Differential SAR interferometry using corner reflectors

The differential InSAR technique has the potential for monitoring centimetre-scale ground motion in an accurate and cost-effective manner. Probably the most important limiting factor in the application of InSAR is temporal change in the complex reflectivity of the ground surface during the period between radar acquisitions. This can be due to changes in such parameters as moisture content or vegetation. The stable artificial corner reflectors can be identified from long temporal series of interferometric SAR images even with large baselines and therefore decrease the risk of image decorrelation. In this paper we will discuss the following questions: (1) how to get the true phase of a corner reflector in a SAR complex image; (2) how to co-register the corner reflector pixels, if the coherence of its surrounding area is extremely low; (3) how to computer the interferometric phase of two co-registered corner reflectors without flat Earth term and corners´ height contribution. In order to demonstrate the results some practical examples Bonn-Experiment and landslide monitoring in Three Gorges area in China are given.