NEWS: Physics promises wireless power

<http://news.bbc.co.uk/2/hi/technology/6129460.stm>:

The tangle of cables and plugs needed to recharge today's electronic
gadgets could soon be a thing of the past.

US researchers have outlined a relatively simple system that could
deliver power to devices such as laptop computers or MP3 players
wirelessly.

The concept exploits century-old physics and could work over
distances of many metres, the researchers said.

Although the team had not built and tested a system, computer models
and mathematics suggest it would work.

"There are so many autonomous devices such as cell phones and
laptops that have emerged in the last few years," said Assistant
Professor Marin Soljacic from the Massachusetts Institute of
Technology and one of the researchers behind the work.

"We started thinking, 'it would be really convenient if you didn't
have to recharge these things'.

"And because we're physicists we asked, 'what kind of physical
phenomenon can we use to do this wireless energy transfer?'."

Energy trap

The answer the team came up with was "resonance", a phenomenon that
causes an object to vibrate when energy of a certain frequency is
applied.

"When you have two resonant objects of the same frequency they tend
to couple very strongly," Professor Soljacic told the BBC News
website.

Resonance can be seen in musical instruments for example.

"When you play a tune on one, then another instrument with the same
acoustic resonance will pick up that tune, it will visibly vibrate,"
he said.

Instead of using acoustic vibrations, the team's system exploits the
resonance of electromagnetic waves. Electromagnetic radiation
includes radio waves, infrared and x-rays.

Typically, systems that use electromagnetic radiation, such as radio
antennas, are not suitable for the efficient transfer of energy
because they scatter energy in all directions, wasting large amounts
of it into free space.

To overcome this problem, the team investigated a special class of
"non-radiative" objects with so-called "long-lived resonances".

When energy is applied to these objects it remains bound to them,
rather than escaping to space. "Tails" of energy, which can be many
metres long, flicker over the surface.

"If you bring another resonant object with the same frequency close
enough to these tails then it turns out that the energy can tunnel
from one object to another," said Professor Soljacic.

Hence, a simple copper antenna designed to have long-lived resonance
could transfer energy to a laptop with its own antenna resonating at
the same frequency. The computer would be truly wireless.

Any energy not diverted into a gadget or appliance is simply
reabsorbed.

The systems that the team have described would be able to transfer
energy over three to five metres.

[MORE]

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John Navas <(E-Mail Removed)> wrote:

> <http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>
> The tangle of cables and plugs needed to recharge today's electronic
> gadgets could soon be a thing of the past.
>
> US researchers have outlined a relatively simple system that could
> deliver power to devices such as laptop computers or MP3 players
> wirelessly.
>
> The concept exploits century-old physics and could work over
> distances of many metres, the researchers said.

<snip>

> [MORE]

http://en.wikipedia.org/wiki/Nikola_Tesla

"John Navas" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> <http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>
<snip>
> "And because we're physicists we asked, 'what kind of physical
> phenomenon can we use to do this wireless energy transfer?'."
>
> Energy trap
>
> The answer the team came up with was "resonance", a phenomenon that
> causes an object to vibrate when energy of a certain frequency is
> applied.
>
> "When you have two resonant objects of the same frequency they tend
> to couple very strongly," Professor Soljacic told the BBC News
> website.

Reminds me of the rumored weapon "Hammer of Thor" to be used in warfare this
decade.

From a high flying altitude, a directed particle beam could be focused
tightly enough to reduce a human to a puddle of fat and grease >while inside
a car< in a few seconds.

We could combine cell phones and directed energy to eliminate California
high speed auto chases. ;-)

John Navas <(E-Mail Removed)> hath wroth:

><http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>
> US researchers have outlined a relatively simple system that could
> deliver power to devices such as laptop computers or MP3 players
> wirelessly.
>
> The concept exploits century-old physics and could work over
> distances of many metres, the researchers said.
(...)

Yawn. Basically, they're building a resonant RF transformer. Coupling
efficiency is maximum at resonance so that makes sense. However it's
still radio waves and physics limits what can be done at their chosen
frequency of 6.4MHz. There's no "wave magnet" available in radio
waves. We're working in the near field where field strength varies
roughly linearly with the distance. Double the distance and lose half
the power. At the claimed 5 meters range, there's very little RF
available to charge the device. My guess is about 5% efficiency
depending on coil size. I guess energy conservation is of little
concern because to deliver typical charger power, a substantial amount
of RF must be radiated and lost to nowhere in particular. The device
also has to have a relatively high Q coupling coil in order to work.
That's difficult to do in a small package and will be seriously
detuned by body capacitance. Want more delivered power? Get a bigger
coil. Want gross inefficiency? Use a small coil.

The inability to direct the RF will also causes problems. Much of the
6.4MHz signal will get into the cell phone or radio, mix well, and get
served as intermod, rectification, and other unwanted circuit
malfunctions. Shielding will probably be necessary.

What does make this potentially practical is that the power
consumption of portable devices are dropping rapidly. Chances are
slim that they can meet FCC Part 15 radiation requirements and still
deliver useable amounts of RF, but that can be negotiated (or ignored
as in BPL).

While useless for delivering substantial amounts of power, resonant
transformer coupling might be suitable for small loads, and only if
one doesn't care about efficiency.

Incidentally, the 6.4MHz area is straddled by marine SSB and GMDSS
users. I'm sure they'll be thrilled with the new source of RF
pollution.

Ok, bring on the investors.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In alt.cellular.cingular John Navas <(E-Mail Removed)> wrote:
> <http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>

I remember seeing this done with florescent light bulbs. It was an inspiring
demonstration for elementary school students in the 70s.

There are issues of concern. In the United States, electricity is transferred
in the power grid at 60Hz. 60Hz also corresponds to the frequency of the
Lithium Ion (Li+). It has been shown that lithium ions will leave the skin of
a human being when exposed to this frequency for an extensive period of time.
Some have hypothesized that this may cause depression issues in some people,
and others have suggested it may cause cancer. I recall this issue years ago,
but it has been largely squashed; however, I was able to find this one
resource:

http://oaspub.epa.gov/eims/eimscomm....load_id=437194

Now, my question is whether this same effect might exist when using a Tesla
coil (that is how this is accomplished). I don't see why it wouldn't. I
suspect that to alleviate concerns, they will have to find a frequency that
they "determine" is safe and tool standardization along that path.
Personally, I think that it is a bad idea from a health perspective and
shouldn't be done without many decades of testing on animals. I would hate to
be that pig.

--
Thomas T. Veldhouse
Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0

On Wed, 15 Nov 2006 18:23:03 GMT, "Thomas T. Veldhouse"
<(E-Mail Removed)> wrote in
<bWI6h.2721$(E-Mail Removed)>:

>In alt.cellular.cingular John Navas <(E-Mail Removed)> wrote:
>> <http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>
>I remember seeing this done with florescent light bulbs. It was an inspiring
>demonstration for elementary school students in the 70s.
>
>There are issues of concern. In the United States, electricity is transferred
>in the power grid at 60Hz. 60Hz also corresponds to the frequency of the
>Lithium Ion (Li+). It has been shown that lithium ions will leave the skin of
>a human being when exposed to this frequency for an extensive period of time.
>Some have hypothesized that this may cause depression issues in some people,
>and others have suggested it may cause cancer. I recall this issue years ago,
>but it has been largely squashed; however, I was able to find this one
>resource:
>
>http://oaspub.epa.gov/eims/eimscomm....load_id=437194
>
>Now, my question is whether this same effect might exist when using a Tesla
>coil (that is how this is accomplished). I don't see why it wouldn't. I
>suspect that to alleviate concerns, they will have to find a frequency that
>they "determine" is safe and tool standardization along that path.
>Personally, I think that it is a bad idea from a health perspective and
>shouldn't be done without many decades of testing on animals. I would hate to
>be that pig.

While your concern is understandable, I think it's overdone -- the
physics make such side effects unlikely.

--
Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas <http://en.wikibooks.org/wiki/Cingular_Wireless_FAQ>

On Wed, 15 Nov 2006 10:14:22 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>John Navas <(E-Mail Removed)> hath wroth:
>
>><http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>>
>> US researchers have outlined a relatively simple system that could
>> deliver power to devices such as laptop computers or MP3 players
>> wirelessly.
>>
>> The concept exploits century-old physics and could work over
>> distances of many metres, the researchers said.
>(...)
>
>Yawn. Basically, they're building a resonant RF transformer. [SNIP]

I respectfully suggest you actually read the research instead of making
assumptions and leaping from them to all those conclusions.

--
Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas <http://en.wikibooks.org/wiki/Cingular_Wireless_FAQ>

Jeff Liebermann wrote:

> What does make this potentially practical is that the power
> consumption of portable devices are dropping rapidly.

At the lower power levels, solar becomes practical as well, it's already
used on a lot of calculators. I had a bicycle computer that worked on
solar, and an old Sony Walkman (cassette) that used solar to charge an
internal NiCad.

Powering a laptop computer would be a real accomplishment, I wouldn't
hold my breath waiting for that to happen.

John Navas <(E-Mail Removed)> hath wroth:

>On Wed, 15 Nov 2006 10:14:22 -0800, Jeff Liebermann
><(E-Mail Removed)> wrote in
><(E-Mail Removed)>:
>
>>John Navas <(E-Mail Removed)> hath wroth:
>>
>>><http://news.bbc.co.uk/2/hi/technology/6129460.stm>:
>>>
>>> US researchers have outlined a relatively simple system that could
>>> deliver power to devices such as laptop computers or MP3 players
>>> wirelessly.
>>>
>>> The concept exploits century-old physics and could work over
>>> distances of many metres, the researchers said.
>>(...)
>>
>>Yawn. Basically, they're building a resonant RF transformer. [SNIP]
>
>I respectfully suggest you actually read the research instead of making
>assumptions and leaping from them to all those conclusions.

What research? There's no link. I did read the BBC article and found
it entertaining as I do enjoy reading science fiction. I also
indicated that it might be useful if the device being charged consumed
very little power. I do the math for resonant coupling for you if you
want. Give me a frequency, distance, and delivered power requirement
and I'll calculate the size of the coils, coupling efficiency, and
approximate radiation. No research required as it's in any
electronics textbook that covers RF xformers.

What is unique is this section:
To overcome this problem, the team investigated a special class
of "non-radiative" objects with so-called "long-lived resonances".

When energy is applied to these objects it remains bound to them,
rather than escaping to space. "Tails" of energy, which can be many
metres long, flicker over the surface.

"If you bring another resonant object with the same frequency close
enough to these tails then it turns out that the energy can tunnel
from one object to another," said Professor Soljacic.

I've never heard of this phenomenon and would be genuinely interested
in reading the research report. Last time I checked, there's no such
thing as a static or potential RF field but I'm open to new ideas. It
might be done with superconductors, where the field isn't dampened,
but not on a piece of wire.



--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

SMS <(E-Mail Removed)> hath wroth:

>Powering a laptop computer would be a real accomplishment, I wouldn't
>hold my breath waiting for that to happen.

Minor trivia: Ever wonder how much power your laptop sucks? No need
to measure it. Just look at the rating on the battery charger.
Multiply volts times amps to get watts. The idea is that the battery
charger is suppose to run the laptop with the battery removed. It can
only do that if it has sufficient power capacity. Most of mine are
around 40 watts. However, I've seen Toshiba desktop replacements with
120 watt power adapter and blow enough hot air to suspect all of it is
being used.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558