Substrate Integrated Waveguide (SIW) involves the conductive via holes immersed in a dielectric substrate that connects two substrate plates. This article presents a new SIW technique to enhance the operational bandwidth of the Riblet Short-Slot coupler. To demonstrate the proposed SIW technique, two Riblet Short-Slot couplers are designed and investigated at two different high-frequency ranges, Ku-band and K-band. The bandwidth of the proposed couplers is improved by introducing multiple layers of SIW vias at the center of the couplers’ side wall. Applying this approach minimizes the leakage loss between vias, indicating an improved overall operating bandwidth of 36.31% and 26.32% for Ku-band and K-band, respectively. All vias in both prototypes are realized using an alternative method, without using the Plated-Through-Hole Printed-Circuit-Board (PTH-PCB) machine. In addition, experimental results agree well with the simulated results.
