Research On The Design Method Of Duplexer Based On Ceramic Dielectric Filled Resonant Cavity

With the rapid development of modern communication technology,the integration degree of communication equipment is also increasing.Higher requirements for design of high performance,miniaturization and compact microwave devices are put forward in communication RF front-end system.In this context,it is of great significance to study the high performance and miniaturization of microwave diplexer,a key device in communication system.The traditional metal cavity diplexer usually restricts the high integration of RF system due to its large circuit volume,so it is urgent to realize the high performance and miniaturization design of diplexer.In recent years,attributing to the continuous improvement of material development technology,ceramic dielectric materials exhibit higher quality factor,extremely low temperature drift coefficient and a variety of optional relative permittivity.Therefore,the design of high-performance and miniaturized microwave devices based on ceramic dielectric materials is attracting more and more attention from scholars at home and abroad.Under this circumstance,this paper has carried out the research of high-performance and miniaturized diplexer based on the ceramic filled cavity.By using the common port of the common cavity and the surface metallization process of the rectangular ceramic surface,combined with the synthesis theory of diplexer,three different types of diplexers are designed and implemented.The specific research contents of this paper are as follows:1.Firstly,the research background of diplexer and the research status at home and abroad are introduced,and the significance of this paper is clarified.Then it introduces the basic theory related to diplexer and this paper,including the basic principle and index parameters of diplexer,microwave network theory,transmission function of filter and basic synthesis theory of filter and diplexer,which lays the foundation for the research work in this paper.2.Secondly,a design of laminated diplexer based on ceramic filled cavity is proposed.The coupling matrix of diplexer is synthesized based on the processing method of common port on common cavity,the arrangement of resonant cavities in upper and lower layers,the coupling topology and technical index requirements.And the ADS equivalent circuit is established to verify the coupling matrix.Afterwards,the mode characteristics and coupling mode of the cavity are analyzed.The initial dimensions of the cavity and coupling window of the diplexer are simulated by HFSS eigenmode.Combined with the group delay response characteristics of the diplexer,the whole cavity of the diplexer is optimized and adjusted by the method of collaborative simulation.The proposed diplexer has the properties of compact structure,excellent performance and miniaturized design.3.Thirdly,a design of the folded type diplexer based on the ceramic filled cavity is proposed.By using the processing method of common port on common cavity and the singlelayer folded cavity arrangement form,combined with higher design index requirements,the diplexer design with better performance of passband selection and more concise structure is completed,and the processing test is carried out.Then,the cross coupling theory of diplexer is introduced.According to the characteristics of folded physical structure,the cross coupling structure of CQ type is introduced to complete the optimal design of diplexer,which realizes better out of band suppression characteristics and higher pass band isolation.