Chinese scientists have developed a special power transmission platform to charge drones mid-air using microwaves, a proof-of-concept design that may one day lead to UAVs flying indefinitely.
Researchers from China’s Xidian University envision the platform to be developed into a land-based vehicle capable of launching and extending the operational reach of drones.
Tests conducted by scientists showed that the car-mounted system could keep fixed-wing drones in the air for just over 3 hours at an altitude of 15m.
The car-mounted power transmission system used a microwave emitter to beam energy to an antenna array on the aircraft’s underside, doing so while both the drone and the charging system were in motion.
However, maintaining alignment between the microwave emitter and the drone was difficult, researchers noted in a study published in the journal Aeronautical Science & Technology.
This required close coordination between GPS positioning and onboard flight control systems, they said.
Scientists noted that the system was still in infancy as only about 3 to 5 per cent of the beamed energy reached the drone, with a vast majority of the microwave energy wasted.
Ultimately, the power received by the drone also fluctuated due to wind and positioning errors.
The team was led by Xidian University professor Song Liwei, a specialist in the research of antenna structures and microwave wireless energy transmission.
In recent years, the concept of converting ambient and directed electromagnetic energy into usable direct electrical power has transitioned from a research prototype stage to a standardisation-ready technology.
Last year, the US Defence Advanced Research Projects Agency (Darpa) achieved a new record in transmitting energy over distance, relaying 800 watts of power using a laser beam over 8.6km for over 30 seconds.
While the efficiency of the system was only about 20 per cent, Darpa noted that improvements were possible as the technology became more affordable.
An ongoing US defence project is aiming to develop a “wireless energy web” for near-instantaneous energy transport.
Unlike the latest Chinese study, the Darpa design hopes to achieve long-distance power transmission using a ground-sourced laser passing through multiple airborne nodes and back down to a ground receiver.
The US agency hopes the network will enable unlimited range or endurance for fleets of drones.
