Acquisition, processing & autofocus issues of high resolution long range airborne synthetic aperture radar

Long range high resolution imaging from airborne SAR is a challenging task because the higher propagation losses are mitigated by higher transmitted power but also high gain (more directive) antenna. But as carrier aircraft is submitted to position and attitude random fluctuations due to air turbulence and pilot corrective manoeuvres, directive antenna requires two-axis steering for achieving illumination long enough for the required cross-range resolution (with highly directive antenna, spotlight or sliding spotlight imaging mode are mandatory).