Metal And Nonmetal Combination Of Target Time-domain Integral Equation Method

Because of the large advantage in the analysis of electromagnetic scattering and radiation problem, using the time domain integral equation (TDIE) solving every structure of objects'scattering become to an important direction in Computation Electromagnetics, But The classical MOT(marching-on-in-time)-based TDIE solvers have a drawback: the late time stability problems. Many scholars in China and foreign countries have tried to improve the drawback, but it is difficult to deal with it effectively. In this paper, we will introduce an accurate and stable method which bases on MOT to solve dielectric objects and metal-nonmetal composite objects.First, every form of TDIE is described in detail. The general implementation of time-domain integral equation solver is presented. The details that relate to the method of moments (MOM) used to solve the TDIE are discussed. Furthermore, numerical algorithms used to solve the linear system are introduced.Next, after briefly discussing several causes of the late-time instability of the TDIE solvers, a novel viewpoint about the instability is proposed. The marching-on-in-time algorithm (MOT) is described and some temporal bases are discussed. Due to the importance of the accuracy of the time-domain impedance matrix elements, the techniques by which treating of the singular integrals and near singular integrals arose from the TDIE-MOM solving process are analyzed in detail, and these techniques are utilized to solve the TDIE.In the end, using triangle patches discretizing arbitrarily 3-D dielectric objects and metal-nonmetal composite objects surface and utilizing spatial RWG and temporal triangular bases, the TDIE are solved by MOT algorithm. Several numerical results show that the proposed method is stable and accurate, and it is nearly not sensitive to the high-, low-frequency component of the incidence wave.The research work presented in this dissertation provides an efficient approach to analyze the dielectric objects and metal-nonmetal composite objects'transient electromagnetic scattering phenomena, as well as a solid foundation for the further development in this subject.