Microstrip Sir Filter Study

As an essential component in modern wireless communication systems,RF bandpass filter has attracted more and more attention and got many achievements too and became smaller and smaller .In this thesis,some research of the design methods and new structures,techniques and miniaturization of bandpass filter in wireless communication systems are proposed .The dissertation mainly including below main contentFirstly, introduces the history of the filter, elementary theory of microstrip transmission line,network theory , the elementary theory and design methods of the filter.Secondly, introducs the main theory of SIR(stepped impedance resonator),some characteristic of the SIR has been discussed,such as resonance conditions, resonator length, spurious (higher order) responses, and equivalent circuits. Then the design methods of the parallel coupling SIR band-pass filter has been discussed,and analysed the different characteristic of the SIR resonator with the different impedance rate.Thirdly, two kinds of the methods to improve the performance of filter stopband has been discussed.These methods are used to cleared up the influence of the parasitical passband.Through the simulation and test result shows that these methods 's performance is expected.Fourthly, discussed the inside coupling resonator's structure and theory, further minish the filter's cubage.Finally, discussed how to use EDA tool to design filter, especially the filter has complex geometric structure.The research productions of this thesis have much reference value on the filter miniaturization , improve the performance of filter stopband and improve the efficiency of the filter design.