;This thesis presents meandering feeding structures based on substrate-integrated waveguide cavities and apply it to single-band bandpass filter, multi-band bandpass filter, and multiplexer design. The thesis utilizes meandering distributed feeding lines as input and output ports. Based on this structure, two different forms of bandpass filters are realized. Due to its low loading effect, the bandpass filters can be easily extended to multi-channel design. Compared to traditional microstrip T-junction or common-junction cavity, the proposed architecture offers more flexibility in selecting specifications. For example, the center frequencies of a multi-band bandpass filter or multiplexer can be chosen easily. Additionally, each passband can be independently controlled in the multi-channel design. By using circuit simulation tools, the single-band bandpass filters can be quickly integrated into a multi-band bandpass filter or multiplexer. Furthermore, in the last chapter of this thesis, this structure is extended to a wide-stopband diplexer. Overall, there are 9 different circuits proposed in this thesis and the difference between simulated and measured results are also discussed in this thesis.
