Sidelobe apodization for high resolution of scattering centres in ISAR images

Inverse synthetic aperture radar (ISAR) image processing is useful in identifying and isolating dominant scattering centres of a target for subsequent placement of radar absorbing material (RAM). ISAR image construction artifacts have the potential of obscuring low intensity scatterers in the image as well as blurring regions where closely separated scatterers occur. Spatially variant sidelobe apodization (SVA) is a technique that reduces sidelobe levels in a Fourier image while maintaining the image resolution that would be obtained using the rectangular window. We investigate the application of 2 versions of SVA to the ISAR image of a ship; these are the standard cosine-on-pedestal SVA and the new Kaiser window version of SVA. It is found that either SVA approach is able to find and isolate scattering centres. We also found that when polar reformatting is required, neither SVA version is a substitute for it, but applying SVA after polar reformatting gives excellent results.