Absolute radiometric calibration of the novel DLR “Kalibri” transponder

The technological advancement of the synthetic aperture radar (SAR) principle leads to an innovative challenge for the calibration as well. In order to provide an active reference target for an accurate absolute radiometric calibration the knowledge of the target´s backscattering characteristics is essential. For the recently developed DLR C-band transponder named “Kalibri” several strategies for an accurate determination of the radar cross section (RCS) have been analyzed. Based on a comparison with respect to accuracy and feasibility, several recommendations for the best transponder calibration strategy were established. The resulting RCS of the transponders retrieved from the most suitable measurement method is presented as well as a cross-validation to prove the plausibility of these results.