Electromagnetic image of small UAV in very low frequency range

The article deals with the measurement, visualization and analysis of the magnetic field in the 3D space around a small quadcopter. The measurements were realized in the very low frequency (VLF) range, since this range is interesting because of the possible detection of the drone also in the fully automated flight mode (without telemetry transmission). A measurement equipment/device that allows mapping of the magnetic field of the multirotor drone based on the sensor elevation and the copters azimuth was realized. The magnetic field was measured with a small inductive sensor – the air coil. Frequency analysis (signal spectrum) and the spatial 3D analysis of the selected frequency components that brought interesting results were carried out on the recorded data.