Passive bistatic SAR imaging — Challenges and limitations

One widely used imaging technique in Earth observation nowadays is the synthetic aperture radar (SAR) method. It was proposed for the first time in 1951 by Carl Willey from the Goodyear Aircraft Corporation [1], [2], [3]. Wiley found that the Doppler history of the signals received by a radar mounted on a moving platform can be exploited to obtain a high resolution in the cross-range dimension (along the path of sensor movement). Another explanation of this technique is that the results of an observation taken from subsequent points on a sensor's trajectory may be interpreted as if they came from different antennas in a huge array. Combining this concept with pulse compression in the range domain, it is possible to obtain a high-quality, two-dimensional image of the Earth's surface.