Research On High Resolution Imaging Technology Of Sar In Near Space

Along with the development of applications in radar detection imaging and the increasing demand, the space resources of the troposphere and satellite orbit increasingly are scarce. So, near space as broad space between them has been paid more and more attention in recent years.In the field of radar imaging, combined with the characteristics and advantages of near space platform and synthetic aperture, near space SAR radar has more superior performance and stronger flexibility than satellite-borne SAR and the airborne SAR in many respects including detection precision, staying time in the sky, covering areas, and detection range etc. So it has become an important supplement for the airborne SAR the space-borne SAR. High resolution SAR not only can be used for topographic surveying and mapping, geological prospecting, Marine research target imaging, it also can be uses in the target detection in complex environment, so high resolution imaging technology of near space SAR has certain theory and application value.In this thesis, high resolution imaging technology of near space SAR has been carried on the in-depth research and analysis. First, near space SAR’s characteristics, the imaging principle, and the imaging methods are discussed. And the imaging modeling of the spotlight SAR in near space and high resolution imaging algorithm are this thesis’s research priorities. To solve the problems of spotlight SAR in near space including high space position, overlong synthetic aperture, limit of power and pulse repetition frequency, this thesis puts forward an improved algorithm—Range Migration Subaperture Algorithm. Finally, the advantages of improving the resolution of RMSA is verified through the simulation.The main innovation points include:(1) According to the properties of the imaging platform in near space, the modeling of spotlight SAR in near space is established. The unique position of near space SAR makes it different from airborne and space-borne and it’s the unique environment and vehicle designs have influences up on resolution. The near space SAR platform has gotten further analysis and research, and provides a modeling for high resolution imaging of SAR in near space.(2)A new algorithm, Range Migration Subaperture Algorithm is proposed based on aperture division and RMA. The algorithm is applicable to the spotlight SAR imaging mode in near space. It can reduce the limitation of Pulse Repetition Frequency (PRF) and radar power, and solve the problems of Spotlight SAR in near space such as overlong synthetic aperture, motion error, etc.