Design Of Cross Coupled Dielectric Duplexer

With the rapid development of mobile communication technology and the scarcity of communication frequency resource, microwave passive devices such as microwave filters and diplexers are becoming more and more important. Because the microwave filters have a crucial influence on the quality of the whole communication system, the requirements of their performance are also getting higher and higher. So the current key technical requirement is developing the filters with small size, high performance and low cost in a short period of time.The cavity filter is widely used because of its advantages of small volume, high performance and easy to realize, at the same time the microwave dielectric ceramic materials are also being developed and applied in the cavity filter. According to the basic theory of cavity filter and dielectric resonator, we studied of cavity filter deeply and designed a coaxial cavity filter and a dielectric resonator filter respectively, compared the performance of these two cavity filters, and made a brief description on the simulation of the power capacity estimation and temperature conpensation for microwave resonators. Based on the above design and research, we summarized a set of fast filter design method by collaborative simulation using a variety of software. On this basis we also designed a ceramic dielectric duplexer used in WCDMA frequency band and verifed the effectiveness of the fast filter design method by an example.The novelty of our topic duplexer design lies in the introduction of dielectric loaded and the cross coupling. We used high quality factor of microwave dielectric ceramic materials to make no-load Q value increase greatly and reduce the insertion loss. We also introduced the cross coupling between the cavity to reduce the cavity number and improve the band rejection which realized the device miniaturization and high performance. To compare with the same frequency coaxial cavity duplexer, our design has significant advantages.