Technology developments for the next generation of spaceborne SAR instruments based on digital beamforming

During the past ten years a number of research groups around the world have been investigating the use of digital beamforming for spaceborne SAR instruments. The separate optimization of the effective transmit and receive aperture sizes together with the splitting of the receive side into multiple receive sub-apertures which can be combined on board by means of digital beamforming allows for a number of new SAR modes. With this it is for example possible to overcome the principle swath width and azimuth resolution limitation known in classical SAR instrument designs. ESA has performed and initiated a number of systems studies to identify the critical technologies needed for this type of instrument. Based on these system studies a number of technology development activities have been started. This paper gives an overview on the studies and technology developments performed in this context.