Research On High Precision ISAR Imaging Technology With Wide-angle

Wide-angle inverse synthetic aperture radar(ISAR)has acquired higher precision imaging effects with longer observatory observation hours,which is often used to handle non-cooperative target signals in military and civilian applications.At the same time,due to the longer observation time of the wide-angle ISAR,the observation target rotation is more complex,and the scattering anisotropy is significantly interfered with imaging.Thereby,the scattering phase is superimposed with the rotational high order phase,which makes it more difficult to process the phase.Moreover,the factors affecting the scattering characteristics become more and more,so corresponding processing is needed to improve the image quality.In this thesis,the phase and scattering characteristics of wide-angle ISAR are analyzed,and a corresponding solution is proposed respectively.The work of this thesis is as follows:(1)Based on phase characteristics,the relatively comprehensive phase system of ISAR with wide-angle is modeled,and the differences between wide-angle ISAR model and traditional ISAR model are analyzed.At the same time,the scattering characteristics were analyzed,and the model of ISAR scattering center with wide-angle was studied.The anisotropy of scattering of observation targets under wide-angle was analyzed,and the corresponding high-precision imaging method of ISAR with wide-angle was given at last.(2)In order to solve the problem of wide-angle ISAR phase model steps from the observation target rotation,this thesis proposes a large-scale ISAR optimal imaging time period based on phase multiplexing,after the relative linear component of its phase,the relative linearity is high,and the optimum image time relatively simple in the target rotation state can represent the optimum imaging time of the wide-angle ISAR highprecision imaging.The effectiveness of the proposed algorithm is verified by simulation.(3)In view of the anisotropic scattering characteristics of wide-angle ISAR with sensitive changes generated by long-term observation accumulation,this thesis proposes a wide-angle ISAR sub-view partition algorithm based on Gaussian scattering partition.The scattered energy of wide-angle ISAR observation target is divided by Gaussian function.The sub-view with high scattering energy reveals the strong scattering component,while the sub-view with low fluctuation reveals the weak scattering geometric component.Thus,the overall anisotropic scattering of the wide-angle ISAR observation target can be relatively complete.Finally,the effectiveness of the proposed algorithm is verified by FEKO complex scattering target simulation.