Cross Coupled Substrate Integrated Waveguide Filter With Quasi-Elliptic Response and Wide Stopband

This article proposes a new technique for the cross coupled substrate integrated waveguide (SIW) filter to achieve a wide stopband in addition to a quasi-elliptic response. It exploits the field distribution properties of spurious modes in multilayers to prevent them from transmitting through both the main and cross coupling paths without affecting its quasi-elliptic fundamental passband, as opposed to the previously reported designs that can suppress spurious modes only in their main coupling path. An example is provided. Without using a hybrid structure that compromises the superiority of SIW, and with a shielding structure that is suitable for high-performance and high-frequency applications, it achieves a quasi-elliptic response with multiple transmission zeros (TZs) and a wide stopband with adequate suppression. The proposed technique should be effective for developing SIW filters in microwave and wireless circuits and systems.