A new formula for SAR spatial resolution

The fundamental limits of SAR spatial resolution is investigated in this paper. Conventional SAR resolution formulas are not applicable to ultra-wideband and wide-beam systems since they do not consider the dependence of system frequency response in the along- and across-track directions, We derive an expression for the SAR transfer function, from which the impulse response function may be determined. A general resolution formula is also obtained directly from fundamental time-frequency relations which agrees with conventional formulas in the narrow-band and narrow-beam limit. The new resolution formula is accurate provided the system has a large ratio of integrated mainlobe-to-sidelobe energy and the distance to the imaged area is much larger than the longest transmitted wavelength.