"The Power of Induction" by Davide Castelvecchi in the July 21,2007 posits that "cutting the last cord could resonate with our increasingly gadget depentdent lives." The on line article may be up next week as Science News usually delays selected articles a week before putting them online (see below.)
He describes an experiment where power is transmitted magnetically within the near field by making the E & M components out of phase instead of in-phase as in ordinary inverse square field, out of phase transmission. Up to 40% efficiency at room size distances, e.g. from the AC outlet to common lamps, phone chargers, etc. thus freeing us from mazes of power cords. His whole idea came from having a cell phone beep in the middle of the night from low charge.
Tesla and early power transmission work is referenced. Tesla's tower and the withdrawal of funding is mentioned, but not known to be transmitting power by the same method.
Basically the coils of transmittal and reception are very ineffecient, much below half wave size but are resonant with each other. In the experiment, 10Mhz, 30 meter wave lengths are used the major loss of efficiency being copper heating losses in the coils. A few meters from the source the power drastically drops off. "Eventually you have to face the fact that the fields decay very fast," says Soljacic.
Article: "If Soljacic's far out idea bears fruit and engineers manage to squeeze WiTricity into electronics products, then in a few years homes, workplaces, and coffee shops could be pulsating with agnetic energy, greatly reducing the tangle of cords.. and plug ins."
Asked why something so elementary was not 'discovered' before or utilized, the inventor, Soljacic says "though a simple principle, many things look simple from hindsight." Shanhui Fan, a physicist at Stanford says," the use of magnetic resonance as a means of transferring energy is a completely new concept."
I imagine (very hopefully) if this technology comes to fruition that the frequencies used will be higher and not in a hamband. Sojacic and colleagues have applied for two patents and is describing the system as WiTricity. -Another very powerful emmision competitor to claim frequencies.
I kid you not about the whole thing. So close to what we do and yet not quite the same beast.
I know, I know, but get an issue and read the article. Amazing what's missed until the demand is there, in this case a myrid of wires powering more and more stuff.
www.sciencenews.org
