The Cost of Opportunity for Gapless Imaging

Utilizing digital multi-channel technology, spacebome synthetic aperture radar instruments are capable of imaging swath widths of hundreds of kilometers at fine azimuth resolution. The main benefit follows through the extension of the trade space and the use of new digital beam-forming techniques facilitated through the multi-channel instrument architecture. This is truly a quantum leap as the performance of these systems will be orders of magnitude better than current in-orbit and state-of-the art systems. One of the basic restrictions applicable to spaceborne platforms hosting both the transmitter and receiver is the "blinding" of the receiver during the transmit time instances, which manifests itself through imaging gaps. One of the main challenges the instrument designers are faced with, is to circumvent these gaps, requiring the use of dedicated instrument operation modes. An alternative approach is multi-beam imaging, i.e. to allow the gaps in the single SAR acquisition, while using an appropriate mission design for filling the blind gaps. This paper explores the trade space options for high-resolution wide-swath SAR imaging. The comparison of multi-beam and gapless imaging from an instrument design and performance point of view is elaborated.