American researchers say they are now able to transmit power wirelessly across short distances. The technology may prove a boon for gadget enthusiasts with more devices than power sources.

The technology stems from the concept of resonance, a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. As with musical instruments, the technology builds on the fact that oscillation spreads between objects sharing the same resonance frequency.

The principle works in the same way for electromagnetic waves as it does for sound waves. A research team at MIT has begun trials to direct oscillatory waves between two objects, thus allowing power to transfer from one to the other.

Channel resonance rather than waste it

Existing systems that use electromagnetic radiation, such as radio antennas, are not suitable for the efficient transfer of energy because they scatter energy in all directions, wasting large amounts of it into free space.

Tests are thus being made on so-called 'non-radiative' objects that keep resonances close when energy is applied, rather than letting it escape into space. That way, a device that is put close to the resonance source and using the same frequency could be charged up without significant loss of energy. The US researchers say that standard copper antennas could easily be adapted to do this.

The system has yet to be trialled in practice, but according to researchers the computer models and the mathematics behind it prove that the system could transmit power across distances up to five metres.

The aim is to develop wireless power supply, primarily for home electronics, but the technology could also be adapted for larger-scale industrial use.