Double-layered siw filter with enhanced electric coupling structure using three short-ended striplines

This paper presents an electric coupling structure with enhanced coupling coefficient based on double-layered SIW cavity resonators. Short-ended striplines are used to achieve electric coupling between two SIW cavities. The electric coupling depends on the width of the stripline. The proposed structure can achieve coupling coefficient more than 0.14. A fourth-order cross-coupled filter having centre frequency of 9.7 GHz and fractional bandwidth of 12% has been designed to verify the structure.