Research On Imaging Technology Of Through-the-wall Radar Based On Time Reversal

Time reversal is a technique for achieving selective focusing by performing an inverse operation of the echo signal in the time domain(corresponding to a conjugate operation in the frequency domain)and then radiating to the detection region again,due to its good adaptive space time.Focusing ability is introduced into the field of electromagnetic detection and applied to radar target imaging.Compared with the traditional radar imaging method,it can achieve precise target positioning and high imaging resolution,so it has great research value.Based on time reversal technology,this paper mainly studies the application of this technology in through-the-wall radar imaging.(1)Basic theory based on time reversal technology,the multipath and space-time focusing characteristics of time reversal technique are demonstrated by analyzing the principles of wave equation,Born scattering and time reversal mirror.In addition,the time-reversal mirror imaging method and the time-reversal imaging algorithm based on subspace technology are deduced and simulated,and the performance of different algorithms in imaging resolution is analyzed.(2)The application of ESPRIT algorithm in time-reversed radar imaging is studied.In view of the problem that the existing signal-based subspace-based time reversal method has low imaging resolution and the TR-ESPRIT algorithm echo acquisition is complex,the advantage of frequency sampling based time reversal method in echo acquisition and processing is considered.In this paper,the time-reversed FF-ESPRIT algorithm combined with ESPRIT technology is proposed to solve the shortcomings of the above methods.The experimental results show that the proposed algorithm still has excellent imaging resolution under certain noise conditions.(3)The application of time reversal technology in through-the-wall radar imaging is studied.Firstly,the derivation and verification of the Green's function of layered media is given,which is of great significance for the time-reversal technology to achieve accurate target location of the through-the-wall radar.Secondly,the time-reversed through-the-wall radar clutter is solved by using time window and space window.Suppress the problem;finally,the time-reversed FF-MUSIC algorithm based on frequency sampling is introduced into the through-the-wall radar imaging,compared with the traditional backward projection algorithm and the synchronization-based time reversal algorithm,the proposed algorithm has higher resolution for through-the-wall radar imaging.