Studies On Coupling Model And Analyzing Techniques For Complex Transmission Line Network

With the rapid development of electronic information technology, more and more electronic devices are integrated in one system. For these equipments in the electrical network varying, the wiring harness plays an important role. However, the potential electromagnetic interference(EMI) which induced by the coupling of transmission line network(TLN) are becoming more difficult to predict. On the one hand, the power surge or the transient electromagnetic pulse as the lumped sources is imposed on the transmission line. Usually, these sources contain rapid rise/fall time, short duaration and high appmplitude. It’s very difficult to analyze the electromagnetic characteristics of the transmission line system efficiently and accurately by using the traditional method. On another hand, the radiation from various antennas or the pulse like HPMP as the distributed soures is imposed on the wiring harness within the platforms. However, how to accurately predict and quantitatively analyze the EM coupling between field line circuit using numerical tools on the huge platform are still challenges to computational EM researchers. Hence, setting up the coupling model and developing effectively analyzing method for TLN become significant whether in theoretical field or in engineering research field. This paper, on the base of classical transmission line theory, major efforts have been expended on the investigation of fast numerical algorithms for reducing the time consuming and memory requirements in classical transmission line solver. Another contribution is developed a hybrid time domain model for analyzing the coupling of wiring harness in the platforms. The aspects concerned are as follows:1, For the sake of simplifying the complexity of the wiring harness analysis, a novel electromagnetic topology based on COG has been described detailly, and the criterion has been deduced too. In order to analysis of the TLN which contains non uniform lines in frequency domain quantitatively, further studies have been focused on a hybrid BLT FDTD method.2, Aiming at analyzing nonlinear circuits including transmission lines, a novel hybrid higher order Finite Difference Time Domain(FDTD)(2,4) and Modified Nodal Analysis(MNA) method has been developed. Different from traditional methods, the higher order FDTD(2,4) can utilize coarser cell sizes for calculation of electrically long transmission lines because of the lower numerical dispersion errors. By constructing a hybrid single port network model, the distributed parameter systems are separated from lumped circuits, so the higher order FDTD(2, 4) and MNA can be used to analysis of transmission line and port circuit transient response respectively.3, A novel Crank Nicolson FDTD method based on the Split Step scheme is proposed and applied in the area of transmission line solving for the first time. Further studies are carried out to investigate the numerical stability and dispersion characteristic of the algorithm. Compared to the conventional unconditional stable FDTD methods, the proposed approach generally achieves lower phase velocity error for coarse temporal resolution by utilizing the precise split time step technique. So larger time scales can be chosen for the transient simulation to achieve accurate results efficiently.4, An improved circuit model for the sensitivity analysis of transmission lines has been constructed based on the former higher order FDTD(2, 4) method. As a direct special temporal discrete method, it does not need to decouple multiconductor transmission line(MTL) and is straightforward to be used in modeling nonuniform MTL. In addition, a modification central difference schem is employed to eliminate the spurious oscillations of the numerical results.5, A comprehensive time domain model for analyzing EMI phenomena on complex structures which involved electrically large platforms, shielded cables and complicated printed circuit boards is developed. It hybridizes the field solver as TDIE accelerated by PWTD, the MTL solver drived from FDTD(2, 4) with the circuit solver rooted in MNA method. The analysis of field coupling into RG 58 coaxial cable located on a submarine is presented. Furthermore, a high efficiency software based on the techniques studied in this thesis has been developed for predicting the crosstalk of the TLN.