AN OBSERVATION ABOUT RADAR IMAGING OF REENTRANT STRUCTURES WITH IMPLICATIONS FOR AUTOMATIC TARGET RECOGNITION

The standard inverse synthetic aperture radar (ISAR) high-frequency we ak-scatterer model is inappropriate to targets with inlets and cavitie s, and images created under this model assumption often display artifa cts associated with these structures. Since inlets and cavities (typic ally) make a strong contribution to the radar field scattered from air craft targets, these artifacts often confound the image interpretation process and considerable effort has been spent in recent years to mod el, isolate, and remove these sources of error. Many of the more compl ete and accurate scattering models require extensive knowledge about t he cavity/inlet shape and size and, moreover, are numerically intensiv e-features that make them unsuitable for many imaging applications. We examine an older (and less accurate) model based on a weak-scattering modal expansion of the structure which appears to be well suited to I SAR imaging. In addition, the analysis shows how cavity/inlet shape-sp ecific information may be estimated from an ordinary ISAR image.