UAV-Based Multistatic Synthetic Aperture Radar System and Applications

Abstract

At the German Aerospace Center (DLR) we are currently building up a distributed UAV-based synthetic aperture radar (SAR) system for remote sensing applications and preparation of future new space radar missions. The system is scalable and consists in its basic configuration of three multicopters, each carrying a fully digital and polarimetric multi-channel radar sensor covering a frequency span from 500 MHz to 3.5 GHz with an instantaneous bandwidth of 3 GHz. Due to the relatively low carrier frequency even subsurface imaging is possible. The flight time is around 40 min so that per flight an area on ground of at least 1 km² can be imaged. For multistatic imaging the radar sensors need to be operated coherently among each other. This requires special radar synchronization methods and additional onboard hardware. Furthermore, the geographical positions of the radar antenna phase centers need to be known with subcentimeter accuracy, as well as the relative distance between the individual multicopters. Addtional to a standard RTK GNSS base station on ground, per multicopter a special developed RTK module with a high accurate inertial measurement unit and a modified data fusion algorithm is needed for reaching the required accuracies. In the talk the system concept, the radar hardware, the technical challenges and solutions will be discussed in detail. Furthermore, some of the envisaged applications like single-pass interferometry, tomography and holography will be addressed. This work was partially funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) GRK 2680 - Project-ID 437847244.