Influence of Turbulences and Cross-Wind on the Signal Quality in Circular Synthetic Aperture Radar

Airborne Circular Synthetic Aperture Radar (CSAR) measurements provide very high resolution, independent of the signal bandwidth. However, non-ideal flight conditions, such as turbulences or cross-wind, severely affect the coverage of the target area on the ground. The SNR of the received signal is reduced, and features in the image are more likely to be covered by noise. This paper analyzes these effects based on a flight campaign using the airborne F-SAR sensor of the German Aerospace Center (DLR), operating in C-band. It compares the results with an ideal steered antenna pattern, which mitigates the influence of turbulences. The ideal focused antenna pattern shows an improvement of 7.8 dB. The required beam steering angles for focusing the antenna footprint are presented as well, which potentially can be used to design future active phased array antennas, capable of compensating turbulences.