Development of DLR's Next Generation C-band Calibration Transponders for future SAR Missions

Abstract

Modern spaceborne Synthetic Aperture Radar (SAR) systems used for Earth observation are capable of acquiring high-resolution data. To ensure high quality data, the SAR system must first be calibrated. DLR’s SAR Calibration Center has been involved in the calibration of various spaceborne SAR missions for more than 25 years. A key activity is the development, production and operation of suitable calibration transponders for different frequency bands. Since the launch of ESA’s first Sentinel-1 satellite in 2014, six remote-controlled reference targets (three corner reflectors and three transponders) located in southern Germany have been successfully operated for more than 10 years. The three transponders, referred to as “Kalibri” transponders, weredeveloped and manufactured entirely in-house. in accordance with the requirements applicable prior to 2014. In order to be well prepared for future Cband SAR missions (e.g. Sentinel-1 Next Generation) and to guarantee a central calibration site including calibration support until the end of the Sentinel-1 mission, DLR has already started the development phase for the next generation of C-band transponders. This presentation will outline the current status of DLR’s C-band transponder development and present the planned upgrade in more detail.