Autofocus for SAR images in strongly asymmetrical bistatic configurations

ONERA experimented bistatic satellite to aircraft SAR imaging with its lightweight SAR system BuSARd receiving TerraSAR transmitted signal at X-band with two channels for direct and terrain scattered paths. Static receiver experiment shown that the direct path signal is instrumental in clock synchronisation. Later, two flight experiments with anti-parallel and parallel paths were conducted showing that the trajectory error influences the focusing mainly through the clock synchronisation error from non-modeled direct path length. Significance of the receiving aircraft velocity was also emphasized from the anti-parallel acquisition.