Research On High Power And High Isolation Multiplexer For Communication

Multiplexers are indispensable microwave devices in modern communication systems. The multiplexer approximately contains several filters with frequency bands adjacent and intersecting to each other. In the communication, the harmonics or parasitic modes fall into the adjacent channel and the intermodulation generated by it will form unnecessary interference, seriously affects the communication quality, thus improving the isolation between the transceiver and other channels is the emphasis and difficulty of the multiplexer design. Because of the low efficiency of the current full-wave simulation software and the complexity of debugging, it is indispensable to establish a precision model simulation and debugging environment and a rigorous method used to modify the simulation model and adjust the tuning element. In order to solve the above problems,this paper has done the following work.First, based on the cavity model, the resonance of the cavity is studied by using the field structure and the mode distribution. With the single cavity model the distribution of electric field and magnetic field in cavity and the effect of tuning rod size on cavity resonance and energy storage are illustrated. Through the double cavity model, the influence of the cavity resonance on the adjacent cavity and the change of the coupling structure to the resonant cavity are studied. The input port will effect the whole performance of the entire structure, so this paper use the method of group delay combined cavity resonance to analyze its impact. The design of the common port and the first cavity of the channel is critical to the isolation of the multiplexer channel, so it is analyzed by a four-channel and dual common cavity model. Those provide a theory for the design of multiplexers.Second, against the optimization variables too many and the complexity of the structure, the improved Cauchy method and the genetic algorithm are used to map the space to connect the physical space and the theoretical equivalent space to realize the fast extraction of the coupling parameters. By extracting the coupling parameters and calculating the error, the multiplexer physical model is modified to improve the design efficiency. It lays the foundation of the multiplexer and filter automation design and intelligent hardware quick debugging platform.Third, a multiplexer has been designed based on the previous research results. By redistributing the channel, the multiplexer contains nine bands in the form of a double passband. Eventually it presents one input port and five output.Multiplexer is an important part of the communication system. The isolation of the communication channel and its ultra-wide bandwidth structure are the difficulties in the design. The study of its internal field and model is necessary for both design and debugging. The space mapping model proposed in this paper can facilitate the design of multiplexer.