The Methods And Experiment Application For SAR Imaging Of Two Kinds Of Wideband Radar

Synthetic Aperture Radar (SAR) is a kind of active microwave imaging radar. It can work under all-weather and all-day conditions, having high resolution and good penetrability into vegetation and ground. Hence, it has been widely used and developed in military and civil fields. The methods and realization for SAR imaging of two commonly used wideband radar systems, i.e. Linear Frequency Modulation (LFM) and Stepped Frequency (SF), are systematically studied in this paper. In addition, experiments are carried out to validate the methods. The main contents are summarized as follows:Chapter 1 introduces the current status and trends of the technique for SAR imaging in combination with the background and significance of the subject. Also, it summarizes the main work done in this paper.Chapter 2 studies mainly the technique for high resolution imaging in the range dimension. Firstly, the model of targets'echoes of LFM radar system is constructed, and the two methods for range profiling, i.e. pulse compression and dechirp, are analyzed particularly combining the model. Then the model of targets'echoes of SF radar system is constructed, and the two methods for range profiling, i.e. IFFT synthesis and bandwidth synthesis, are introduced. Based on this, an improved method of bandwidth synthesis is proposed. The efficiency of the method is validated by simulation results.Chapter 3 studies the problem of SAR imaging of LFM radar system. First, the principle of high resolution in the azimuth dimension is analyzed. Then the two methods which are basic R-D and R-D with SPECAN of SAR imaging are studied, and SAR imaging of point target using the methods are simulated. Finally, SAR imaging of a port area is accomplished using the algorithm of R-D with SPECAN in the experiment of LFM radar system carried by car, and the test results verify the effectiveness of the algorithm.Chapter 4 studies the problem of SAR imaging of SF radar system. First, differences between SAR systems of LFM radar and SF radar are analyzed, and the problem of parameters design of SF radar is studied. Then velocity compensation method and SAR imaging flow under side-looking mode are introduced, and the effectiveness of the algorithm is demonstrated via simulation and external field test. Finally, velocity compensation algorithm based on RADON transform and SAR imaging procedure with auto-focus algorithm under squint mode are introduced. In addition, images of the test field are obtained using those methods.Chapter 5 summarizes the thesis and points out the future work.