Design And Fabrication Of The Dielectric Loaded Cavity And Monoblock Duplexer

In recent years, with the rapid development from 2G to 5G, it is normal for various mobile network standard to be in coexistence. Therefore, microwave filters, duplexer and multiplexer, that work in different frequency, not only have a huge growth on demand but also strict in requirements. In the complex electromagnetic environment, the filters are required not only excellent frequency-selective, low insertion loss and low ripple of the transmission signal, but also high reliability just like power capacity, volume and temperature characteristics. Because it has become an inevitable trend for using new ceramic materials to improve performance and reduce volume of the filter, special attention to application of microwave dielectric ceramic materials are presented in this paper. Furthermore, based on the frequency planning, two kinds of microwave dielectric ceramic duplexers are designed with the theory and experience.The main results of my work are summarized as following:1. Microwave filters is the basis of duplex design. In this paper, the basic principles of designing microwave filters by using the circuit synthesis method and electromagnetism digitally computing technique have been discussed. In particularly, the synthetic method of generalized Chebyshev filter is discussed. Furthermore, the effect of microwave dielectric ceramics for filter is analyzed. Finally, the general design method for microwave duplexers is presented in this paper.2. In this paper, a 3G-WCDMA duplexer is designed as an example for exploring the design and fabrication of dielectric loaded cavity duplexer. Furthermore, the coupling coefficient and resonator frequency of cavity duplexer are discussed with ADS and HFSS simulation software. Finally, the cavity duplexer is improved by introducing ceramic load and transmission zero.3. In this paper, a DCS-1800 monoblock filter is presented with design approach. Using the circuit synthesis and electromagnetism analysis the monoblock dulplex with ADS and HFSS. Furthermore, the influence of structure parameters on the resonance freqency and the coupling coefficient are presented. The ripple of designed monoblock filter is less than 0.5d B, the insertion loss of designed monoblock filter is less than 3d B, and the stopband atteuation is over 25 d B(f=f0±30MHz).