The characterization of electromagnetic fields radiated/received by installed antenna systems is a very important challenge for all the modern communication applications including audio/video broadcast, cellular, naval and aerospace as well as science cases such as the development of the Square Kilometer Array (SKA). In this framework, a novel solution has been conceived. It consists of a properly-designed micro Unmanned Aerial Vehicle which is equipped with a radio-frequency transmitter. Such a setup operates as a flying test source for the characterization of installed antennas in their operative conditions. The reciprocal configuration i.e. a receiver on the drone has been also investigated.