Martin Keller received the M.S. degree in geophysics from the University of Karlsruhe, Karlsruhe, Germany, in 2000. Afterward, he joined the Danish Defence Research Establishment in Copenhagen, Denmark, in the frame of the European TMR project (Training and Mobility of Young Researchers). Since 2001, he has been with the German Aerospace Center, Microwaves and Radar Institute, SAR Technology Department, Wessling. He is involved in the preparation and accomplishment of E-SAR measurement campaigns and in the processing of the recorded data.