Earth observation instruments with e-scan antennas state-of-the-art and outlook

Spaceborne radars with electronically scanned antennas are in use on European satellites since the launch of Envisat in March 2002. Despite the higher complexity and consequently cost, electronically scanned antennas are more and more attractive for spaceborne radar. The return materialises either in significantly better system performance or in newly gained system feasibility. The paper will discuss firstly state-of-the-art phased array technology as used for the European Sentinel 1 C-band SAR and explore secondly the capabilities of full digital beam forming implementation for the next generation of SAR systems. Thirdly phased arrays as a feasibility prerequisite in quasi bi-static radar for future ocean altimetry, exploiting GNSS signals will be discussed. Lastly reflector based e-scan antennas will be discussed which form a good compromise between complexity and flexibility as needed for SAR systems requiring high gain antennas. A Ka-band SAR application will be presented.