Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

38 elements allows the beam to be steered electronically as a phased array antenna. This technique has been widely used in larger military manned aircraft and prototype 5G cellular comms base stations, but the systems are large and power-hungry as each element needs its own phase-shifting hardware with RF filters, amplifiers and digital processing. Metamaterials allow the size and weight of an antenna to be reduced dramatically and still provide a suitable level of performance. For example, the first metamaterial phased array antenna system for aircraft can detect a light aircraft at 3 km, which is more than enough for detection and avoidance applications. Using metamaterials in a phased array opens up other advantages. Because complex voltage patterns can be applied to the metamaterial array, the antenna can track up to 10 objects in the air while still scanning the airspace for other objects. That is not possible with traditional radar systems that scan and then lock onto an object to track it. The ability to track multiple objects is increasingly in demand as multiple UAVs may be in the air at the same time, and they will all need to be tracked to avoid a collision. Another advantage of an electronically steered array is when a craft is near the ground, typically about 100-1500 ft and mostly at around 300 ft. A traditional radar creates a lot of clutter from reflections from objects on the ground, and this clutter needs to be filtered out. Using the phased array to generate a narrow beam with a ±40 º elevation to avoid ground clutter and adjust itself when the UAV changes direction, dives or climbs, again significantly reduces the load on the back-end processors. This would be particularly relevant for package delivery UAVs that need to avoid obstructions on the ground. The phased array radar can take advantage of established algorithms such as a binary search pattern that can identify areas of interest. The beams checking that area can be interleaved with five beams per second, and then search-scan algorithms can be used, giving confidence that the track won’t be lost. This data can also be fed back into the radar control system. For example, if there are objects that are potential threats then more beams can be allocated to track the objects while maintaining a general scan. The first version of this phased array radar measures 8 x 4 in (203 x 101 mm) and is 2 in thick; it consumes 35 W of power for a 1 W RF power beam output. Waste heat management makes up October/November 2018 | Unmanned Systems Technology Metamaterials have enabled a compact, low-cost phased array radar system that can be used in air and ground systems for collision detection (Courtesy of Echodyne) Fortem’s TrueView radar is designed for UAV operation (Courtesy of Fortem Technology)