基线是干涉SAR工作原理中的关键概念。它反映干涉测高原理的本质，既是相干性的来源，也是导致基线干损的根源，它还用极限基线给出了干涉存在的条件。本文详细分析了基线、基线干损、极限基线，以及它们之间的关系，并引入新一个的概念；相干角，来更加准确和深入地分析上述关系，指出了它们在频域和图像域中的表现。

Baseline is a significant concept in the principle of SAR Interferometry. It reflects the inherent characters in the height measuring of InSAR, because it is not only the source of coherence but also the root of baseline decorrelation, and it defines the limitation of InSAR by a critical baseline. In this article, the baseline, the baseline decorrelation, the critical baseline and the relationships among them were analyzed thoroughly. A new concept, named coherent angle, was introduced to make the analysis more precise. The appearances of them both in time domain and image field were also explained.

TN958