Research On High-resolution Imaging Methods For Multistatic Synthetic Aperture Radar

Synthetic Aperture Radar(SAR)is widely used in civil and military fields because of its all-time and all-weather two-dimensional high-resolution imaging capability.Multistatic SAR imaging technology can obtain a high-resolution radar image in a short time depending on coherently synthesizing its spatial distributed apertures,which is of great significance for the high-resolution observation of movable targets.This thesis focuses on the problem of high-resolution multistatic SAR imaging,quantitatively analyzes the effect of continuous apertures and discontinuous apertures on the multistatic SAR imaging performance and mainly studies the key issues,including the echo model and high-resolution imaging methods.The main contents are as follows:1.This thesis establishes an echo model for multistatic SAR.The target range history of multistatic SAR is derived,and the echo signal characteristics are analyzed.Then,the preprocessing steps are studied.The echo model lays a theoretical foundation for performance analysis and imaging methods of multistatic SAR.2.This thesis studies the mapping relationship between the wavenumber spectrum of multistatic SAR and the point spread function.The influence of aperture distribution on the coherent imaging quality of multistatic SAR is analyzed,which reveals that the discontinuous apertures will lead to a defocused point spread function.3.This thesis proposes a high-resolution imaging method based on data extrapolation for multistatic SAR.According to matrix pencil approach,the method extrapolates the gap data caused by discontinuous apertures in wavenumber domain,which compensates the discontinuous wavenumber spectrum into a continuous wavenumber spectrum.The proposed method can be applied to solve multistatic SAR high-resolution imaging problem of discontinuous apertures with the same direction.In addition,the method can improve the bandwidth of the wavenumber spectrum and enhances the spatial resolution of multistatic SAR image.4.This thesis proposes a high-resolution imaging method based on nonuniform sampling data reconstruction for multistatic SAR.The method reconstructs the target profiles along different directions by Radon transformation and generalized iterative adaptive approach,which can be applied to solve multistatic SAR high-resolution imaging problem of discontinuous apertures with different directions.The above model and the proposed methods for multistatic SAR are verified by simulation results,which can achieve the high-resolution imaging in different configurations of multistatic SAR.