SAR interferometry

The institute has worked with various aspects of interferometric SAR systems since 1993. The SAR installation on the Danish Air Force Gulfstream aircraft includes two fixed (not steerable) C-band antennas mounted with a 1.14 m across-track separation and one three axes stabilised C- or alternatively L-band pod-antenna. The SAR is thus capable of acquiring C-band interferometric data with a well-known baseline from a single flight track (single pass across-track interferometry, XTI) and simultaneously L-band polarimetric data from the pod-antenna. A unique servo system for controlling the aircraft flight path to within a few meters from the navigation reference, provides a basis for repeat track interferometric measurements.
In 1996 the fixed (XTI) polarimetric antennas were measured in the radio anechoic chamber at EMI. It was confirmed that the radomes have an insignificant influence on the antenna patterns.
Several XTI data sets have been acquired by the EMISAR from four different missions in 1996. Data from Råbjerg Mile and the Research Center Foulum have been processed and calibrated to high resolution digital elevation maps with an elevation resolution of better than 1 m.
In 1997 the study of calibration aspects of EMISAR XTI data was continued, with the aim of finding robust methods for calibrating the system for inaccurate navigation data and system parameters as well as system imperfections like multi-path effects.
During all EMISAR campaigns XTI data were acquired. Experiments with mosaick-ing XTI data were initiated. For example a 25 km by 60 km area of the Geikie Plateau was covered with three adjacent strips and a 50 km by 150 km area of Island was covered with five adjacent strips. (Related projects - see: www.dcrs.dtu.dk).