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Re: About wireless energy transfer



Original poster: Ed Phillips <evp@xxxxxxxxxxx>

Tesla list wrote:

Original poster: "David Thomson" <dwt@xxxxxxxxxxxx>

Hi Jim,

> I couldn't resist flaming Soljacic for not mentioning Tesla in the news
> release/article. Let's hope he gives credit where credit is due.

In all fairness, Soljacic recognized Tesla's previous efforts in wireless
power transmission in his published paper.  The press stories are often
written by science writers, who determine for themselves what and what not
to print.

Dave

I've just read the paper again and am more convinced than before that while Soljacic and his coauthors found Tesla's name somewhere their paper DOESN'T recognize Tesla's efforts AT ALL; he doesn't deserve any "fairness". Their ONLY mention of Tesla [or anyone else except in the references] says:

"In the early days of electromagnetism, before the electric-wire grid was deployed, serious interest and effort was devoted (most notably by Nikola Tesla [1]) toward the development of schemes to transport energy over long distances without any carrier medium (e.g. wirelessly)."

Their reference [1] is to the "Wardenclyffe" patent of 1914 (original filing 1902) which, as I noted before, is for a transmitter only and which I think they never read. They are apparently totally ignorant of the very wide-spread deployment of the "electric wire grid" by 1900 or of the work of Tesla in connection with the Niagra Falls project at an even earlier time, again indicating that they're living in a different world of technology from the rest of us. They further state that their system would of use for, among other things, RFID systems. If they knew anything about RFID practice they would know that some of these devices have been using their EXACT scheme for almost 10 years.

Further on in the paper they disclose the principles of their marvellous discovery:

"The basis of this method is that two same-frequency resonant circuits tend to couple, while interacting weakly with other non-resonant elements." If they intended to give ANY recognition to Tesla and had done ANY serious research about "prior art" they would have added something like "as demonstrated on a large scale by Tesla in his Colorado Springs experiments in 1899". Obviously they had NO idea of Tesla's ideas or the extent of his efforts.

I just did a quick check to see what is in some of my earlier "wireless" reference books. Zenneck's "Wireless Telegraphy", originally published in 1906, has an extensive discussion. Pierce's "ELECTRIC OSCILLATIONS AND ELECTRIC WAVES" (1920) devotes six chapters to the subject of "The free oscillation of two coupled resistanceless circuits", discusses in considerable detail and in more familiar terms their "eigenmodes of the combined system" and gives many references to the subject dated before 1900. The first is Lord Rayleigh's "Theory of Sound" which I don't own. I'd be willing to bet he mentioned coupling between resonant acoustic devices. One reference which Soljacic and crew should have noted is readily available. It is "Amplitude Relationships in Coupled Circuits", E. Leon Chaffee, from a 1916 issue of the Proceedings of the Institute of Radio Engineers. Their figure of merit "k/sqrt(Gamma 1 Gamma 2)" appears in Pierce and probably in Chaffee in the form more familiar to radio engineers - "k sqrt (Q1 Q2)" which can be found in any radio textbook.

In summary, except perhaps for their discussion on dielectric resonators, there's nothing new here except the obscure terminology and beautiful pictures. Those cats didn't "recognize Tesla's efforts" - obviously they have no idea at all of what they were or how far they went over a century before their work.

Ed