Hybrid strip-map/spotlight SAR

Abstract

In this paper the relationship between the two normal operating modes of Synthetic Aperture Radar (SAR), strip map and spotlight, is established mathematically. In this way a more general description of SAR imaging is presented where the strip map and spotlight modes are shown to be limiting cases. The insight that this description offers leads directly to a very simple means of optimising the resolution and coverage area requirements for any desired imaging application, particularly when it is advantageous to increase the coverage in spotlight mode beyond that offered by the real beamwidth. In a practical system this does not necessarily provide a trouble free route to properly focussed distortion free imagery and care has to taken to remove the effects of severe range cell migration. Techniques to overcome these and other effects are discussed together with the processing limitations subsequently imposed. >