Research On The Filters And Antenna Matching Network Based On Minimum Mismatching Network

After 180 years of development, circuit theory is still vibrant. With the development of electronic information technology, circuit theory has penetrated into various fields, promoting technology development and human progress. With the increase of operating frequency, broadband matching theory’s match means differently in the radio communication system. Common matching network design only considers the impact of network parameters changes on the system performance, but neglect the impact of load variation. In order to study the impact of load changes on the matching network performance, minimum mismatching network theory is proposed. Minimum mismatching network is a network whose transmission characteristics are insensitive to the terminal load which is time-varying. Minimum mismatching network can be taken as the extension of broadband matching theory.Problems to be solved are:Seeking minimum mismatching network solutions, determining the conditions of analytical solutions, solving the problem, and finding ways to apply minimum mismatching network to the special design of the matching network. Based on the minimum mismatching network theory, minimum mismatching filters, lossless and lossy minimum mismatching antenna networks and adaptive matching network were designed with the combined use of theoretical calculations and numerical simulations. The main contents are as follows:(1)The network functions and characteristics parameters of minimum mismatching network are studied. Input reflection coefficient modulus as the optimal objective function was proposed on the basis of the minimum mismatching network theory. The key parameters were analyzed. It describes the basic idea and design process of genetic algorithm and non-dominated sorting genetic algorithm Ⅱ.(2)Three specific filter characteristics of Butterworth, Chebyshev and Elliptic are studied. The passive minimum mismatching low-pass filter and coupled resonator band-pass filter were designed by optimization algorithms on the basis of the minimum mismatching network theory. The characteristics of minimum mismatching filter with varying load were analyzed. It was compared with filters built up with other methods. It is proved that network characteristics of the minimum mismatching filter are insensitive to varying load.(3)The input reflection coefficient modulus and transmission power gain of lossless and lossy antenna matching networks are analyzed. Multi-objective optimization algorithm NSGA-Ⅱ for lossless matching network, lossy network loaded with II-type attenuator constituted by pure resistors, and irregular lossy network loaded with parallel RLC were optimized respectively. The simulation results show that lossy network get the ability to suppress load changes at the cost of gain reduces.The relative bandwidth loaded with Ⅱ-type attenuator of minimum mismatching network is increased to 60%. The irregular lossy network loaded with parallel RLC will ensure suppressing load changes. At the same time, the antenna efficiency in a wide band is increased to 50%.(4)Through the analysis of the network topology, Ⅱ-type network which is composed by the variable reactance elements were selected as the tunable matching network. A new analytical algorithm was proposed. The goal of the algorithm is to make the input reflection coefficient modulus smaller. The network characteristics is ensured insensitive with varying load. If the requirement is not met, the algorithm is to make the transmission power gain larger. According to circuit theory, the analytic relations of each matching network component values are studied. The adaptive network elements with varying load are realized.