Abstract: The single-antenna radio frequency (RF), direction finding (DF) system includes a single-element directional antenna, which is mounted on a multi-rotor UAV (Unmanned Aerial Vehicle) and integrates with a DF algorithm for tracking an RF source in the 2.45 GHz ISM band (or any other frequency band). The algorithm will depend on the rotating nature of the platform to scan the azimuth, as well as several elevation angles with respect to the platform axis of rotation, and thus be able to accurately locate the coordinates of the RF transmitter based on the recorded power levels. The RF source determination step is performed during the search mode of the algorithm. The RF transmitter location is saved, and the UAV takes actions accordingly by commencing movement towards that location in the action mode of the algorithm. After some time, the UAV enters the search mode again in case the RF source has moved.