Research On Broadband Matching Methods Of Nonreciprocal Transmission Lines

In the field of microwave technology, impedance matching is one of the basic elements in the design of microwave systems. The problem of impedance matching must be considered in order to transmit the signal of generator to the load efficiently and distortionless by transmission lines. The bandwidth of matching networks is an important factor in the design of matching networks. In this thesis, the problems of impedance matching are studied based on the theory of nonreciprocal transmission lines, the broadband matching methods of nonreciprocal transmission lines are put forward.First, the related concepts about theory of nonreciprocal transmission lines are introduced, including the nonreciprocal transmission line equations, the characteristic parameters and some important parameters, which can lay a theoretical foundation for impedance matching. Then, the multiple reflection viewpoint is used in nonreciprocal transmission lines, so the theory of small reflections for nonreciprocal transmission lines is studied in a different way, the accuracy of the theory of small reflections is also verified, which can provide a theoretical basis for designing multi-section transformer.In this thesis, a new method for designing nonreciprocal binomial transformer is deduced from the design method of the traditional binomial transformer based on the theory of small reflection. Its accuracy is verified by practical examples and the existing problem of it is analyzed. According to this problem, an optimization method is put forward; its accuracy is also verified by practical examples. In this way, the broadband matching of nonreciprocal transmission lines is realized. This method can also be used for designing traditional binomial transformer, the practical examples are given.Based on the theory of small reflection, a new method for designing nonreciprocal chebyshev transformer is deduced from the design method of the traditional chebyshev transformer and this method has the same problem. So an optimization method can be achieved by the same method and its accuracy is verified by practical examples. Thus another method for the wideband matching for nonreciprocal transmission lines is realized. This method can also be used for designing traditional chebyshev transformer, the practical examples are given.As mentioned above, studies in thesis have certain practical significance for broadband matching of nonreciprocal transmission lines and the design of multi-section traditional transformer.