Through the use of power-beaming, a type of far-field wireless power transfer, DARPA is developing a revolutionary technology that will allow drones to be wirelessly charged in mid-air. By removing the need for drones to return to base for battery replacements or recharging, this invention has the potential to completely transform drone operations and save vital time and resources during vital missions.
At the vanguard of this technology is Dr. Ifana Mahbub, an assistant professor of electrical and computer engineering at The University of Texas. In 2021, she was given a DARPA Young Faculty Award, which will give her $500,000 for two years of research funding. DARPA just awarded an extra $250,000 to advance this exciting invention.
Far-field technology aims to deliver electricity over considerably greater distances than near-field wireless charging, which is already widespread in devices like smartphones and uses low-frequency electromagnetic waves over short distances. The basic idea is that an electromagnetic field is created by a coil-equipped charging unit, which is then picked up by a receiving coil within the drone, producing electrical current to charge the battery.
Mahbub’s team is tackling the challenge of preventing electromagnetic beams from scattering and losing power over large distances. They are employing phased-array antennas—a system of transmitters and smaller antennas that direct the electromagnetic beam along a specific path. This approach leverages the real-time telemetry of UAVs to maintain a line-of-sight connection for optimal charging efficiency. “The signal can go in undesired directions,” Mahbub notes. “Our goal is to engineer the waveform to minimize path loss.”
This technology holds promise for various drone types, including Medium Altitude, Long Endurance (MALE) UAVs flying up to 25,000 feet, High Altitude, Long Endurance (HALE) drones operating at 50,000 feet, and tactical drones flying between 2,000 and 5,000 feet. Beyond drones, potential applications include charging electric cars on freeways and medical implants in people using safe, low-frequency electromagnetic waves.
Although the concept of powerful electromagnetic waves charging airborne devices might seem daunting, similar technologies have been safely used in radio, television broadcasting, cell phone service, radar, Wi-Fi, and GPS for years. However, it would be wise to avoid standing between the transmitter and the drone during charging sessions.