SAR autofocusing viewed as adaptive beamforming on prominent scatterers

The SAR phase correction information can be extracted from beamforming source echoes at different range gates. An ideal point source induces a field of constant amplitude across the array. Lower echo contrast can therefore be identified with higher quality sources. It is shown that by using contrast measurements on phase history domain SAR data, the contributions of phase synchronizing sources at different range gates can adequately be combined to produce an optimal SAR impulse response having the lowest possible ISLR