| Synthetic aperture imaging processing and ground slowly moving target detection technology are the key points to improve the performance of the air to surface operation mode for airborne radar. The higher is the requirements for the performance of air to surface mode, the deeper study in the field is needed . This is the main purpose to this dissertation.With the concept of array antenna and the analysis of the Doppler frequency character of the signal received by radar, the principle of SAR is simply presented in Chapter 2. The focused SAR is compared with real beam map and non-focused SAR. The couple relationship of received signal between range dimension and azimuth dimension is verified. The couple will become stronger when the resolution is higher, the center frequency is lower and the radar range is further. So there are many imaging algorithms used for different cases.Based on four models of signal from a point target, Chapter 3 deals with main imaging algorithms available to form uniform theoretical basis. It is clear from the analysis that although the processing in detail and compensation precision of these imaging algorithms are different, all algorithms base on the analysis of received signal in two frequency dimensions. The higher the compensation precision, the better the image quality and the wider the application.The special relationship among signal bandwidth, center frequency and imaging squint angle in the Range-Doppler imaging algorithm and other methods is also presented in the Chapter 3. The relationship shows that the maximum bandwidth is limited for these algorithms and becomes narrow when the center frequency is lower and the imaging squint angle is larger. These conclusions are important for choosing suitable radar system parameters such as center frequency , resolution and imaging squint angle in engineering design.In the last ,the Chapter proposes a new wide band imaging algorithm. The maximum bandwidth of the algorithm is larger for broadside looking or small imaging angle. At same time, interpolation is not needed for the algorithm, therefore the computation efficiency is high. The imaging algorithm provides a new choice for wide band imaging.According to the SAR radar performance such as resolution, the choice and requirement for radar system parameters are discussed in the Chapter 4. Specially theprecision requirement of velocity, acceleration, and the roll, pitch angle and altitude of radar carrier provided by INS is deduced in detail. Finally several common auto-focus imaging algorithms are discussed.These results can be directly used for SAR radar design. A important conclusion is verified from these analysis that although the azimuth resolution of SAR radar is theoretically not connected with parameters such as radar range and center frequency, in fact, on the condition of same resolution, when the range becomes further and center frequency become lower, the requirement for the radar power gain production, signal processing and precision of INS will be higher, therefore the imaging will become more difficult . So great effort should be needed on the analysis and selection of parameters of SAR radar and its related equipment for good radar images.For a long time, it is a big problem for radar to detect and relocate the slowly moving target in the main lobe clutter. Based on the references available, the principle of moving target detection and relocation of a three-port interferometer is analyzed in Chapter 5. It modifies the view in these references that two-port interferometer can be used to detect and relocate moving target. The influence of factors existing in the radar system on the detection performance is discussed . These conclusions are also verified by computer simulation.From the analysis and simulation , it can be seen that with the method, the detection performance of slowly moving target in the main lobe clutter area will be largely improved with the condition of engineering errors. The method is simple in construct and adaptive to ra...
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