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 the Surface Integrated Waveguide (SIW) technique using exponential tapering. Here, the unit cell of the FSS is an exponentially tapered crossslot structure designed on either side of a low-loss substrate. The FSS element shows nearly 34% wide bandpass response in the X-band region i.e., $-3 \mathbf{d B}$ transmission bandwidth from $8.69 \mathbf{~ G H z}$ to 12.07 GHz, with low insertion loss of 0.1 dB and sharp roll-off characteristics. 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.