| The analysis of electromagnetic compatibility (EMC) characteristics of complex system is getting more and more difficult, due to the high level integration of modern electric systems and the complex electromagnetic environment. The purpose of this thesis is to develop the EMC analysis techniques of the most important interference paths: antenna coupling (front door) and wire coupling (back door); besides, a methodology which can reduce the calculation complexity is studied, and an EMC analyzing framework for complex system is established.In the first part of the thesis, for the mutual coupling analysis of the antennas on a platform, the marching-on in time (MOT) solver for time domain integral equation (TDIE) is studied. The general process of MOT solver is presented, and two kinds of typical EMC examples are provided to illustrate the applicability of the method. The theory of physical optics and TDIE hybrid method (PO-TDIE) is detailed elaborated, and the application problem in antenna EMC is studied. The computational error will stay in a low level, if the transmitter and the receiver together with their adjacent areas are partitioned into TDIE region.To overcome the error caused by the PO current approximation, a uniform geometrical theory of diffraction (UTD) enhanced PO-TDIE hybrid algorithm is proposed. UTD is applied to calculate the edge effect, to compensate the calculation error made by the PO current approximation. This method can improve the accuracy while maintaining the computational complexity, and the application range of PO-TDIE would be extended.For the antenna mutual coupling problems on electrically large platforms, in the basis of classical MOT solver, combining the diffraction ray tracing concept in UTD, a UTD enhanced TDIE algorithm is proposed. The sources which offer quite small contribution are ignored, and only the contribution of low-order diffraction areas is considered; therefore the computational complexity is reduced much. This method needs reasonable region partition, and all diffraction points should be included in the computation.In the second part of the thesis, for analyzing the cable networks of a complex system, multi-transmission line (MTL) theory is described in detail. The distributed parameters of MTL and the telegrapher's equations are deduced.A method to solve the response of MTL network in frequency domain, BLT (Baum-Liu-Tesche) equation, is studied. Based on it, a method to calculate the crosstalk of arbitrary layout transmission line is proposed. The lines are cut into discrete pieces, ideal junction is imported to calculate the scattering parameters, and the transmission lines are equivalent to multiconductor transmission line network. The method offers a solution for the non-parallel lines'crosstalk. In subsequence, the construction method of BLT equation for MTL networks (MTLN) is presented, to the best of our knowledge, for the first time in China.Subsequently, a method to solve the MTLN in time domain, finite difference time domain (FDTD) method, is studied. The interative equations in lumped and distributed source conditions are deduced in detail.For the purpose to solve the nonuniform MTLN, a frequency domain-time domain combined method, BLT-FDTD, is proposed. The nonuniform parts in the network are solved by FDTD; then the incident wave and reflected wave are separated; the S parameters of these parts can then be obtained. In subsenquence, these parts will act as junctions in the operation on BLT equation; and finally the response of the whole network will be solved out. This method overcomes the inapplicability of the frequency domain methods and the high computational cost of time domain methods, and is capable in the computation of the Nonuniform cable networks.In the third part of this thesis, electromagnetic topology (EMT) is studied. The EMC analysis of a complex system is built up by the following four steps: the topological decomposition, the construction of interaction sequence diagram, the calculation of transfer functions and the integration of the responses in the whole system. The whole issue is decomposed into several relative independent ones; as a result, the complexity will be decreased. In subsequence, based on EMT, and in the requirement of EMC analysis, the electromagnetic interference uniform model (EMI-UM) is proposed. A kind of multi-port network is adopted to describe, uniformly, the interference sources, propagation paths and susceptible devices. The establishing method of EMI-UM is presented, and the characteristics and applicable capacity is analyzed.Finally, application analysis of the techniques studied in this thesis is depicted, according to taking a satellite system as an example; and general process of EMC analysis for complex systems is presented. Besides, efforts are made in the development of the system-level EMC analysis software. The design philosophy, architecture and the realization of the software are elaborated.
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