The researchers also built a separate transmitting platform that uses a circuit board, power source and copper coil of its own to produce a magnetic field. When placed near that platform, the drone's coil acts as a receiving antenna for that magnetic field, inducing an alternating electrical current. The quadcopter's rejigged electronics then convert that alternating current to direct current, which is used to power its flight.

Known as inductive coupling, the technique has been around since the time of Nicola Tesla. According to Imperial College, however, this is the first time that it has been used to power a flying vehicle. While it currently only works if the drone is within 10 cm (3.9 in) of the transmitter, it is hoped that the range can be greatly increased.

The first use of radiant power, or the wireless transmission of power, was arranged by the matchless inventor Nikola Tesla. The largest Tesla Coil ever built (the 'Magnifying Transmitter') could generate up to 300,000 watts of power, and produce a bolt of lightning 130 feet long. Tesla actually managed to successfully transmit about 30 to 50 thousand watts of power without wires using the coil.

However, it was left to Robert Heinlein writing in his classic 1942 novella Waldo to really set imagination free and imagine what you could do if you didn't need to carry some sort of stored power in your flying vehicle.

"...We'll use my 'broomstick'".

Grimes let his eyes run over his friend's fusiformed little speedster. Its body was as nearly invisible as the plastic industry could achieve. A surface layer, two molecules thick, gave it a refractive index sensibly identical with that of air. When perfectly clean it was very difficult to see.

At the moment it had picked up enough casual dust and water vapour to be faintly seen - a ghost of a soap bubble of a ship.

Running down the middle, clearly visible through the walls, was the only metal part of the ship - the shaft, or, more properly, the axis core, and the spreading sheaf of deKalb receptors at its terminus. The appearance was enough like a giant witch's broom to justify the nickname. Since the saddles, of transparent plastic, were mounted tandem oven the shaft so that the metal rod passed between the legs of the pilot and passengers, the nickname was doubly apt.
(Read more about Heinlein's broomstick speeder)