ABSTRACT
Synthetic aperture radar (SAR) can provide two-dimensional high-resolution radar images in azimuth and elevation dimensions. However, since two-dimensional radar images are obtained by projecting the three-dimensional distributed targets onto the twodimensional plane, they usually suffer from geometric distortions, such as foreshortening, layover, and so forth. Conventional SAR achieves range resolution based on the pulse compression technique and azimuth resolution based on the synthetic aperture principle, therefore two-dimensional high-resolution SAR image of large scene can be obtained. On the zero-Doppler plane, conventional SAR only has the resolving ability in the range direction, and is lack of the resolving ability in the angle direction. The main advantage of downward-looking SAR is the full ground range coverage without shadowing effects. Image formation processing is a key issue for downward-looking SAR three-dimensional imaging. A three-dimensional range migration algorithm (RMA) was proposed in and a three-dimensional RMA was proposed in for two-dimensional planar scanning aperture near-field imaging.
