Research Of Circular Sar Three-dimensional Imaging Algorithm Based On Wavenumber Domain

The trajectory of the radar platform in traditional linear SAR is a straight line, so that the spatial domain spectrum of the target scene after imaging is limited to be the fan. But the circular SAR(CSAR) is a new three-dimensional SAR imaging system, whose radar platform moves in an uniform circular motion around the center of the ground targets at a certain height. Due to its special movement, it can not only realize the goal of three-dimensional imaging, but will also expand the spatial domain spectrum into a hollow circle, which can improve the imaging resolution. Basing on the above advantages, circular SAR has been widely used in the vegetation detection, military, meteorology and crops and so on. Therefore, more and more researchers begin to pay close attention to circular SAR research.In this dissertation we mainly study the relevant theories and imaging algorithms of circular SAR. It will verify the feasibility of the algorithm by setting the target scene, and enrich the theory of circular SAR three-dimensional imaging system. The main contributions are presented as follows:(1) We establish the geometric model of circular SAR system and simulate target signal echo. Apart from that, we demonstrate the height resolution of the circular SAR intuitively and theoretically; with the help of fuzzy function, we deduce the level resolution and high resolution formula of the circular SAR, and analyze the factors that will affect the size of its resolution, it will lay a theoretical foundation for the subsequent wavenumber domain imaging algorithm.(2) By means of fourier transform, we introduce of the concept of wavenumber domain. Firstly we present the overall framework of algorithm, then put the echo data obtained from the receiver on the ground plane for 2 d imaging, we multiply the corresponding height factors of each point on different surfaces, and obtain the 2 d imaging results of each height level surface, lastly we can use the slice technology to realize three-dimensional imaging.(3) We use the above algorithm to simulate the three target scenes respectively, and obtain the target imaging results. It not only demonstrate the feasibility of the proposed algorithm, but also the ability of the height resolution of circular SAR. We analyze spatial spectral of imaging results, the other hand, we carry out research on side lobe suppression by simulation.In short, this dissertation analyzes the circular SAR three-dimensional imaging algorithm, and verify the feasibility of the algorithm by the simulation of target imaging.