| Monostatic synthetic aperture radar (SAR) could perform two-dimensional (2D) and high-resolution imaging for the area in its side direction, and has been widely applied in both the military and civil fields. However, it can not achieve 2D imaging because of the same direction of range and azimuth resolutions in forward-looking mode. Through adding one platform, we can get such a configuration in which the transmitter works in side or squint looking mode, and the receiver in forward looking one. In this case, there exists a certain angle between range and azimuth resolutions, and enough Doppler bandwidth can be synthesized through the motion of platforms, which redounds to realize 2D imaging in forward-looking mode. High-speed maneuvering-platform SAR is an important application of SAR imaging technology. It is of significant importance for maneuvering-platform to obtain such information of those targets in the straight-ahead position during terminal diving period, especially when attacking the key parts of such targets in complex background as aircraft carrier and warship groups. There are usually serried warships in complex distributing background including both ocean and land. Among terminal guidance means in monostatic SAR platforms, those ways such as angle measurement through mono pulse radar, SAR imaging through squint/forward looking mode could not perform 2D imaging with high resolution during the whole terminal diving period, and thus it is difficult to distinguish targets in complex background using such these ways.Bistatic forward-looking high-speed maneuvering-platform SAR (BFHM-SAR) is a new imaging mode, which is the application of bistatic forward-looking synthetic aperture radar to high-speed maneuvering-platform. It contains such advantage of bistatic forward-looking SAR and could perform 2D forward imaging through moving trajectories appropriately during the whole terminal diving period of missile. However, there are high velocities and accelerations in both transmitter and receiver owing to the combination of bistatic forward-looking and high-speed platform. There will be some new motion features in this configuration compared with traditional airborne monostatic or bistatic SAR imaging mods, in addtion to the characteristics of high speed, great maneuverability and long distance in high-speed platform. In this dissertation, system characteristics, motion features and imaging algorithms corresponding to bistatic forward-looking SAR in high-speed maneuvering platform.The main content of the dissertation is summarized as follows.1. Study on imaging theory and system features of a certain configuration has great influence on the subsequent designing imaging algorithms and system parameters. Firstly, we discuss the 2D space variance compared with the space variance in range direction. Such parameters as range walk ratio (RWR), Doppler centroid and Doppler rate are analyzed and simulated considering different azimuth locations, different trajectory included angles. Then, range and azimuth resolutions are calculated using gradient method and K-space method. The approximation error of gradient method is obtained through comparing the difference of these two calculation ways, and finally adoption of gradient method in this configuration is confirmed.2. It is very important to design spatial geometry configuration of BFHM-SAR due to the fact that imaging results of this configuration has great deal with motions of transmitter and receiver. To form such bistatic forward-looking imaging mode that could provide the results meeting resolution requirement, there needs to design the trajectory of transmitter reasonably according to the default one of receiver. A design method of trajectory based on a linearly attenuating model is developed in this dissertation. The accurate expressions of ground range resolution and azimuth resolution are firstly gained based on gradient method. And then, the whole imaging period is divided into several stages by inputting the default trajectory of the receiver. Initialize the trajectory parameters or adjust attenuating step based on calculated resolutions in each stage, until the end of the imaging period. Finally, the validity of the proposed method is testified by simulation experiments。3. Raw data simulation in complicated configuration is an important tool for algorithm testing. Unlike traditional airborne platform, there are high velocities and accelerations in both transmitter and receiver, and the heights of them are descending gradually in BFHM-SAR configuration. The traditional methods cannot be applied to BFHM-SAR directly owing to the special feature. A fast raw data simulator is developed based on range equivalence and correction of phase space variance in this dissertation. The range history containing both double square roots and high-order terms is firstly equivalent as monostatic one using the revised hyperbolic range equation, followed by which the 2D frequency spectrum is obtained using the principle of stationary phase (POSP). And then azimuth compression term and range migration term with serious space variance are corrected with high-order polynomial fitting. Using SAR image as input, this algorithm can reconstruct raw signal of bistatic forward-looking SAR efficiently in high-speed maneuvering condition. Finally the effectiveness and efficiency of our method is confirmed through scattering target and scene simulations.4. We also discuss 2D coupling and space variance of range/azimuth equivalent chip rate with bistatic slant range in different imaging distances, based on which an imaging method is proposed for extended scenes in BFHM-SAR configuration. The range history is approximated accurately after the linear range walk ratio is corrected, and then 2D frequency spectrum is got by the method of series reversion (MSR). Through quantificational analysis of phase terms which effect imaging focus results significantly, we can conclude that the variance of range equivalent chip rate can be ignored because of its minor change, while the one of azimuth equivalent chip rate should be considered. Concerning this problem, its variance can be corrected by designing space-variant filter. The well-focused results of point and scene targets validate the effectiveness of the developed algorithm. What’s more, we also investigate the influences of motion error and time/frequency synchronization on 2D frequency spectrum and imaging, and reveal the affect patterns of each error component.5. A new method to give on-line amplitude and phase errors correction in varying jamming environment, to deal with such a problem that amplitude-and-phase error between phased array channels could result in amplitude-phase distortions of output signal. This method can obtain accurate estimation of unknown steering vector of the target echo through eigen-decomposition of data matrix after jamming suppression. The on-line amplitude and phase differences between two consecutive weight update periods can be used to update the optimal weight vector and further correct the distortional output signal. Simulations of three different kinds of array models verify the effectiveness and robust characteristic of our method.6. It can form "satellite-airplane" bistatic forward-looking circular SAR three dimensional imaging mode by the combination between the transmitter such as satellite and space station and the receiver such as airplane. We conduct preliminary study on forward-looking three dimensional imaging capability of bistatic forward-looking circular SAR. The accurate resolution expression of point target in arbitrary location of imaging area is obtained using gradient and ambiguity function methods, which can be used to choose optimal resolution area in the imaging area and the optimal motion period of transmitter. Also, main motion and system parameters affecting resolution significantly are designed.
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