrication, and the measured results are compared to the corresponding simulation results.