The Sentinel-1 C&D SAR Instrument

Sentinel-1 C&D SAR instruments are designed to continue the observations beyond the lifetime of Sentinel-1 A & B. They are to a high degree rebuilds of S-1A&B and will have the same imaging modes and interfaces to ground. Changes have been implemented within the SAR antenna by using a new Tile Amplifier design, which will contribute to improved radiometric stability and accuracy. The new tile amplifiers simplify the internal calibration approach by reducing the number of internal measurements from five to three. Another improvement is the introduction of interleaved noise measurements during image acquisition in addition to noise acquisitions in preamble and postamble. This is important as the surface brightness temperatures have a significant impact on the acquired noise and can change the measured noise levels by up to 1 dB. A first tile for S-1C with the new design has been successful tested. Results confirm the updated design and indicate improved measurement accuracy.