Talk:Evanescent wave coupling

Inductive coupling?
Note that Evanescent waves are standing waves in the nearfield region surrounding matter, and are identical to the expanding/contracting EM fields surrounding any radio antenna, inductor, or capacitor, excited with AC. Evanescent wave coupling is only significant within about one wavelength from the medium involved, and also explains how EM energy is able to pass between the separate coils of a transformer, or the separate plates of a capacitor. In the case of total internal reflection, the evanescent fields are simply the electric and magnetic fields associated with the changing charges and currents in the partial reflector.


 * -This is simply inductive coupling. Why does it need its own article? WolfKeeper 22:27, 11 June 2007 (UTC)


 * -Why would they claim that it's 1 million times as efficient than inductive coupling then? — Omegatron 01:47, 12 June 2007 (UTC)


 * -I don't think they did. They said it's more efficient than non resonant inductive coupling.WolfKeeper 03:36, 12 June 2007 (UTC)


 * -The concept of evanescent wave coupling encompasses both inductive and capacitive coupling in the context of propagating waves. You're right, they should all be discussed in one article. Permittivity, susceptibility, index of refraction, capacitance, and inductance should also all be discussed in one article. Are you going to write these articles?128.220.251.100 15:25, 26 June 2007 (UTC)


 * -I am new to this Wikipedia editing. Sofar what I have added was always removed by someone. What I don't understand is why inductive coupling is limited to near-field distances. Who made up that rule. Believe me, if done right it goes a lot farther than that, and it can either be in the form of magnetic induction like a transformer (air core transformer in that case of course), or capacitive coupling so to speak using energy transfer by an electrostatic field. The mistake is calling it an evanescent wave coupling. It is not a wave since only one or the other field is used, not both at the same time. It is simply energy transfer by a magnetic field, or energy transfer by an electrostatic (or electric) field. My brother and I have two antennas registered with the Canadian Intellectual Property Office; you guessed it, one is a magnetic field antenna (reistration number: 2441882)and the other is an electrostatic field antenna ( registration number: 2469325). A patent has been granted for the magnetic field antenna as an underwater communication antenna, since magnetic fields penetrate water while radio waves do not. Using 3 watt CB radios, we have been able to communicate over a quarter mile with the antennas held about 10 feet under water. That is a lot farther than near-field The electrostatic field antenna is registered as a faster than light speed antenna as our tests indicate that it is useful over far-field distances. We have achieved distances of about a mile, but it does not work under water. The patent is still pending on that one. Our experiments which show that the signal transer is faster than light speed are described on http://www.wbabin.net/erdmann/erdmann.htm

if you care to take a look. Steinhauer 01:58, 22 September 2007 (UTC)

WiTricity
This is now being called WiTricity. Please create a redirect from that article title, or no one will ever find this material...-69.87.204.228 12:22, 9 June 2007 (UTC)
 * WiTricity has it's own page. Are they the same thing? Maybe they should be merged. Ewlyahoocom 18:01, 11 June 2007 (UTC)
 * Physically they are the same thing. However, the term WiTricity appears to be an application specific buzzword. In other words, the difference between WiTricity and evanescent wave coupling is analogous to the difference between WiFi and electromagnetic radiation. 128.220.251.100 15:38, 26 June 2007 (UTC)
 * Witricity appears to be a trade marked specific application of the general effect in the radio frequency band. Evanescent wave coupling appears at ANY wavelength, and as such there should be no redirect. This page is about the general effect. Please refrain from commercialising this page.Crusty007 (talk) 23:28, 4 March 2009 (UTC)

Evanascent waves are terms of a field distribution expanded in an exponential vector space that attenuate as they propagate. That is, they have complex propagation constants with negative real parts in their exponential functions. They represent stored energy and not propagating power. When one expands a field distribution in its exponential basis the terms which attenuate with distances are called "evanescent". Its that simple. No more, no less. So there is no greater mystery here than the very existance of electromagnetic fields to begin with. Remember fields are just mathematical creations to explain cause and effect observables so to infer so much from this evanescent field coupling is just nonsense. —Preceding unsigned comment added by 76.233.133.175 (talk) 20:09, 7 January 2011 (UTC)

Merging waves and articles
I vote for the suggestion that this page be merged with Evanescent Waves. As a non-expert of quantum physics, I have been dragged through these pages from the original article I selected, Quantum Tunnelling. Now I am following increasingly tedious links - it would be easier and more sensible surely to couple Evanscent Waves with their coupling? - JD (Biochemist not physicist!... trying to read about how protons tunnel in neurones... presumably with a quantum shovel?). —Preceding unsigned comment added by 60.240.156.100 (talk) 11:13, 16 July 2009 (UTC)


 * I copied the above comment by User 60.240.156.100 to the discussion at the "merger proposal" section of the Evanescent wave talk page. Steve Quinn (formerly Ti-30X) (talk) 02:44, 6 May 2010 (UTC)

Evanescent vs transient
"Transient" is a word most people understand, and "evanescent" is much less common and vaguer. Whether there's a difference between the two ought to be explained, and why "evanescent" is preferable. A "transient hotel" is one for "transients", that is, transient visitors, guests who are "in transit", that is, passing through. It's opposed to "resident hotel". Transient has a connotation of something which isn't expected to last long. To me, "protean" suggests changeable, variable, or mutable, but (unlike transient or evanescent) not likely to vanish. A transient (or transient voltage) is usually a spike. "Evanescent" to me suggests ghostly, ephemeral, or wispy, and possibly hallucinatory, suspicious, soon forgotten, other-worldly, paranormal. Something which is transient is expected to go away soon. Is that not applicable? What are we to think? Which connotations are accurate? Unfree (talk) 04:47, 7 March 2010 (UTC)

Evanescent waves may be long lasting with respect to time. This is the case for total internal reflection of a classical electromagnetic plane wave, where the evanescent wave would be permanent. The decay of the evanescent wave is with respect to space. Transient would be more appropriate for decay over time rather than decay over space. 130.64.34.134 (talk) 18:55, 19 February 2013 (UTC)