The Research Of Microwave Imaging Technology And Inexact Newton Algorithm

Microwave imaging technology is an important part of nondestructive testing, it bases on the research of microwave spreading and scattering in a variety of complex mediums. Microwave imaging technology obtains the electromagnetic characteristics, geometric shapes, space position and other physical parameters of scattering objects by using the inverse algorithms. The content is composed of two parts: one is numerical simulation, which calculates the electromagnetic field distribution for the given model; the other is inverse problem that reconstructs the distribution of electric parameters according to the numerical value of measured scattering field. The inverse problem is the core part of microwave imaging technology, which plays an important role in many fields, such as nondestructive testing, biomedical imaging, geophysical exploration, radar imaging and environmental monitoring.To solve electromagnetic scattering problem, finite element analysis method is is adopted in this paper which is on the basis of electromagnetic scattering theory. The APDL language of finite element analysis software ANSYS is used for program development, in order to simulate that plane wave incidents into the reinforced concretes in which threr are single or double steel bars. The volume of the reinforced concrete model is 0.08m×0.08m×0.08m. And then, sample the data on the sample path. The position information of the steel bars can be obtained, through drawing the graph of scattering data, and which proves the correctness of simulation method.This paper studies and discusses the principle, characteristics and the scope of application for several typical imaging algorithms by reviewing the existing microwave imaging algorithms. An Inexact Newton Method is applied to solve the electromagnetic inverse scattering problem. Such algorithm is composed by two nested loops: in the outer one the nonlinear scattering equations are linearized and in the inner one the linearized equation is solved by means of Landweber method. This algorithm is used to solve the inverse problems and to display the position of steel bars. After limited iteration, the dielectric contrast distribution of the reinforced concretes model can be reconstructed accurately. At last, this method has little error and high precision through analyzing the error, satisfies the requirement of subject, proves the correctness and superiority of the algorithm.