3D Near-field Imaging Using MIMO Radar

High resolution three dimensional(3D)images can be acquired by the planar MIMO array radar,which plays a significantly role in military and civil applications,such as through-the-wall imaging and airport surveillance,due to its rapid data acquisition ability.In these mentioned applications,the short distance between target and antenna results in large coherent integral angle and high range curvature,which are classical characteristics of near field imaging scene.Phase center approximation(PCA),as a conventional method for MIMO array analysis,however,is not efficient in near field.Besides,Range migration algorithm(RMA),though able to correct the high range curvature with a large aperture scope,cannot be applied to the arbitrary MIMO array any more.3D imaging technique is studied based on the near field planar MIMO array signal model in this dissertation,including the near field planar MIMO array time-domain and frequency-domain imaging algorithm,the side-lobe reduction method,and the MIMO array design method.Firstly,with the stepped frequency signals,near field planar MIMO array signal model is derived based on the theory that spherical wave can be decomposed into infinite planar wave,which provides a solid support for the near field planar MIMO array time-domain and frequency-domain imaging methods.Meanwhile,the error caused by near field PCA is analyzed,and amplitude attenuation factor is derived to represent the error effect.Simulation results demonstrate that the proposed amplitude attenuation factor can represent the error of near field PCA effectively and correctly.Secondly,3D Back Projection(BP)imaging method is used for MIMO array near field imaging,and the imaging resolution is analyzed based on the formulation of the BP method for typical array configuration,the 3D BP imaging methods is verified by the experimental results of planar MIMO array.Then the relationship of Adaptive Sidelobe Reduction(ASR)parameters,filter order,interpolation factor and threshold,are analyzed;a more appropriate parameter selection method is proposed to improve the ASR methods.The proposed method overcomes the disadvantages mentioned above and is verified by simulation and experimental results.Finally,spatial spectrum of Synthetic Aperture Radar(SAR)and MIMO array is derived to obtain a uniformed range migration algorithm procedure,and four sampling constraint conditions are concluded for MIMO array configuration,then a planar MIMO array design method is proposed,and the performance of the designed array is analyzed with simulation results.