Study On Method Of Moments Of Electric Field Integral Equation At Low And Intermediate Frequency

With the development of modern science and technology, the calculation and analysis of complex electromagnetic characteristics have received extansive attention. Since the 1960s, computers and computational electromagnetic have considerably developed. A number of electromagnetic solutions appeared, such as finite element method, finite difference method, method of moments and the charge simulation method. At present, the method of moments based on the integral equation is considered one of the most effective methods of electromagnetic radiation and full wave simulation.However, when electric field integral equation is used to solving the problem at very low frequency or the targets subdivision size is far less than the wavelength, there will be a low-frequency breakdown problem. The essential reason of low-frequency breakdown is finite machine precision, which leads to the loss of the vector potential that is much smaller than the scalar potential in the conventional EFIE, the rest of the scalar potential information cannot fully describe the surface current distribution so the matrix ii-conditioned. Although the low-frequency breakdown can be solved by increasing the computer calculation accuracy, a novel approach to fundamentally solve the issue is needed.Nowadays, there are some methods for low-frequency breakdown, such as current and charge integral equation (CCIE), augmented electric field integral equation (A-EFIE), loop-tree or loop-star decomposition, multiresolution and so on. As an effective method to solve low-frequency problem, the core idea of A-EFIE is separation of the current and charge density and discretation by different basis funcitons. In this paper, A-EFIE is adopted to analyze the scattering problem of conductor in free space and radiation problem of layered passive circuits.The contribution of this dissertation:To solve the low-frequency problem of EFIE, pyramid-shaped function, pulse function, RWG bais function and BC basis function are used into A-EFIE, which obtained several effective and stable discretization form. Using a triangle-triangle method and polynomial interpolation method based on chebyshev in method of moments, which is greatly improving the speed and efficiency of the calculation of the MoM matrix. Research on the multilayered Green function with calculating the derivative form of it and obtain its spatial domain form by a novel sommerfeld identity.