4HV WIRELESS TRANSMISSION THREADS

Tesla's Wireless System Thread Excerpts [Feb. 2009]: 

"Tesla's wireless system doesn't work, and that's why there's not more discussion of it." — Steve McConner, 4HV Moderator

"The creation of mathematical models that accurately represent the Tesla wireless system in operation is an important step towards its eventual implementation. Once again I find myself occupied with other matters and unable to more fully respond at this time. In the mean time I suggest reviewing the papers "Electromagnetic Field Theory" by Bo Thidé [and "A Generalization of Classical Electrodynamics for the Prediction of Scalar Field Effects" by Koen J. van Vlaenderenin] in preparation for future discussions." — Gary Peterson, 4HV Member

"We're all stocked up on pseudoscience for a while.  Both sides have had a chance to present their sides, but ultimately this discussion is not appropriate to 4hv.org.  There are many other sites out there that deal with Tesla's more fantastic claims that would be better suited to such a discussion." — Chris Russell, 4HV Administrator

Tesla Groups on the World-wide Web

• Tesla Universe (A discussion of Tesla's engineering legacy the modern age)

• Wireless Energy Transmission (forum for discussion of ongoing Tesla wireless system research)

• HV Community (forum for discussion of all high-voltage related topics)

• Tesla Experimental (forum for discussion of Tesla devices and amateur research)

• groups: usa-tesla (old International Tesla Society list)

• groups: Tesla-fy (somewhat indescribable)

• Tesla Coil Mailing List (e-mail listserv for Tesla coil hobbyists)

• groups: Tesla Turbine 

• groups: TeslaTurbineList 

• groups: Tesla's Flying Machine 

• groups: "Tesla" 

• Other yahoo Tesla groups 

• Other google Tesla groups 

Tesla Magnifier [June 10, 2007] - I think Tesla changed to 'magnifier' topology because he wanted maximum voltage at the topload WITHOUT breakout/arcs/sparks.  So the main reason for a magnifier topology seems to be for the wireless transmission of power—Sulaiman

 secondary resonance vs working frequency of the secondary coil - Tesla didn't want corona / sparks / arcs, high-voltage high-capacitance was more his thing (wireless transmission of power etc.)—Sulaiman

Is this wireless energy transfer? - . . . Just connect the receiver and transmitter to independent earth connections.  Due to the high impedances that the 'receiver' operates at a small earth rod/pipe would be more than adequate, or a few square feet of aluminium cooking foil laid on the ground.—Sulaiman

 Wireless power transfer - The transmission of wireless power is such an old topic that I'm sure Google will give answers, what I'm more concerned with is perception.  If people think that 50/60 Hz powerlines and/or cellphones are a health risk what will they (?) make of your pulsed-RF power transmitter?  What will the FCC position be? Especially since your transmissions are deliberate.  In this case I think that you should research the legal side before the technical.—Sulaiman

 Experiment movie - I made a few days ago an energy transmission experiment for one of my friends, with the miniDRSSTC. . . .—Member, ID #229

 Something to Do with All Those Extra HOTs - Since this circuit uses so few parts, it would be good for putting in a small box and made portable for wireless lighting demonstrations etc.—Member, ID #1225

wireless 'power' transfer? - In all fairness to Mr. Nikola Tesla, he was trying to transmit enormous amounts of power wirelessly over thousands of miles, not a few feet in a laboratory.  Its a huge stretch of the imagination to be able to say that TCs and magnifiers can transmit "usable" power wirelessly over distances by your experiment alone.—Moderator, ID #15

Experiments with piezos - I rather ran nicely standard brush and brushless DC motor (if you reread the end of [the previous] thread)—Marko Bakula

 tesla sypathetic vibration - In some cases when there is a high powerred tesla running and another secondary is set on the floor next to it, sparks will come off the sypathetic secondary that may only be grounded. . . .—Member, ID #195

Wee! My wireless power lives again! . . . —Marko

I'm also experimenting with wireless power transmission, and it's interesting what you said about the transmitting coil should have a high voltage/low current, because I have had the best results with a very low coupling on the transmitter (flat primary spaced below the secondary). Winding the primary onto, or over the secondary coil simply induces large currents in the windings of the secondary - not what you want in a transmitter!  I will post my results in the projects section in the next few weeks.  Basically the transmitter is a simple self-resonant SSTC, and the receivers are like an SSTC in reverse, with a bridge of ultrafast diodes on the *secondary* (careful!)—Member, ID #103

 Tesla coils do have a use! - The company I am currently doing some consultancy work for (EMC) has shown an interest in using a Tesla-type wireless power transmission system in their future products. . . .—Member, ID #103

For 'walled' applications it's definitely not good, but could be used in 'single room' applications with adequate grounding (grounding is usual problem here).  Anyway it would be really interesting to see some of such 'industrial' TC's and resonators and how these scale it down.—Marko

You may want to contact D.C. Cox as he has been building Tesla Coils professional for many years for a lots of customers and museums and may have good input.—Member, ID #290

Wireless powering SSTC - I had these larger 400kHz resonators sitting around unused. I thought it'd be cool if I could demonstratively power something wirelessly via capacitive coupling - and I decided to make that this coil's main use. . . . I built some kind of stand for receiver resonator, still have to do capacitive ground points... that's going to be something simple, probably AL foil on PVC sheet, or something like that.—Marko

 Post Your Cool Pic Here! - Wireless bulbs omg —Marko

 A failed SSTC project - I was full of expectation about your wireless project . . . —Member, ID #1025

I have started building a new inverter, and would really want to finish it this summer.  Going to do the initial work with IRFP450's and only switch to bigger mosfets after the first fail after being pushed *to the end.* —Marko

 Formerless coils for lightweight applications

"resonance" hype on BBC news - The thing I find absurd about this article is not that it may be BS, but the technology is older than I am...someone has just discovered that it can be made "fashionable" by charging your cute little electronic "lifestyle" devices with it.—Moderator, ID #29

 Witricity - I think the reason it's all over the place is that it's being misrepresented, or at least misunderstood.  Every article I've seen on this subject has been full of misinformation, and bad science.  The whole thing seems to be just a rehash of Tesla's attempts at wireless energy transfer, but with new buzz words.  Every time I see the phrase "non-radiative wireless power," I am painfully reminded of "non-Hertzian waves."  The references to Tesla, neglecting to mention the fact that he failed to make it work after years of trying, really seal the deal.  You might be able to power your laptop with a few feet using this technology, but you're not about to be able to walk all around your house and not worry about power.—Chris Russell, Administrator

 ''nonradiative radiation'' - Sure, I've got nonradiative radiation right here. I keep it in a virtual cupboard with the non-stick glue and the water-resistant water.  What we have here (IMO) is radiation of the ordinary, radiative sort, but trapped inside a waveguide. The arrangement of ferrite blocks and coils used doesn't look anything like a coax cable or microwave plumbing, but it is a waveguide nonetheless.  The fields generated by the apparatus have a non-reactive part, they must do in order to transfer energy. But the non-reactive part probably has an impedance greatly different to the impedance of free space, so it can't propagate well in free space. It can only exist inside the "waveguide" whose impedance is a better match to it. So, I'd rather refer to it as guided radiation than "non-radiative."  That's what I think, anyway. I find all this stuff very confusing too!—Steve McConner

Wireless energy again - That circuit in the BBC link doesn't make any attempt to direct or radiate the energy.  It just creates a big throbbing reactive field that fills most of the room, from which another tuned coil can extract energy.  Because it's not radiating anything, it doesn't need to direct.  But the flipside of that is that the range is extremely short.

It's basically the same as Tesla's schemes, except they left the Tesla resonators out and just used the primary coils.  Without the step-up effect of the resonator, the field is much lower impedance: it's all H with very little E, whereas a Tesla coil gives you all E and hardly any H. So, we can expect that most of the energy losses in the new system will be from eddy current heating of objects in the room, whereas with the classical Tesla system, it would be dielectric losses . . .  

Regardless, both of these E/H ratios are poor matches to the impedance of free space, so you can be sure that the fields are strongly reactive and not much power will get radiated.  This is always the case when an antenna occupies a region that is small compared to a wavelength. .—Steve McConner

Steve is correct about his point.  The entire thing is actually about transmitting the power without radiating it.  Power can be transferred in near field via capacitive or inductive coupling, and it is magnetic in this case.  And I bet Tesla played with both of these 100 years ago.  A Tesla resonator excited at resonance will develop enormous voltage on its top-load.  Another resonator brought in vicinity will show a tiny inter-capacitance with transmitting resonator.  The 'receiver' is tuned to resonance to present as high as possible impedance to the transmitter, for lowest losses.  High impedance can be converted to low by putting the load on resonator's base or using a magnetically coupled winding.  With each cycle, small amount of energy is transferred through small coupling capacitance and most of it remains stored in top-load capacitance, and some (unfortunately too much for us) is dissipated as ohmic loss in resonators.  Magnetic coupling is pretty analogous.  But this time it is parallel so current experiences resonant rise instead the voltage, and there is small mutual inductance between 'transmitter' and 'receiver'.  Again, small amount of energy is transferred with each cycle while most is reactive.  The receiver is tuned resonant to represent lowest possible impedance to transmitter, and converts it back into high(ish) impedance on its far ends to power the light bulb.  They seemingly still needed additional windings for impedance matching, though.  Note that there is no absolutely any kind of radiation anywhere in both cases, and actually any EM radiation escaping the system is considered a loss.  I don't know how to model radiation characteristics for a helical resonator; my antenna theory knowledge sucks in overall.—Marko

+1 on what Firkragg said.  He just more or less described Tesla's original plan for wireless power, and I believe this thing works the same way.

I don't know how to model the radiation characteristics either.  But I think, given that the antenna structure doesn't have any dimension larger than 60cm, and the wavelength of 10MHz is 30m, it's a fairly safe bet that it will suck completely as a radiator.  That is only 1/50 of a wavelength so the radiation efficiency would be a few %.  The measured Q factor of 950 also suggests that it is a lousy radiator.

I know this is just a new spin by some university PR department on Tesla's original ideas.  But maybe the time really is right for "Witricity" now...  Anyway, it looks like something that many board members here could lash up in an afternoon and I encourage you all to try it.  Replicating the experiment could get 4hv some good publicity if nothing else.

Yes, the difference is that Tesla didn't believe in the need for displacement current to close the circuit, he thought that only the ground connection was required.  We now understand EM theory much better and know that he was wrong: the displacement currents exist and act to cancel the ground currents in the far field, which severely limits the range of a Tesla wireless power system.

Note that displacement current and EM radiation are not the same thing.  You can transmit power by displacement currents in the near field while radiating hardly any of it to the far field, and conversely, a good antenna can radiate strongly to the far field without giving people RF burns and striking corona off things in the near field.—Steve McConner

Hi Steve, all,

. . . don't confuse displacement currents with EM radiation! . . . 
. . . The thing is actually very simple. . . .

Yes, the difference is that Tesla didn't believe in the need for displacement current to close the circuit, he thought that only the ground connection was required. We now understand EM theory much better and know that he was wrong: the displacement currents exist and act to cancel the ground currents in the far field, which severely limits the range of a Tesla wireless power system.

. . . all the time I thought that use of displacement current was his initial idea. . . .
 
As much as Tesla coils may be fooling to someone I really think Tesla was brilliant enough to realize that all electric circuits still need to always be closed. . . .

I would say that what truly limits the range of such system is solely efficiency of resonators.  All the loss occurs as ohmic loss on resonators themselves.  The small amount of radiation produced is also considered as a loss.  And Tesla coils as we have them are really poor on that part!

With ideal resonators of infinite Q you could transfer any amount of power through any distance (as long as you have ''ground connection'' though).

With real, but still super-realistically efficient resonators you could indeed transmit power over great distances with little loss.

As such the transmitter would give enormous voltages on its top-load for a little power input, and as receiver would also represent extremely high impedance voltage drop across capacitive resistance between them would be almost negligible.

In reality something as such is nearly impossible to achieve considering all the problems one would run into.  I've done some math on this.

One can increase the efficiency of a helical resonator by increasing its L/C ratio and decreasing ohmic resistance.  Once resistance is low enough it implies that we will have really massive base current flowing trough earth.  Effect would persist even if we make the resonator super conducting, making the earth itself biggest dissipater.

Breakout from the top-load would be very hard to stop considering we want hundreds of mega-volts on our 'tower.'  And etc.—Marko

TESLA - HV fence protecting his property? His lab burned down? - Tesla's wireless power system was debunked to my satisfaction by Paul Nicholson: www.abelian.demon.co.uk/tesla-notes/030802.html.  He argues very convincingly that Tesla was wrong and it could never work with useful efficiency over a useful distance.  It would be kilowatts in, picowatts out, the same efficiency as we observe with ordinary radio transmitters and receivers.  If the CSN was a legal document, or written by Tesla's assistant, how come it contains pages of lyrical waxings about the quality of the moonlight in Colorado?—Steve McConner

Transmitting coil - I am trying to build a transmitting coil to transmit electricity from one secondary to another.  Basically what I need to know is as follows,

*what secondary ratio is best for transmitting
*what top load is best for transmitting 
*what type of coil is best for transmitting (like vttc sgtc sstc drsstc exc)
*if I can get the transmitting coil to run off of 2.5kw what can I get from the receiving coil
*what specs should the receiving coil have—Alex McCown

So okay you have 50% out from what you started with right? Well, kinda not really. See the power drops off as a function P ~ 1/r^2, so you lose your power as an inverse square law proportion. That means at 1 meter you have your 50% recoverable, but at 2 meters you have ~12.5% recoverable because your power drops off by a factor of 4 @ 2 meters distance. Well it gets worse yet. To recover your power at 1 or 2 meters means you need as stated, an identical tuned system, which means that system is matched for another 50% loss, so at 2 meters the maximum power transfer from system A to system B is 6.25%.—Member, ID #135

I’ve always thought that two matched grounded tesla coil transfer only minimum energy via the air (and actually these are unwanted losses) and most of the energy is transferred via the earth (works as a single wire). So the power losses rising with the square of the distance are so dramatic only in case of non-grounded systems… But maybe I’m completely wrong – that’s only my idea how this energy transfer works and why the coils must be grounded to be a good power transmitter…—Member #1025

Antennas and radiation - some questions... - . . . Well yes, an antenna does resonate like a Tesla coil.  Putting toploads on the ends of a dipole will indeed change its resonant frequency, except antenna guys prefer to call them capacity hats.  And all the other changes you mentioned affect the resonant frequency too.  And a Tesla coil is a transmission line whose resonant frequency does depend on its wire length.  The relationship is just pretty complex, because the capacitive and inductive couplings between turns modify the behaviour of the wave: it doesn't just travel straight along the wire and back as it would in a dipole antenna.  If you like, to an extent the wave can take shortcuts through the inter-turn couplings, so the measured resonant frequency ends up higher than you would predict if the wire were just 1/4 of a wavelength.  The only difference is that the radiation resistance of a Tesla coil is negligible compared to its characteristic impedance, so it radiates practically no power and has a very high Q.  A good antenna has a radiation resistance not too different from its feedpoint impedance, hence a low Q, or a broad bandwidth.  In other words, a Tesla coil is a lousy antenna, and an antenna is a poorly designed Tesla coil that's no good at making sparks.—Steve McConner

The energy transmission of the tesla coil - I going to try to build another LC-circuit as receiver.  I hope this will work.  Updates about the results will arrive shortly.—Member, ID #1975

Creation date: 2/21/2009