SAR DATA FOCUSING USING SEISMIC MIGRATION TECHNIQUES

Conventional algorithms for synthetic aperture radar (SAR) data focusing use the matched filter concept and convolve the data with a reference phase signal which changes with range. The resulting algorithm is space variant and its frequency domain implementation is cumbersome. SAR data, however, can be focused using migration techniques, quite similar to those used in geophysics. The frequency-wavenumber approach is extremely efficient: it attains almost the ultimate results in performance, with the efficiency of frequency domain implementation. The method is exact when the sensor flies along a rectilinear path, but even with a spherical Earth and a circular sensor trajectory the results are extremely good. Terrestrial swaths as wide as 100 km can be focused simultaneously with no serious degradation, at least with the spatial resolution at present used or envisaged in SAR missions. The algorithm has been tested with synthetic data, with SEASAT-A data and with airplane data (NASA-AIR). The experimental results fully support the theoretical analysis.