Study On Cross-coupling For Band-pass Filter Based On Resonant Cavity

Band-pass filter based on resonant cavity is widely used in various types of electroniccommunication equipment for its’ excellent performance. However, the size of the cavity filters isalways large, especially for those high performance filters which need multiple cavities. Byintroducing the transmission zeros in the stop-band, cross-coupling technology is able to improvethe performance of filters. Moreover, by applying this technology in design, the number of cavitiescan be reduced while the performance remains unchanged. Therefore, this subject has significantpractical value.The research direction of this thesis is to design high performance filters which are based onthe cross-coupling technology and the contents of this thesis are listed as follows:(1) Based on the cross-coupling technology and the substrate integrated waveguide (SIW)structure, a bandpass filter (BPF) with a transmission zero on the lower-skirt of passband and a BPFwith a transmission zero on the higher-skirt of passband were designed, fabricated and measured.The measured results are in accordance with simulated results.(2) The two proposed single-transmission-zero BPFs can be regarded as basic blocks and theycan be cascaded to form a BPF with two transmission zeros which are located on both lower andhigher skirt of passband. A coaxial line was utilized to connect the two blocks and the measuredresults were analyzed.(3) For further size reduction, the half-mode substrate integrated waveguide (HMSIW) cavityand the quarter-mode substrate integrated waveguide (QMSIW) cavity were also be designed andsimulated. Meanwhile, the hybrid cascading of these two cavities was simulated and analyzed.(4) A new kind of cross-coupled BPF, combined with HMSIW cavity and QMSIW cavity, wasalso designed and discussed.