Analysis Of Multiconductor Transmission Lines And Microstrips On Anisotropic Substrates With The Unimoment Method

With the rapid development of technology and increase of work frequency, the open microwave transmission lines such as microstrips and multiconductor transmission lines should be considered as distributed parametric circuit elements. And their electromagnetic parameters should be extracted for instantaneous analysis, when used as interconnection lines in integrated circuits and microwave integrated circuits. In the present thesis, the improved unimoment method is used to solve the problems of parameters extraction and characteristics analysis of open microwave transmission lines for the first time. By choosing reasonable series of basis functions according to the specific boundary conditions, the region to be calculated can be reduced and the efficiency of the method can be increased dramatically. First, the effectiveness of the method to the extraction of electromagnetic parameters in the open microwave transmission lines is verified by the capacitances computation of the parallel by-conductor transmission lines. Then, the layered multiconductor microwave transmission lines in the same and different mediums, microstrips and coupled microstrips on anisotropic substrates are also analyzed by the unimoment method. For the anisotropic substrates microstrip lines, the characteristic impedances and normalized phase velocities will decrease and the coupling constants will increase as the anisotropy increases. For certain structure, better isolation and directivity can be obtained than those of isotropic substrates if feasible values are chosen.The unimoment method used in the present thesis retains the merits of the finite element method to the electromagnetic problems with irregular and complex media, together with forming sparse matrix, occupying less computer memory. Furthermore, it overcomes the limitation of the finite element method only applicable to the bounded region. Results in this thesis show that the unimoment method is an effective way to the analysis of open transmission lines problems which can extract the electromagnetic parameters of the open microwave transmission lines rapidly and accurately. It also proves that the anisotropic materials are helpful to improve the coupling characteristics of the transmission lines. The work of this paper can provide groundwork for integrated circuit and microwave integrated circuit components design and has important theoretical and practical significance to enrich theoretical studies and engineering applications of microwave transmission lines especially.