| Synthetic Aperture Radar (SAR) is the high science and technology radar that can take high resolution imaging for the ground target by using the synthetic apertureprinciple and pulse compression technique. Sines the terrain, time, weather don't affect it, SAR has been widely applied in the areas of military and civil and it has brought great benefits in economics and society. With the technology evolution and the application extension, people desire to get high quality SAR imaging, not only get the high resolution two-dimensional image of the ground immobile targets and moving targets, but also get the three-dimensional image of them. In military, we hope to get not only high resolution the side-looking SAR imaging but also high resolution the squint SAR and the forward-looking SAR imaging with oneself security and agility, and request not only the single antenna (single satellite), single mode high resolution imaging but also multiple antennas (multiple satellites), multiple modes high resolution imaging, because they can reduce cost, get multiple high resolution images of the same area, and enhance the security of the SAR plate. This dissertation is based on the subject "The Study on the Forward-Looking SAR Imaging of the Cluster Satellite SAR System"; the subject belongs to the subject "The General Technology Argumentation of the Cluster Satellite SAR System". Sine the squint SAR and the forward-looking SAR are different and relative, and they have the security, the agility and the advantage in the application, and they are a development aspect of the SAR imaging, it is necessary to research them thoroughly.The Dissertation thoroughly studies the squint and forward-looking SAR imaging; the main contents of it are as follows: To the squint SAR working-mode, the dissertation carefully analyses the properties of the squint SAR system, including the Doppler characteristics of the target, azimuth resolution characteristic, the platform attitude effect on the squint SAR and how to choose pulse repeat frequency etc. Sine the range migration in the squint SAR is bigger than range migration of the SAR imaging and destroys the imaging quality, the paper discusses in detail the effect of range migration on the phase precision, and indicates that the range equation should use high-order Taylor approximate in the squint SAR in order to achieve high precision imaging for the targets. In spaceborne SAR, the dissertation analyzes the difference of the Doppler by the Earth rotation and beam squint, and discusses their effect on range migration and1. the way of correct range migration in range-Doppler domain. 2. The range-Doppler (RD) algorithm is the conventional imaging algorithm for the side looking SAR. Due to greater range migration, the RD algorithm itself has deficiency for squint SAR, based on the conventional RD, the dissertation carefully discusses second range compression (SRC) algorithm, squint imaging mode (SIM), and puts forward an extended RD (ERD) algorithm for squint SAR, and completes point target simulation using RD, SRC, SIM and ERD, and compares the advantage and defect of these algorithm, then carries raw data imaging using SRC and gets target image. 3. To the squint SAR working-mode, the dissertation establishes the echo model of the radar signal using the squint range equation, and carefully analyses the instantaneous azimuth frequency and instantaneous Doppler frequency and the effect of range chirp on azimuth frequency by coupling between the range and azimuth signal, and brings the accurate expression to calculate the instantaneous Doppler frequency. Then to combine the general CS algorithm, the paper proposes the improved CS algorithm for squint SAR imaging and the nonlinear CS algorithm for forward-squint SAR imaging by inducing 3rd, 4th term and line frequency modulate rate approximation of the echo in 2D frequency domain, and accomplishes the point target and raw data imaging using the two algorithms, gains high quality target images. 4. SAR imaging is a 2-D...
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