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In-flight wireless power transfer for drones

Scientists at Imperial College London have demonstrated a highly efficient inductive method for wirelessly transferring power to a drone while it is flying. Theoretically, this wireless power transfer (WPT) technology could allow flying drones to stay airborne indefinitely by simply hovering over a ground support vehicle to recharge. The team estimates it is one year away from a commercially available product.

The technology uses inductive coupling, similar to the technology being developed for WPT for electric vehicles. To demonstrate their approach, the Imperial College London researchers bought an off-the-shelf quadcopter drone—around 12 cm (4.7 inches) in diameter—and altered its electronics and removed its battery. They made a copper foil ring receiving antennae that encircles the drone’s casing. On the ground, a transmitter device made out of a circuit board was connected to electronics and a power source, creating a magnetic field.


The drone’s electronics are tuned or calibrated at the frequency of the magnetic field. When it flies into the magnetic field, an alternating current (AC) voltage is induced in the receiving antenna and the drone’s electronics convert it efficiently into a direct current (DC) voltage to power itself.

The technology is still in its experimental stage. The prototype WPT drone can currently fly only 10 cm (3.9 inches) above the magnetic field transmission source.

The use of small drones for commercial purposes, in surveillance, for reconnaissance missions, and search and rescue operations are rapidly growing. However, the distance that a drone can travel and the duration it can stay in the air is limited by the availability of power and re-charging requirements. Wireless power transfer technology may solve this, the team suggests.

There are a number of scenarios where wirelessly transferring power could improve drone technology. One option could see a ground support vehicle being used as a mobile charging station, where drones could hover over it and recharge, never having to leave the air.

—Dr Samer Aldhaher, a researcher from the Department of Electrical and Electronic Engineering at Imperial College London

Wirelessly transferring power could have also applications in other areas such as sensors, healthcare devices and further afield, on interplanetary missions, with the drone wirelessly transmitting power to other devices.

Imagine using a drone to wirelessly transmit power to sensors on things such as bridges to monitor their structural integrity. This would cut out humans having to reach these difficult to access places to re-charge them. Another application could include implantable miniature diagnostic medical devices, wirelessly powered from a source external to the body. This could enable new types of medical implants to be safely recharged, and reduce the battery size to make these implants less invasive.

In the future, we may also be able to use drones to re-charge science equipment on Mars, increasing the lifetime of these billion dollar missions. We have already made valuable progress with this technology and now we are looking to take it to the next level.

—Professor Paul Mitcheson, Department of Electrical and Electronic Engineering, ICL

The next stage will see team exploring collaborations with potential industrial partners.



If the drone has to be 3.9 inches from the charge coil, what is the advantage? Land, switch of and charge at a much faster rate.


The space elevator uses microwaves, just aim beam for power.


Better yet just use a direct methanol fuel cell.

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