Research On Multilayered Wall Imaging Method Of Through-the-wall Radar

Through-the-wall radar(TWR)system can accurately locate the target behind the obstacle and retrieve the detailed information of the target.In practical applications,the electromagnetic wave needs to penetrate the wall to image the hidden target behind the wall.However,the wall may be composed of multiple layers of media or multiple single-layer walls are separated by a hallway,so the detection process of TWR often encounters the nonuniform multilayered walls.For TWR imaging methods,the imaging reconstruction time represents the timeliness of the system.In addition,the influence of environmental noise on the echo data cannot be avoided and the anti-noise ability is very important to the stability of the imaging method.To solve the above problems,this thesis has the research contents as follows.1.Research the multilayered wall imaging method of TWR based on the total variation minimization(TVM).In the process of imaging reconstruction,the dictionary matrix is constructed by calculating the far field Green's function of the multilayered media.Based on the sparseness of the gradient domain of the reconstructed image,the TVM technology is adopted to achieve the sparsity-based imaging reconstruction.The simulation experiment results show that compared to the BP imaging algorithm and the L1-norm minimization based sparse reconstruction algorithm,the proposed imaging algorithm can not only reduce the imaging reconstruction time,but also can retain the geometric shape and edge information of the target and have the good anti-noise performance.2.Research the TWR stolt migration imaging method for multilayered wall.A multilayered wall imaging algorithm based on stolt migration is proposed for pulse TWR system.The proposed imaging algorithm first converts the multilayered media imaging reconstruction to the single-layer medium imaging reconstruction based on the exploding model and wavefield propagation extrapolation technology,and then achieves the imaging reconstruction by interpolation and fast Fourier transform technology.The simulation experiment results show that the proposed stolt migration imaging algorithm can quickly and accurately reconstruct the concealed target behind the multilayered wall in the noisy environment.