Study On Electromagnetic Scattering Of 3D Structures Based On Finite Element Method

With the development of society and the change of the international situation, the role of science and technology has became more and more prominent, especially in the modern war. Among them, the radar is undoubtedly the focus of development, because it is called modern war glasses. In the design of radar system, study on the electromagnetic scattering characteristics of target is an important basis of research. For modern fighter stealth design, target classification and identification, early warning and tracking and other military applications ,it is extremely important reference value. Finite element method (FEM) is widely used in the numerical calculation of electromagnetic scattering. In practical application, a lot of electromagnetic scattering and radiation problems are related to the infinite region, then the finite element method to set up the appropriate boundary conditions at a distance away from the target position, thereby increasing the amount of calculation. Although the boundary integral method based on integral equation can be directly analyzed the target problem, but ultimately to generate a full rank matrix, the computer memory and computation requirements higher, cannot be applied to electromagnetic problems in large size. In order to apply these two numerical simulation methods, the finite element boundary integral method is developed. By introducing a fictitious boundary can be applied to the practical electromagnetic problems, with boundary segmentation, internal boundary using the finite element method and boundary integral method is applied to the boundary, and according to the continuity of the coupling field. It is necessary to study and apply the finite element boundary integral method to deal with the problem of large-scale infinite domain. The main work of this paper is divided into the following three points:1. Firstly, the basic principle of the vector finite element method is introduced, and the finite element method is further understood through the analysis of the waveguide problem. In this process, the final field and transmission coefficients are obtained by the discretization of the grid, the interpolation function, the imposed boundary conditions,the sparse matrix storage and the solution of the matrix. And through the comparison with HFSS simulation results, the error size is calculated, and then a detailed overview of the finite element method is given.2. In the electromagnetic scattering and radiation problems, they are concerned with the infinite space, and the application of finite element method must be infinite by artificial boundaries truncated to finite region, including absorbing boundary conditions(ABC) and perfectly matched layer (PML), this paper uses the first order scattering vector calculation the three-dimensional structure of target absorbing boundary conditions. Through the judgment of the convergence rule model, compared with HFSS simulation results, and calculate the radar cross section RCS and the analytical solution is verified their procedures, and get some complex models of RCS, so as to complete a set of applicable to arbitrary three-dimensional structure model of the program.3. Finally, the introduction of the finite element boundary integral solution of electromagnetic scattering problems, is deduced by the polarization and polarization in two ways, the expressions of matrix equations and matrix elements, and the two general models were calculated, including the double station RCS, and the data and results of detailed comparison.