Accession Number : ADP002724

Title :   Propagation Effects in Satellite-Borne Synthetic Aperture Radars,

Corporate Author : SRI INTERNATIONAL MENLO PARK CA

Personal Author(s) : Rino,C. L. ; Gonzalez,V. H.

Report Date : AUG 1983

Pagination or Media Count : 12

Abstract : Satellite-borne synthetic aperture radars (SAR), such as SEASAT, can map large segments of the earth's surface with a resolution better than 10 m. This high resolution is achieved by processing data coherently from a 10-to-20-km path along the satellite orbit. SEASAT operates at L band, where severe, naturally occurring propagation disturbances are rare except near the geomagnetic equator. On the other hand, because of the large aperture involved, loss of spatial coherence of phase can occur even when no significant amplitude scintillation is present. We have made computations that model the distortion of a point target for typical high-altitude scintillation conditions. The results show that severe degradation of reconstructed SAR images can occur, on occasion, from natural ionospheric disturbances. To confirm these results we have searched the SEASAT data base for obvious examples of the kind of distortion we expected. Several examples were found. Through a fortunate coincidence, incoherent-scatter radar data were available in which we were able to identify the likely source region of one of the disturbances. (Author)

Descriptors :   *Synthetic aperture radar, *Scientific satellites, *Radar mapping, *Ionospheric disturbances, *Scintillation, *Incoherent scattering, Equatorial regions, Earth(Planet), High resolution, Spatial distribution, Earth(Planet), Data bases, Artificial satellites, L band, High rate, Spaceborne, Coherence, Degradation, Intensity, Geomagnetism, Distortion, Apertures, Propagation, Processing, Targets, Surfaces, Amplitude, Radar

Distribution Statement : APPROVED FOR PUBLIC RELEASE