Continuous Wave Synthetic Aperture Radar Imaging Technology Research

Frequency modulated continuous wave(FM-CW) synthetic aperture radar(SAR) is a new kind of high resolution radar, which not only has the high resolution ability under all weather,day and night, but also has the advantages of compactness and cost-effectiveness. Therefore, it is of high value in both military and civil applications.However, because FM-CW SAR is a radar of frequency modulated continuous wave, its frequency sweep period, usually 1 to 10 ms, is much longer than that of tranditional pulsed SAR, which is measured byμs . The long frequency sweep period detoriates distortions of received pulses of FM-CW SAR, which makes the"stop-go-stop"assumption not suitable for FM-CW SAR any more, so the tranditional imaging algorithms based on the assumption can not simply applied to FM-CW SAR. This paper derived the particular signal model based on the dechirped raw data of FM-CW SAR, and then modified the tranditional Frequency Scaling algorithm(FSA).In the introduction to this dissertation, the research significations, development and advantages of FM-CW SAR are reviewed. The main contribution of the dissertation is also summarized.In chapter 2, the principles of high resolution and imaging of FM-CW SAR are introduced.In chapter 3, signal model of FM-CW SAR is derived on the basis of the analysis of dechirp technology and its resolution.In chapter 4, tranditional FSA is studied and modified based on the special FM-CW SAR signal. Simulation results of tranditional FSA and modified FSA applied to FM-CW SAR are derived ,compared and analysized, which proves the validaty of the modified FSA.In chapter 5, the principle of Chirp Transform(CT) is introduced and used to modified the modified FSA for high-squint case. Simulation results and data analysis are also presented here, which proves the validaty of CT algorithm in high-squint case.In the end, conclusions are made.