Research On Satellite Target 3D Imaging Technology At Terahertz Frequencies

Terahertz radar is a new type of radar system that can obtain higher resolution than conventional frequency bands.Curved SAR is an ideal imaging system,with full-angle observation,radar video imaging and three-dimensional imaging capabilities,and its special motion trajectory just fits the spatial observation trajectory,which has important research significance.This article focuses on the three-dimensional imaging technology of terahertz radar curve SAR,and carries out the following research on the imaging theory,echo modeling,imaging algorithm and other contents involved:1.The system characteristics of Circular SAR(Circular SAR,CSAR)are studied,including imaging geometry,echo modeling,spectrum support area,point spread function,etc.And a detailed study of single-pass CSAR and multi-pass CSAR is conducted,In combination with the spherical wave decomposition technology,a fast imaging algorithm in the frequency domain is given to lay a theoretical foundation for subsequent research.2.Based on the satellite target trajectory,the Spiral SAR(Spiral SAR,SSAR)imaging geometry and echo model are established,the distance history and echo model are derived,and the resolution is analyzed to provide theoretical guidance for SSAR imaging.3.The feasibility of SSAR three-dimensional imaging is analyzed,and the SSAR time-domain imaging algorithm is studied.The signal processing flow and the point expansion function of the SSAR system are given,which provides a direct method for SSAR imaging Technical approach.4.Aiming at the defects of large calculation amount and low operation efficiency of SSAR time-domain imaging algorithm,try to develop SSAR frequency-domain imaging algorithm.Firstly,the polar coordinate format algorithm is derived,which obviously improves the imaging efficiency of the target in a small imaging area.Then,a frequency domain compensation algorithm based on a cylindrical array is studied,which expands the effective imaging range.Finally,simulation experiments verify the effectiveness of the proposed algorithm.