Research And Application Of The Coupling Structure Of Cavity Filters

With the development of microwave communication, radar and electroniccountermeasures, multi-frequent work becomes more and more important. In order tomake more effective use of limited spectrum resources, the requirement to crossoverfrequency becomes higher and higher. Considering the requirement, the development ofmicrowave filter, a kind of frequency selective microwave passive components, receivesmuch more attention.The excellent qualities, such as miniaturization, low loss, high out-of-bandsuppression, high power capacity, ultra wide band, and others are the agree targets of thedevelopment of microwave filter. However, the key to achieve these excellent qualitiesis the new resonant cell and coupling structure. This paper focuses on the couplingstructure of cavity filters and aims to achieve the design, processing and debugging ofhigh rectangle coefficient coaxial cavity filter with the characteristic of high out-of-bandsuppression under high power capacity.The study is conducted through equivalent circuit model, and the theoreticalcalculation methods of the coupling coefficients of filters are summarized and analyzed.Then the superiority of matrix theory in microwave circuit is detailedly introduced, anda new cavity coupling structure and an easy-to-debug cross coupling structure are putforward. At last a high frequency selective coaxial filter with rectangle coefficientsmaller than1.2is successfully designed, and its excellent qualities and applicationvalues are displayed.