DInSAR deformation measurement using active and passive reflectors

Passive Corner Reflectors (PCR) are often used in spaceborne SAR interferometry as benchmarks. The main goal of the use of PCRs in DInSAR deformation monitoring is to provide pixels with a high and stable response to be used as reference to estimate the deformation when natural persistent scatters are not available. The use of PCRs at C band is not always suitable, especially in areas as glaciers, snow covered regions, and mountain slopes, where accessibility and PCRs' installation can be very time and cost consuming, or where harsh weather conditions can jeopardize their performance. An alternative to PCRs is Active Reflectors (AR), more compact and lighter apparatus, which need a power source, and are often susceptible to the natural air temperature variations which can affect the stability of their response. The study presented here reports on the use of an AR designed to operate with Sentinel-1 SAR data, installed with some PCRs aimed at comparing the performance of the two approaches. The AR was designed and implemented to provide a fair performance/cost benefit to make feasible the setup of a dense network. Images covering almost one year have been processed to compare the performance of a prototype installed close to our center. A real campaign was also carried out installing an AR together with a network of PCRs in a site, located in a mountain area of Andorra, where a landslide occurred in 2018, and where a monitoring based on DInSAR is ongoing