Study On Array Radar Forward-looking Imaging Techniques

Owing to higher spatial freedom,array radar system has the ability of accurate angle estimation as compared to traditional single-channel radar.Thus,it can be introduced to airborne or missile-borne radar forward-looking imaging procedure to improve azimuth resolution,which is hardly achieved by Synthetic Aperture Radar(SAR)or Doppler Beaming Sharping(DBS).Compared with the real beam imaging method,array radar forward-looking imaging technology can further improve azimuth accuracy of the target in forward-looking area,leading to effective improvement of the clarity of the forward looking image generated by moving platform radar.This thesis focus on array radar forward looking imaging technology.The main contents are summarized as follows:1.Array radar forward-looking imaging technique based on super-resolution method is studied.The model of echo signal for forward-looking array radar is established and the traditional MUSIC algorithm is improved with modification and spatial smoothing technique to distinguish the coherent sources.After that,an array radar forward-looking imaging algorithm based on the improved MUSIC algorithm is proposed,with its detailed signal processing discussed.At last,simulation and experimental results are employed to verify the validity of proposed algorithm to obtain forward-looking imaging.2.Array radar forward-looking imaging technique based on linear prediction method is studied.In order to solve the problem of lack of samples for covariance estimation,linear prediction extrapolation method based on AR model are proposed to extend the length of physical antenna array which can improve azimuth resolution of forward-looking imaging.To analyze the feasibility of data extrapolation for improvement of azimuth accuracy,two algorithms for linear prediction,i.e.,the auto-correlation algorithm and the Burg algorithm,are employed to deal with simulation and experimental data.3.Array radar forward-looking imaging algorithm based on compression sensing method is studied.The airspace sparse representation,the sparse signal reconstruction conditions and algorithms for forward-looking array radar are analyzed in detail.After that,this algorithm is applied to forward-looking imaging in the condition of less samples support.Finally,the performance of the proposed algorithm is evaluated by simulation and experimental results.