Synthetic Aperture Radar Correlation Imaging

In synthetic aperture radar (SAR) imaging, a scene of interest is illuminated by electromagnetic waves. The goal is to reconstruct an image of the scene from the measurement of the scattered waves using airborne antenna(s). A new imaging algorithm, known as correlation imaging, is suggested in which an image is formed of the reflectivity function squared. The algorithm uses what is often called the correlation function in place of the standard slow-and fast-time data. The correlation function is found via a simple preprocessing step applied to the collected data. A backprojection algorithm is formulated using microlocal analysis. It is found that range and cross-range resolution are improved compared to standard SAR imaging. In addition, the point-spread function (PSF) of the correlation image-fidelity operator exhibits reduced side lobes in comparison with the standard SAR PSF. We also show that the contribution to the image from clutter displaying volume scattering behavior is reduced when certain pairs of correlated data sets are avoided. Note that by clutter we refer to scatterers on the ground that are not of interest; we do not address the case of propagating through a random (i.e., cluttered) medium.