Application Research Of SAR Imaging Based On A UWB Radar Sensor

The accuracy of target information is determined by radar image resolution.By mounting on a mobile platform,synthetic aperture radar(SAR)extends the antenna beam width and achieves the high azimuth image resolution.Owing to the ultra-spectrum signal,ultra wide band(UWB)radar sensor has the advantage of strong penetration and high range resolution imaging.Therefore,the new imaging system which combines the SAR imaging technology and UWB radar sensor can obatin the high resolution images of targets,and has a significant research value in extensive fields,such as environmental investigation and space monitoring.This thesis study the application of a high spatial resolution(cm level)rail SAR imaging system based on a UWB radar sensor,aiming at three key issues: system design,imaging methods and experiments.According to the sufficient one-dimensional(1D)radar range profiles at different locations,the basic research of two-dimensional(2D)and three-dimensional(3D)SAR imaging are carried out.The specific contents of our work are summarized as follows:1.In order to design the UWB SAR imaging system,we analyze the basic structure of pulsed-type UWB radar sensor,and select rail SAR as the system imaging scheme.Then we compare the time-frequency characteristics of three kinds of Gaussian type UWB signals by simulation results,and discuss the structural design of quasi-horn and planar UWB antennas.Consequently,the selection criteria of equipments studied by this thesis is established.2.As for the UWB SAR imaging method,we firstly model the SAR echo based on a UWB radar sensor.With the consideration of the non-ideal situations,three kinds of pre-processing methods are analyzed.Then we study the UWB SAR imaging algorithms for the rail SAR imaging system,and obatin the 2D simulation results under the condition of system parameters.3.In the environment of semi-open microwave laboratory,we study the small linearrail SAR imaging system,and use a pair of directional broadband planar UWB antennas to replace the original omni-directional dipole UWB antennas.The measured data of UWB signals demonstrate that the planar UWB antenna can effectively alleviate the coupling noise.4.In the imaging experiments of 2D UWB SAR,we use the time domain correlation(TDC)and range Doppler(RD)imaging algorithms to obtain centimeter level high-resolution UWB SAR images of aluminum soda cans.In addition,due to the fact that the 2D UWB SAR images exist the distortion problem in the altitude direction,we conduct the 3D UWB SAR experiments,and use the back projection(BP)and RD algorithms to reconstruct the 3D UWB SAR images of a corner reflector and metal ball.The results verify the feasibility of 3D SAR imaging in the rail SAR system studied by this thesis.