Research On Ultrawideband Radar Imaging Algorithm Using Linear Electromagnetic Inversion Techniques

GPR (ground penetrating radar, GPR) as a new type of target detection and recognition technology, which has the advantages of fast testing, nondestructive, and high accuracy and so on, is widely applied into the areas on underground target imaging, detection of bridges and tunnels, archaeological exploitation, geological exploration and prevention of geological disasters and so on. The imaging of GPR underground objects is the basis and key point of the target detection and identification. In recent years the methods of electromagnetic inverse scattering radar imaging become hotspot and also get in-depth study in the areas of target inversion imaging. Because electromagnetic inverse scattering imaging exists nonlinear and ill-posed nature, although using iterative algorithm can make the target to image. It is heavy computation, high calculation cost and difficult to meet the needs of practical engineering applications. So the study of linear electromagnetic inverse imaging algorithm has a higher value in practical engineering. On these problems, this article has mainly researched the Born approximation linear and the direct sampling algorithm of electromagnetic inverse imaging, which mainly contains the following aspects:Firstly, it is presented the research of the algorithm of Born approximation linear electromagnetic inverse imaging. According to the underground propagation theory of electromagnetic wave, it is acquired the nonlinear integral equations of the electromagnetic inverse scattering. For weak scattering medium, the electromagnetic inverse scattering nonlinear integral equations is transformed into linear integral equation by using the Born approximation theory. It can acquire the general expression of Dyadic Green Function by using Green’s Theorem, and be designing and numerical calculation for Green’s Function. Through constructing a matrix, solving integral equations is converted into solving matrix equations, using TSVD optimization methods and Tikhonov optimization methods solves ill-posed nature in electromagnetic inverse scattering imaging.Secondly, it is studied the algorithm of direct sampling electromagnetic inverse imaging. According to the Green’s Function and Delay Sampling Theory, it is analysis and Numerical Calculation for direct sampling method, and for the first time direction sampling method is applied into GPR, which can realize the target object inversion imaging.