High-resolution Three-dimensional Synthetic Aperture Radar Imaging Technique

High-resolution Three-dimensional Synthetic Aperture Radar (3D-SAR) imaging technique is an important development of the highly developed Synthetic Aperture Radar (SAR) technique. Besides the all-weather and all-time observation capability, the high-resolution 3D-SAR imaging technique particularly allows the mapping of complicated scenes in three dimensions with high resolution. For great application values of civilian and military such as land surveying, oceanography, reconnaissance and surveillance, resource exploration and disaster relief, the high-resolution 3D-SAR imaging technique has already become a worldwide hot topic in the SAR imaging field.For the imaging geometries of the side-looking and downward-looking, this dissertation has made an in-depth research on the high-resolution 3D-SAR imaging technique. Firstly, we discuss the imaging techniques of the side-looking spotlight SAR and Interferometric SAR (InSAR), and describe the solution of the layover problem by using the multi-baseline InSAR technique. Based on a thorough analysis of the previous works, we use the spectral analysis technique to avoid the azimuth ambiguity effect and the subsegment-division weighting approach to overcome the azimuth sidelobe suppression problem, which can generate spaceborne sliding spotlight SAR images of high quality. In the following, the downward-looking high-resolution 3D-SAR imaging technique is discussed, which can mitigate the layover and shadow effects significantly. After the detailed analysis of the downward-looking high-resolution 3D-SAR imaging technique, we propose two schemes for the system design. The innovative work of the two schemes lies in the realization way of the third dimension distinguishing ability. One is that we optimize the distribution of the sparse array elements to decrease the element number and thus reduce the amount of the resulting data. With the optimized sparse array, the resolution in across-track direction is realized by using the Capon beamforming technique; The other is based on the transmit beamforming technique, namely the resolution in across-track direction is realized by narrow transmit beam scanning. With the designed single receiver antenna, the hardware cost for receivers is reduced to a minimum. Therefore, the amount of the resulting data is effectively decreased and the imaging processing complexity is greatly reduced. Finally, a summary is given and some research proposals are provided.