Focusing of synthetic aperture ultra wideband data

The synthetic aperture radar (SAR) focusing problem is considered, with special attention given to focusing an area in the near-field of the synthetic aperture over a decade or more of bandwidth in a manner that preserves target resonance characteristics. An approximation that reduces the computational load is shown. An error analysis of the approximation shows quantitatively what conditions are required to guarantee that the depth of focus is adequate to preserve long-duration target resonance effects.<>