| In today’s increasingly tense frequency resources, the filter, as the selected frequencycomponents, is essential for modern communication systems, its role becoming increasinglyprominent and its performance directly affecting the quality of the whole communicationsystem. General speaking, there are two structures of modern microwave filters:singlechannel and multi-channel structure. The structure of single channel is simple and themulti-channel structure can generate transmission zeros by introducing cross-coupling. Singlechannel structures can use K or J Richard transformation and direct coupling to synthesizeand realize,and the generalized Chebyshev synthesis can realize both structures. Butmulti-channel filter that is a road of Combiner its structure more complex than single-channelstructure,its structure is formed by the combination of two or more single-path filter. In orderto prevent combiner between the various ports interfere with each other, so the parameters ofthe requirements the Port isolation between its various ports also higher. Cross-coupling formulti-channel structure can be introduced to produce transmission zeros, which provide atheoretical basis for the design of the combiner. At present multi-frequency Combiner is in theinitial stage in our country, so this paper is not temporary the field of this.In this paper I am studied the filter the main is synthesis method is most commonlyused method in modern microwave filters. The steps of the synthesis method are as bellows:select a specific filter function approximation.Integrated coupling matrix and simplify to getthe network of the Topology.Select the method to achieve. Simulation and optimization.This paper studies the micro strip and cavity filter design ideas and methods, discussesthe generalized Chebyshev filter theory and summaries the microwave filter design. Based onthese theories, two kind of microwave filters, meeting the requirements, are designed usingHFSS simulation software.Through improved by the introduction of cross-refers to the capacitance of its ordinary hairpin filter, a new structure of the hairpin filter. The sameperformance, compared with ordinary hairpin filter with interdigital capacitor hairpin filtersize reduction of about40%. Cavity filter simulation, the simulation curve of the cavity filter,compare microstrip filter cavity filter curve, given microstrip filter and cavity filter their ownadvantages shortcoming.At the last we can get the conclusion micro strip filter and cavityfilter,some guiding in engineering practice. |
