Two-dimensional autofocus technique for stepped-frequency ISAR imaging

A new ISAR autofocus method based on the subarray averaging concept is developed to compensate for the phase errors along down-range dimension. The results in this paper show that the ISAR autofocus based on the subarray averaging concept makes it possible to reconstruct high quality ISAR images even though a target moves with very high speed, and a stepped-frequency signal with low PRF is used.