View Full Version : Wireless power transmission at 6.4 MHz
k4kyv
11-16-2006, 12:02 AM
6.4 MHz has been proposed for wireless power transmission to low-power devices such as computer peripherals. Like BPL, they claim it to be "non radiating." It is clear of the ham bands for now, but there has been talk of extending the 40m band downwards to steer clear of the SWBC stations.
http://news.bbc.co.uk/2/hi/technology/6129460.stm
w8cbc
11-16-2006, 12:12 AM
6400 kc is in the middle of a marine band.
It's a nice idea (that may or may not bear fruit) but don't use it on a ship. http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif
W5HTW
11-16-2006, 12:28 AM
Wake up, Nicholai, your time has come!
Marin Soljacic completed his Ph.D. in 2000 and remained at MIT teaching and doing research projects on optics, light and how waves move through crystal structures. He has written some papers on fractals in crystalline structures and holds several patents related to that. I have read some of his papers. He is a bright guy, however has no industry experience outside of the academic world and has apparently not dealt with RF propagation. Part of the idea behind his theory of charging batteries via a 6.4 MHz electromagnetic wave is that the signal would not leave the charging coil, "except" to jump over to the reception coil of the device being charged. When there was no device to be charged or the charging cycle was complete, the RF energy field would remain contained in the charging coil like a re-circulating hot water system.
Since he has experimentally delayed light propagation and contained it within a crystalline structure he feels that this 6.4 MHz energy, thru a delaying method and a circulating device, will hang around and not radiate. Radio amateurs know that grandpa's bed springs will radiate, sometimes a very long distance. HF is quite different to manage than light. I have severe reservations about his theory. I e-mailed him about my reservations and asked him to expand on his theory and justify it. Lets see if he will respond.
73,
Terry, K7FE
Didn't Tesla transmit electricity through the air?
Yes, Tesla transmitted energy with a great deal of what would be called "interference" today. He wanted to use frequencies that were not really in use then, but are now and his efficiencies were terrible. Tesla is a very interesting inventor.
During the mid 70's I worked on a study for NASA to transmit energy between two narrow points. NASA wanted to transmit energy from space to earth, if possible. The model was to collect energy with Gallium Arsenide or Indium Phosphide solar cells, convert it to microwave energy, transmit it over a distance, collect it and convert it back to a usable energy form, which, for the test was 120VAC 60 Hz. We set up at the NASA Deep Space antenna test range at Goldstone, CA and proved that it worked. It was not practical however, to transmit point to point, multi gigawatt energy through our atmosphere because of the hazard to migratory birds and Cessna's that strayed from their flight plan. Refractions from rain, cloud moisture content, meteors and dust storms also created concerns for humans.
I believe that Dr. Soljacic's idea is impractical also and I question the theory of it working.
73,
Terry, K7FE
w8cbc
11-16-2006, 04:06 PM
I remember the solar power satellite idea was quite the rage for awhile.
I like it but as you say there are too many things to go wrong.
ka5piu
11-18-2006, 04:05 AM
Hello.
I have read the research on a "loaded tank coil".
My question is, why not one of the already allocated ISM freqs?
I see nothing wrong with it on 11 meters.
KI4ITV
11-18-2006, 05:55 AM
Quote[/b] (ka5piu @ Nov. 17 2006,16:05)]Hello.
I have read the research on a "loaded tank coil".
My question is, why not one of the already allocated ISM freqs?
I see nothing wrong with it on 11 meters.
Like you, I don't think anyone would notice the extra interference on 11m. Go for it. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif
NN4RH
11-18-2006, 12:48 PM
Here is some better information than that dumb newspaper article:
http://www.aip.org/ca/2006/soljacic.html
http://arxiv.org/ftp/physics/papers/0611/0611063.pdf
http://www.mit.edu/~soljacic/
This is NOT as kooky as what that news article leads you to believe.
Maybe it would not be practical or cost-effective, but it appears to work out theoretically.
Where it comes to matters of theoretical physics, I'd be inclined to give the benefit of the doubt to the theoretical physicist, over hams basing their opinions on a loosely written newspaper article and dipoles & Tesla on their minds!.
ka5piu
11-18-2006, 01:50 PM
Hello.
It is not "kooky" at all.
In the 70's I was playing around with superconductors and the
ringing osc' idea.
That idea says that if a conductor has NO loss a loop of current should be able to keep the loop forever.
The trouble is that there is loss as the thing would radiate as well as the fact that superconductors are not perfect conductors.
My briefcase communicator is somewhat like a tesla coil but with a solid state unit in place of mechanical contacts and some really good capacators.
I can put out nearly 140000 watt-seconds of power out for 3 full cycles at 175 KHz.
It can be tuned for 98 KHz to 22 MHz with change of element (secondary of coil).
And, it can fry just about anything electronic that is within 15 feet of it.
I use it around 1 watt for the free band at 1750 meters.
The BPL geniuses said that the radiation would not leave the wires and cause interference. Look what happened. That's what RF does. Diathermy, MRI and industrial heating are wonderful for those who need it, however they all must be shielded to prevent that application from interfering with others.
Charging batteries with a coil is done all the time. Look at electric tooth brushes and how they are charged with a 60 Hz field using an inductive pickup in the base. Today, one could use a higher frequency like 6.4 MHz for a larger charging field in a controlled environment that was properly shielded, say a factory. The average home is out of the question.
73,
Terry, K7FE
NN4RH
11-19-2006, 04:12 PM
Read the actual paper at the link I posted.
This is not what everyone is assuming it is.
ab8ro
11-20-2006, 02:06 AM
Quote[/b] (NN4RH @ Nov. 18 2006,10:12)]Read the actual paper at the link I posted.
Haha, surely you jest.
kb2vxa
11-20-2006, 09:32 AM
Theoretical physics + technobabble = Star Trek. Leave out the gobbldegook and you have a great sci-fi story and a physicist author sure helps, ask any fan of Issac Asimov. Science fiction often becomes science fact, yesterday's magic is today's science but don't hold your breath, just read and enjoy.
Oh, count me among the Tesla fans, I'm particularly fond of anecdotes about high potential, high frequency, flowing current, a certain electron named Mike R. Farad and his girlfriend Milli Amp.
ka5piu
11-20-2006, 02:43 PM
Quote[/b] (NN4RH @ Nov. 19 2006,09:12)]Read the actual paper at the link I posted.
This is not what everyone is assuming it is.
Hello.
Even in the article it cites Nikola Tesla.
If I set my briefcase tesla coil to 6.4 MHz I would be doing what is suggested.
I still think tesla fried radio is an excellent menu item.
My next project is to build one that will do 6 meters.
52.525 MHz at 140000 watts PEP!
kc7mrq
11-20-2006, 03:43 PM
Quote[/b] (K7FE @ Nov. 15 2006,12:05)]Marin Soljacic completed his Ph.D. in 2000 and remained at MIT teaching and doing research projects on optics, light and how waves move through crystal structures. #He has written some papers on fractals in crystalline structures and holds several patents related to that. #I have read some of his papers. #He is a bright guy, however has no industry experience outside of the academic world and has apparently not dealt with RF propagation. #Part of the idea behind his theory of charging batteries via a 6.4 MHz #electromagnetic wave is that the signal would not leave the charging coil, "except" to jump over to the reception coil of the device being charged. #When there was no device to be charged or the charging cycle was complete, the RF energy field would remain contained in the charging coil like a re-circulating hot water system. #
Since he has experimentally delayed light propagation and contained it within a crystalline structure he feels that this 6.4 MHz energy, thru a delaying method and a circulating device, will hang around and not radiate. #Radio amateurs know that grandpa's bed springs will radiate, sometimes a very long distance. #HF is quite different to manage than light. #I have severe reservations about his theory. #I e-mailed him about my reservations and asked him to expand on his theory and justify it. #Lets see if he will respond. #
73,
Terry, K7FE
Terry,
Were you the same group that had a SR-71 fly through the beam while transmitting at full capacity?
I spent three years at Ft. Irwin and heard a lot of urban legends about Goldstone.
However, I did see the air ionize above the 70m dish one night.
Corey
Didn't one of the Amateur magazines do an article on this subject and then have to do a retraction when the science didn't hold up?
ka5piu
11-21-2006, 01:10 AM
Hello.
I myself would like to see what the response is.
At 6.4 MHz with freshly wound coils, the primary could not go that high, running 100 milliwatts the thing gets out just fine.
At 52.525 MHz running 100 milliwatts the unit is totally stable
SWR is well within what it needs to be.
A tesla coil is most effective when discharging into something.
Auto sound systems have always been a target.
Quote[/b] (kc7mrq @ Nov. 20 2006,07:43)]
Terry,
Were you the same group that had a SR-71 fly through the beam while transmitting at full capacity?
I spent three years at Ft. Irwin and heard a lot of urban legends about Goldstone.
However, I did see the air ionize above the 70m dish one night.
Corey
Corey,
Thank you for serving.
Some things can be neither confirmed or denied.
There was a great deal of testing on a number of platforms with respect to RF and EMP.
Varian provided the highest power microwave tubes available at that time. As I remember, the tubes cost about $750,000 each in the 1970's. A 210 foot dish is quite a sight when it rotates.
73,
Terry, K7FE
ka5piu
11-24-2006, 07:18 PM
Hello.
Has anyone else tried the Tesla coil power thing?
Early radio had the coherer thing going, a bit of metal filings and what is in essence an electric bell clapper.
Tesla tried to send power with a tuned RF coil.
Now, with the latest in modern semiconductors we have someone wanting to do the same thing all over again.
But, the question remains, who else is tinkering with the Tesla coil?