Uneven Surface Penetrating Radar Imaging Techniques With Surface Penetrating Radar

Thanks to its capability to quickly and conveniently imaging with high resolution,sensibility to electromagnetic characteristics of targets and ability to detect non-metallic targets,surface penetrating radar is widely used in municipal engineering,archaeological exploration,geological and hydrological surveys,non-destructive evaluation as well as mines and UXO detection and other fields.However,when the target is hidden under the media with uneven surface,the echoes of curved surface is difficult to effectively remove,and the imaging results are seriously deteriorated.It has become a vital problem and restricted the development of surface penetrating radar.The imaging algorithms of surface penetrating radar applied to uneven surface are studied in this paper.Firstly,two models of the surface penetrating radar applied on the uneven surface are briefly introduced.By analyzing the models,two appropriate near-field imaging algorithms are introduced,including ?k imaging algorithm applied to plane scanning model and conformal algorithm applied to the surface conformal scanning model.Secondly,methods to improve the imaging results of plane scanning model are proposed.At first,the interference fringes and interference spot of targets and uneven surface appeared when using continuous waves are briefly analyzed.According to the difference in the raw echo data of the interference effects between gradually uneven surfaces and small goals,an approach to differentiate targets from clutters is proposed.Then a filter is proposed to remove the disturbance of cylindrical surface,and a compensation method on frequency domain for small targets is proposed to improve the imaging results.The algorithm can also be applied in the sphere.The simulation and experimental results have confirmed the effectiveness of the method.Finally,the general model of uneven surface using conformal scanning way is proposed.For surface conformal models,the general solutions are considered to remove the impacts of the inner curved surface echo and layered interface.Then a variety of methods to remove the clutters of cylinder's surface were simulated and compared.At last,taking advantage of special symmetry of conformal hemispherical scanning model,a fast algorithm is proposed and the simulation shows the superiority of this algorithm.