A Theory of Multiaperture Along-Track Interferometric Synthetic Aperture Radar

In this letter, a novel theory is proposed to measure the velocity vector of moving targets such as ocean currents by multiaperture along-track interferometric synthetic aperture radar (MA-ATI SAR), utilizing the conventional dual-antenna ATI SAR data. In this system, the range component of the velocity vector is first computed with the conventional ATI SAR algorithm by correlating the two sets of complex images produced through the fore and aft antennas. For estimating the direction of the velocity vector, multilook/sublook processing is applied to two sets of range-compressed azimuth raw data. Now, there are four sets of complex subimages, two of which are forward-looking and the others are backward-looking. Then, from these subimage pairs, the two sublook interferograms of the corresponding directions are produced. The direction of the moving targets can be estimated either from the forward- and backward-looking azimuth velocity components, or directly from the interferometric phases. With this direction and the range velocity component, the velocity vectors of ocean currents and also moving hard targets on land and sea can be estimated.