Design of SIW cavity models to control the bandwidth of frequency selective surface

Abstract

This study describes substrate integrated waveguide (SIW) cavity models to control the bandwidth of frequency selective surfaces (FSSs). Two different SIW cavities were presented: one model to reduce (cavity-I) and another model to improve (cavity-II) bandwidth of FSS, respectively. The periodic structures were made of SIW cavies and an FSS slot on either side of the dielectric substrate at the centre of the cavity. To prove the concept, a well-known cross-slot FSS element has been studied in two different cases and compared their performance. The conformal behaviour of the unit cells has been estimated by considering the practical requirements. The addressed SIW cavities will improve the electromagnetic (EM) performance of conventional FSS without altering its basic shape. The high Q-factor of SIW cavity greatly improves the performance of FSS. A full-wave simulation is used to analyse the response of FSS. The cavity-I shows 12.61% lesser bandwidth and cavity-II shows 25.0% higher bandwidth compared to its conventional shape in planar form and 9.1, 26.17% in the conformal form at a bent radius of 50 mm. Besides, performance parameters were studied to evaluate the structural dependency on EM performance. Finally, two designed cavity models are fabricated and proved their performance experimentally.