The study background of the low frequency uwb - sar is given in chapter 1 . the sar calibration hierarchy model is proposed , and the calibration concepts and strategies are discussed clearly 第一章分析了低頻uwb - sar的研究背景,提出了一種sar層次化校準(zhǔn)模型,較為清晰地論述了sar校準(zhǔn)概念和策略。