In-situ characterization of international low-frequency aperture arrays by means of an UAV-based system

Low Frequency Aperture Array (LFAA) systems are opening up new frontiers for ground-based radio astronomical instruments. These instruments require advanced measurement procedures and systems for characterization and calibration of their front-end. For this purpose, a test source mounted on an Unmanned Aerial Vehicle (UAV) has been developed in Italy. This system has proven to be a reliable, accurate, portable and effective tool to characterize LFAA systems as demonstrated during measurement campaigns on two Aperture Array Verification Systems for the LFAA of the SKA in the UK and on a LOFAR station in The Netherlands. This contribution gives an overview of these campaigns, the continuous development of the UAV-based measurement system and the envisaged future improvements.