Illumination Constraints for Forward-Looking Radar Receivers in Bistatic SAR Geometries

The use of bistatic geometries in radar applications offers new ways in passive imaging for forward-looking receivers. Besides the challenges in synchronisation between transmitter and receiver constraints in illumination come to the fore. In configurations in which the receiver is triggered by direct signals this can strongly reduce the length of the synthetic aperture and therefore diminish the resolution in azimuth of recorded SAR data. In this paper formulas for the so called dasiaeffective synthetic aperturepsila and the dasiacritical bistaticpsila angle are derived. Afterwards both results are illustrated by radar data recorded in a bistatic field campaign by a forward-looking receiver unit.