Fast BP And Diffraction Tomographic Algorithm For Through-the-wall Radar Imaging

Through-the-wall radar imaging(TWRI)technology has been widely applied in a large variety of areas such as anti-terrorism reconnaissance,urban operations,disaster rescue etc.The traditional imaging techniques consist of infrared imaging,thermal imaging,ultrasonic detection and optical imaging.However,the electromagnetic-wave has the good penetration ability to ensure the robust behind-the-wall target detection and imaging.Previously,some effective TWRI methods such as back projection(BP)algorithm,diffraction tomography(DT)algorithm,time reversal(TR)algorithm and compressed sensing(CS)algorithm etc have been developed.This paper mainly aims at researching and improving the performance of the BP and DT imaging algorithm.The BP algorithm has been a hot research topic in TWRI area because it can conveniently compensate for the refraction phenomenon of the layered medium.However,the core of BP imaging principle is delay-sum of each pixel in the imaging area,so there is a high computational load for the traditional BP imaging algorithm.The traditional BP imaging algorithm usually requires to taking the long time to obtain high resolution imaging of behind-the-wall scene.To solve the above problem,a novel fast nonuniform fast Fourier transform(NUFFT)based BP imaging algorithm for TWRI is proposed in this paper.The proposed BP imaging method can significantly reduce the reconstruction time while simultaneously maintaining the image quality of the investigation area.It can be a good candidate imaging algorithm for real-time imaging applications.With the increase of the complexity of the reconstructed scenario,the imaging reconstruction through a single homogeneous wall cannot meet the needs of the practical engineering application.The paper has researched the electromagnetic inverse scattering theory based DT TWRI algorithm.By exploiting the spectral form of planar multilayered medium and the exploding source model,a first order Born approximation based DT imaging algorithm is proposed in this paper.The proposed imaging method can implement the fast and accurate imaging reconstruction of the target concealed behind the multilayered wall.The effectiveness and validity of the proposed DT imaging algorithm have been verified by processing the synthetic data generated by the finite difference time domain(FDTD)method.