Nothing lasts forever. This drone, powered by inductive coupling, can fly nearly indefinitely – but it isn’t quite a perpetual motion machine.

Developed by Imperial College London researchers and announced on Oct. 20, the wirelessly powered drone could recharge in the air. It uses inductive coupling, a method first demonstrated by Nikola Tesla in which copper coils can be used to wirelessly exchange power. The drone would only have to hover over a companion vehicle or another drone in order to create direct current (DC) voltage.

The researchers used a quadcopter purchased off-the-shelf, then rearranged its electronics to include a copper foil ring around the casing. This serves as a receiving antennae for a transmitter on the ground, which generates a magnetic field.

The transmitter, which is itself connected to a power source, generates a magnetic field. The drone’s electronics are adjusted to the same frequency as that magnetic field, meaning that the field produces an AC voltage in the drone which can be converted into DC voltage that powers its electronics.

“There are a number of scenarios where wirelessly transferring power could improve drone technology,” said Sam Aldhaher, a researcher with the college’s Department of Electrical and Electronic Engineering. “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.”

However, the wireless charging has a very short reach. At this stage in the research, the signal can only be transmitted ten centimeters. The researchers hope to have a commercially viable version available in a year, giving drones wider ranges and more potential applications for wearables, surveillance, and construction.