| With the development of wireless communication technology and the maturity and popularization of 5G technology,microwave multiplexer,as a frequency selective device that can separate and synthesize signals,has been widely used in satellite communication,radar system and radio frequency modulation and other fields.Due to the increasingly tight spectrum resources,the performance of multiplexer is more and more demanding,and its design difficulty is gradually increasing.In order to adapt to the increasing difficulty of multiplexer design,this paper will carry out the following work around the design of multiplexer:1.In order to provide a theoretical basis for the subsequent design of multiplexer,the design of filter is firstly studied in this paper.Firstly,the filter characteristic polynomial synthesis method based on generalized Chebyshev function and the theory of filter coupling matrix synthesis are introduced,then the optimization algorithm of filter which can realize arbitrary topological coupling matrix is studied,and the design of filter synthesis software is completed according to these theories.Because using dual-mode filter as the channel filter of the multiplexer can greatly reduce the overall size of the multiplexer,the design theory and implementation method of dual-mode filter are also studied in this paper,and some improvement strategies are proposed for the higher out-of-band interference of dual-mode filter.2.Star-point multiplexer is often used in the field of wireless communication because of its simple structure.Traditional optimization methods are prone to fall into local solutions because of too many optimization variables in multiplexer,so this paper will study some improvement strategies to redesign the optimization algorithm.Firstly,the method of directly using the synthesis result as the initial value of optimization is abandoned.By studying the synthesis method of coupling matrix of terminating complex impedance filter,the optimized initial value is redesigned considering the influence of other channels.Secondly,the adaptive differential evolution algorithm is used to improve the probability of global solution by adding adaptive operations to the differential evolution algorithm.Finally,the number of variables in each optimization is greatly reduced by using the strategy of distribution optimization,so as to improve the convergence speed and optimization effect of the algorithm.Based on the proposed algorithm,three examples of multiplexer design are given to verify the practicability of the algorithm.3.Due to the small size and insertion loss of multiplexer required by satellite communication,manifold-coupled multiplexer is often used.Because the manifold-coupled multiplexer cannot be obtained by analytical algorithm at present,this paper designs an optimization algorithm for the manifold-coupled multiplexer.Firstly,the design method of singleterminal filter as channel filter is introduced.Then,how to calculate the return loss at the common port and the coupling coefficient of each channel according to the characteristics of the multiplexer is studied.Finally,the optimization method of manifold-coupled multiplexer is designed based on the step optimization strategy and verified by an example. |
