GEO Spaceborne-Airborne Bistatic Forward-looking SAR Imaging Algorithm

Geosynchronous spaceborne-airborne bistatic forward-looking synthetic aperture radar is a kind of bistatic forward-looking SAR system with GEO-SAR as transmitter and airplane as receiver.It has the advantages of wide range of beam illumination,good concealment,high safety,getting rich feature information and so on.The system has broad application prospects.Compared with the traditional bistatic SAR configuration,It is a new system in the field of synthetic aperture radar,which researched a short time,and there are many problems to be analyzed and solved at present.Therefore,this thesis will research from the configuration of GEO-BFSAR,the establishment of echo model,the analysis of echo characteristics and the designing imaging algorithms.The main studying contents are as follows:(1)The geometric configuration in local coordinate system is established in response to the different motion characteristics of the GEO-SAR transmitter and the airplane receiver,the motion characteristics of GEO-SAR satellite are analyzed,the imaging performance of the geosynchronous spaceborne-airborne bistatic forwardlooking synthetic aperture radar is researched,including the characteristics of twodimensional spatial resolution,forward-looking imageable time and the size of the imageable area,etc.(2)To solve the problem of poor imaging performance caused by the error of echo model under the "stop-and-go" hypothesis,the echo modeling method of the geosynchronous spaceborne-airborne bistatic forward-looking synthetic aperture radar based on error compensation of pulse delay is studied.The error caused by the traditional "stop-and-go" hypothesis of the geosynchronous spaceborne-airborne bistatic forwardlooking configuration is analyzed,and the accuracy echo model is established.Verified accuracy of established echo model based on the time-domain imaging algorithm.The range migration and doppler characteristics of the geosynchronous spaceborne-airborne bistatic forward-looking synthetic aperture radar are analyzed.The two-dimensional space-variance characteristics of geosynchronous spaceborne-airborne bistatic forwardlooking synthetic aperture radar are analyzed,and the laws of two-dimensional space variance are summarized,which provides theoretical support for the research of frequency domain imaging algorithms.(3)A two-dimensional Omega-k imaging algorithm based on spectrum optimization is proposed.the algorithm can cancel the coupling relationship between spatial variables and frequency variables,and obtain the high-precision spectrum model by optimization method.The imaging algorithm can solve the two-dimensional space variance problem caused by this configuration.The final high-precision imaging results are obtained.The above research work and methods have been carefully analyzed and verified by numerical simulation,their accuracy and effectiveness can be guaranteed.