Monopulse Radar for Obstacle Detection and Autonomous Flight for Sea Rescue UAVs

This paper presents a Monopulse radar at 24 GHz which was designed to detect obstacles during autonomous flights of an unmanned aircraft system executing sea rescue operations. The radar consists of one transmit and four receive antennas, which are placed in a square formation close to the transmit antenna. By evaluating the time-ofarrival parameter from the pair of two vertically displaced antennas the calculation of the elevation angle becomes possible in addition to the azimuth angle, which is determined by the pair of two horizontally separated antennas. Thus, the received radar signals can be used for detection and tracking of targets in 3D space. A specific constant false alarm rate (CFAR) was implemented which applies an appropriate threshold that maximizes the probability of detections and keeps the probability of false alarm below a preset level. First test flights were carried out to validate this radar and target detection.