IMPROVED OMEGA-K ALGORITHM FOR HIGHLY SQUINTED TOPSAR WITH CURVED TRAJECTORY

In terrain observation by progressive scans synthetic aperture radar (TOPSAR) imaging with maneuvering platforms, acceleration distorts Doppler spectrum so that conventional unfolding methods are no longer applicable. Besides, the approximation of conventional frequency-domain algorithms exceeds the margin of error due to beam steering in TOPSAR mode. To solve these problems, an improved omega-K algorithm with 2-D spectrum recovery is proposed, in which compensation functions and phase filters are first constructed to eliminate distortion and folding of the wavenumber spectrum so that the utilization of 2-D wavenumber spectrum support region becomes maximized. Aiming at accompanying spatially variant Doppler parameters, the resampling method is performed to equalize the FM rates of targets in the same range cell. Finally, point target simulation shows that the proposed method can handle more complicated TOPSAR geometry than the previous algorithms.