Several Researches On Microwave Inverse Scattering Imaging

Electromagnetic inverse scattering problem is an important branch of inverse problem,which has a wide range of application prospect.In this dissertation,we focus on electromagnetic inverse scattering imaging problem.First,the electromagnetic inverse scattering problem of 2-D scatterer under oblique incidence is investigated.Through considering the coupling between TM and TE modes,a new imaging algorithm is proposed which can solve 2-D inverse scattering problem with arbitrary incident polarization under arbitrary incident angle.The influence of the polarization of the incidence and the incident angle is analyzed through numerical simulation.The results show that,although there is coupling between TM and TE modes under oblique incidence,the cross polarization component has small impact on the imaging quality.This indicates that through properly choosing the polarization of the incident wave and the scattered wave,the microwave imaging system can be simplified without seriously deteriorating the imaging quality.A microwave imaging system for oblique incidence scenario is designed and realized.The proposed algorithm is proven to be effective with experimental data.Second,the inverse scattering problem with inhomogeneous background is investigated,where there is little experimental research.Four strategies are proposed by considering the non-ideal factor in practice.Experiments are performed using a setup with the object surrounded by a closed wall.Successful imaging on the object surrounded by a closed wall is achieved.After a comparison of the results of different algorithms,it shows that SOP-inhomo-based methods are able to generate better imaging results with experimental data.At last,the inverse scattering problem with limited view is investigated which is common in practical application.A method is presented to improve the imaging quality with limited view.Through setting a reflective plane behind the target,the information loss can be compensated.The scattering model of a target close to a conductor plane is built according to the image theory.The imaging of targets close to a conductor plane is achieved.The influence of limited view and placing a conductor plane close to the scatterer is investigated.Numerical results show that the imaging quality when there is only limited observation directions can be improved by properly placing a conductor plane close to the scatterer.The research results can be used in the design of microwave imaging system.