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2007
Conference Paper
Titel
The double sliding spotlight mode for bistatic SAR
Abstract
In the case of hybrid bistatic SAR constellations where the transmitter is mounted on a satellite and the receiver on an airplane (or the other way around) one has to face a huge discrepancy between platform velocities. Since this large difference prohibits a temporal steady state, novel non-stationary operation modes have to be investigated. One interesting mode is the 'sliding spotlight' where the antenna footprint moves at a different velocity than that of the platform according to a sliding factor. For monostatic operation a trade-off between azimuth resolution and scene extent in azimuth can be adjusted by variation of this factor. In bistatic constellations, however, also the system mounted on the airplane can utilize beam steering. The airborne system may be operated also in a sliding mode with a sliding factor which can be quite different from that of the satellite. This special mode is called 'double sliding spotlight mode'. The aim of this paper is to illuminate the dependencies of resolution and scene extent on the choice of the sliding factors. In contrast to the monostatic SAR, it turns out, that the resulting bistatic SAR image can be divided into five sections with different azimuth resolutions; only the central zone provides the finest resolution. In part, this is due to the longest illumination time the extent of which is derived in detail.
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