The effect of SAR bandwidth ratio and current variation on ocean current measurements by along-track SAR interferometer

Describes the principle of the multi-antenna airborne synthetic aperture radar (SAR) interferometer operating in the along-track mode for ocean current measurements. Three new and important results are obtained. The first is that if the azimuth processor bandwidth is comparable with or wider than the signal bandwidth (illuminating beam width), the phase extracted from the mutual coherence function (MCF) or interferogram depends on this bandwidth ratio as well as the current velocity. The second result is that if the current velocity changes in azimuth direction, then the extracted phase does not faithfully represent the current variation. Third, it could be argued that interferometers in shorter radar wavelengths (such as X-band) may be superior than those in longer wavelengths; the choice also depends on the scene coherence time of the ocean.