Passive geosynchronous SAR system reusing backscattered digital audio broadcasting signals

A synthetic aperture radar is considered, located on a geosynchronous receiver and illuminated by the backscattered energy of satellite broadcast digital audio or television signals. The principal application of such a passive system could be differential interferometry, since even low spatial resolution coupled to zero baseline would be useful; however, other imaging applications could be envisaged and even some topographic capabilities if a baseline is created by ellipticizing the receiver’s orbit. Spatial resolution, link budget and possible focusing techniques are evaluated.