SAR/ISAR imaging in passive radars

This paper presents a study on the possibility of using Synthetic Aperture Radar (SAR) and Inverse SAR (ISAR) imaging techniques in passive radars, utilizing commercial continuous wave transmitters as illuminators of opportunity. In presenting potential applications of this novel technology, obtainable maximum ranges and resolutions in passive SAR/ISAR technology are discussed. In the paper the main stages of a signal processing chain for SAR/ISAR imaging in passive radar are presented and discussed, showing the challenges and limitations which have to be addressed in designing the passive SAR/ISAR system. Additionally, real SAR and ISAR images obtained by passive radar demonstrators utilizing Digital Video Broadcasting-Terrestrial (DVB-T) illuminators are presented as the proof of concept of the presented technology.