Research And Implementation Of Cavity Filter Based On Hybrid Resonance Method

Microwave filter is a communication device with the filtering function of frequency,It's often used in the field of mobile communication.However,with the development of high-tech technology,it has a higher demand for wireless mobile communication technology,especially the coming 5G wireless communication,the requirements of market will not only to miniaturization and low cost,and require the lower insertion loss,the higher band suppression,the higher performance,the higher frequency selectivity and more ideal rectangle coefficient and so on.Based on the present mature microwave filter design technology,by specifying several transmission zeros in the transfer function S₂₁1 to improve the near-end suppression and the frequency selectivity of the filter pass-band,the method that improving the Q of the resonator has used to reduce the insertion loss of the filter in the band,which make the filter performance more ideal.Therefore,the two common methods were combined in this paper,and several transmission zeros were specified by simulation,and the dielectric resonator was used instead of the metal resonator which in a specific position,Thus a high-performance cavity filter with metal and dielectric resonator had designed.The specific contents of this article was summarized as follows:Firstly,based on the function theory of generalized Chebyshev filter,the filter predistortion technology was fully researched and analyzed.The function relation between Q and filter characteristic index had be deduced,and then studied the simulation between Q and insertion loss,return loss and rectangular coefficient in the equivalent circuit.Secondly,Through the general topology simulation of CT and CQ which make transfer zeros,obtained the distribution law of the mixed cavity filter with dielectric resonator.Then a hybrid coupling structure was designed,It solved the problem that the coupling between the metal and the medium is not normal due to the orthogonal direction of the electromagnetic field,at the same time the coupling coefficients of the resonator were obtained by the Y-matrix method and then realized the coupling between the different resonators.Finally,this thesis adopt different schemes which under the same index but there kinds of topology,Completed the simulation between them and processed the whole cavity filter,then complete the corresponding debugging and testing.It's concluded that the Q of the zeros has the greatest influence on the filtering performance,and also verifies the feasibility of the mixed cavity filter and the improvement of the filter performance.