The AM Forum

Echos of Tesla, or new source of HF QRM?

US researchers have successfully tested an experimental system to deliver power to devices without the need for wires.

The setup, reported in the journal Science, made a 60W light bulb glow from a distance of 2m (7ft).

The system exploits "resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied.

In the experiment both coils were made to resonate at 10Mhz, allowing them to couple and for "tails" of energy to flow between them.

Using low frequency electromagnetic waves, which are about 30m (100ft) long, also has a safety advantage according to Professor Pendry.

http://news.bbc.co.uk/1/hi/technology/6725955.stm

Here's how it works, A SSB signal is generated on a frequency of 3885 and is mixed with an existing carrier in the same passband. This causes the carrier to increase power to compensate for a decrease in signal to noise ratio. Presto, wireless power transfer! But really, the news story makes it look like MIT invented it  ::) Fact check...not.

You're right Don, that is indeed Tesla's idea, and perhaps the only practical way to get around the power loss squared v distance law.

As I understand it, what he was aiming for was something like Schumann resonance.
http://en.wikipedia.org/wiki/Schumann_resonance

If only this had come to pass, we might not be fighting wars in the Middle East.

(http://www.teslascience.org/archive/photographs/WP001.jpg)