On the stability of large antennas as calibration targets

Large radar cross section (RCS) and high temporal stability are the typical requirements expressed nowadays to external calibration targets to be used for spaceborne SAR calibration. The use of ground-based large parabolic reflector antennas may be a good alternative to active radar calibrators or corner reflectors. Outstanding stability of the antennas RCS was demonstrated in a calibration series under AO3-343 in 1999-2000. Under the extension of the project in 2002 with a goal of preparation to ENVISAT mission we were able to demonstrate the repeatability of the series of observations made before as well as our ability to control polarisation of backscattered signal and to show phase stability of the backscatter, what is important for repeated orbits interferometry.