SAR detection of wires using image phase signatures

Abstract

Analyses of high resolution UHF synthetic aperture radar images have uncovered a deterministic phase signature of a long wire. Given k/sub 0/ as the wave number and R as the range of a focused image pixel to the phase center of the SAR aperture, a factor exp(-j2k/sub 0/R) is imbedded in the complex target image signal return. This linear image phase variation results in a long, narrow wire spectrum in the spatial frequency domain orthogonal to the wire in orientation and is frequency shifted from the origin of the spectral coordinates. This spectral feature enables coherent processing such as spatial filtering and integration to improve significantly the signal-to-clutter ratio of a wire and its detectability in the clutter environment.