Digital beamforming and MIMO SAR: Review and new concepts

Spaceborne Synthetic Aperture Radar (SAR) is a unique tool for large scale Earth observation, but the current generation of SAR sensors suffers from some fundamental limitations with regard to their imaging and mapping capabilities. To overcome these limitations, several new instrument architectures and SAR imaging modes have been suggested that employ digital beamforming (DBF), multiple aperture data recording and MIMO SAR techniques. This paper provides a critical review of these techniques and makes some suggestions for further improvements. Special attention is given to advanced DBF and MIMO SAR concepts for ultra-wide swath imaging.