Design Of SIR Bandstop Filter And Dual-band Bandstop Filters

With the high speed development of wireless technology and the limited spectrumresources became very crowded, modern communication system required higherperformance bandstop filters. Some communication equipments were dual-bandoperation, dual-band filters have become key front devices of them. SIR bandpass filterand dual-band bandpass filters have been researched many years, and lots of researchachievements have been obtained and reported, while SIR bandstop filter and dual-bandbandstop filters were researched late. In this thesis, the main research contents are theSIR bandstop filter and dual-band bandstop filters.Firstly, the research status of bandstop filter and dual-band bandstop filters wereintroduced. Then, frequency transformation, Kuroda transform, basic form bandstopfilters and design formula of coupled resonator bandstop filter were presented. Furthermore, the bacis structure and characteristic of SIR were introduced as the basic theories.Secondly, two resonance structures, the spur-line and embedded open stub wereanslysed, simultaneously their equivalent circuits and resonance characteristics weregiven. With SIR, spur-line SIR and embedded SIR were proposed, at the same time theirequivalent circuits were given. Two compact spur-line SIR and the embedded SIRbandstop filters with good harmonic suppression were designed. Ultimately, theembedded SIR bandstop filter was fabricated and measured, from its experiment resultsknew, compare with the embedded shunt open-circuited stub bandstop filter, its spuriousstopband appeared latter about one octave, and the filter size reduced about20%.Thirdly, hairpin-comb SIR structure was ultilized to design a hairpin-comb SIRmicrostrip bandstop filter, compare with the traditional L resonator bandstop filter, it hassmaller size and plentiful design parameters. Then according to the bandstop filtercombination method, a dual-band bandstop filter has been designed, it could be used inplanar circuit for integration and miniaturization.Finally, A novel dual-mode ridge waveguide resonator was introduced. Then, therevolving cross-type ridge dual-mode resonator was used to design a cavity dual-modedual-band bandstop filters, simultaneously its topology was given. Ultimately, the dual-mode dual-band cavity filters were fabricated and measured, the results of thesimulation and experimentation were matched very well. This is a good attempt to usedual-mode resonator to design cavity dual-mode dual-band bandstop filters.