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Chris Barrett

Posted: Fri Jun 08, 2007 4:06 am

Guest

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

Guest

Posted: Fri Jun 08, 2007 10:25 am

Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

Quote:

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.

--
Jim Pennino

Remove .spam.sux to reply.

Chris Barrett

Posted: Sat Jun 09, 2007 10:05 pm

Guest

jimp@specsol.spam.sux.com wrote:

Quote:

Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.

So is there zero hope that this technology could ever power automobiles?

Guest

Posted: Sat Jun 09, 2007 10:15 pm

Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

Quote:

jimp@specsol.spam.sux.com wrote:
Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.

So is there zero hope that this technology could ever power automobiles?

I'd say that there is zero hope that this technology will ever power
anything real.

--
Jim Pennino

Remove .spam.sux to reply.

Wimpie

Posted: Mon Jun 11, 2007 11:15 am

Guest

On 8 jun, 11:06, Chris Barrett
<"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

Quote:

Hello Chris,

Yes, it can be efficient. Probably it is a two resonator critically
coupled Band Pass Filter (as used in for example radio equipment).
Some people know them from passive (crystal detector) radio
circuits.

With respect to radiation there are two things to consider: when it is
less then 1%, the effect on efficiency is acceptable (negligible),
however, when is it 1% or less, it is about 0.6W (60W transferred
power), you probably will be visited by some representatives of the
telecom administration...

The amount of radiated power depends heavily on the frequency used
(and possible harmonics). Some figures:

When you run 100A (1 MHz) through one circular turn with D = 3ft
(0.91m), the radiated power will be about 17 mW (because of the H-
field). When the frequency is 3 MHz, same coil, same current, the
radiated power will be 1.34W. The radiation loss and other losses
can increase significantly when the field couples with other
structures. This is well known to people working in RF EAS (Electronic
Article Surveillance) and RF RFID.

When the energy transfer is 60W over about 6ft distance, I can hardly
imagine that you stay below INCIRP guidelines. The reason is that the
magnetic flux linkage between the two coils will be very low, so you
need a high Q factor for both tuned circuits, resulting in high
circulating current in the coils.

As the flux linkage between two widely separated coils falls of with
r^3. The efficiency can be increased significantly by reducing the
distance a little bit.

Best regards,

Wim
PA3DJS

Wimpie

Posted: Mon Jun 11, 2007 11:25 am

Guest

On 10 jun, 05:15, j...@specsol.spam.sux.com wrote:

Quote:

Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:
j...@specsol.spam.sux.com wrote:
Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.
So is there zero hope that this technology could ever power automobiles?

I'd say that there is zero hope that this technology will ever power
anything real.

--
Jim Pennino

Remove .spam.sux to reply.
Hello Jim,

I am not sure that this kind of technology will not be used. It can be
a very nice way to transfer energy without electrical contact (over
small distance). There will be no contact wear and no risk of electric
shock.

For 2 years ago I was hired as a consultant to setup a demonstrator
for inductive power transfer (for charging batteries, it was
successfully). The technology is also investigated for power transfer
between mains supply and car battery in electric powered vehicles.

When the distance between transmitting and receiving coil is small
with respect to the diameter of the coil (and/or magnetic core), the
efficiency increases significantly.

Best regards,

Wim
PA3DJS

Guest

Posted: Mon Jun 11, 2007 11:55 am

Wimpie <wimtel@tetech.nl> wrote:

Quote:

On 10 jun, 05:15, j...@specsol.spam.sux.com wrote:
Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:
j...@specsol.spam.sux.com wrote:
Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.
So is there zero hope that this technology could ever power automobiles?

I'd say that there is zero hope that this technology will ever power
anything real.

--
Jim Pennino

Remove .spam.sux to reply.
Hello Jim,

I am not sure that this kind of technology will not be used. It can be
a very nice way to transfer energy without electrical contact (over
small distance). There will be no contact wear and no risk of electric
shock.

For 2 years ago I was hired as a consultant to setup a demonstrator
for inductive power transfer (for charging batteries, it was
successfully). The technology is also investigated for power transfer
between mains supply and car battery in electric powered vehicles.

When the distance between transmitting and receiving coil is small
with respect to the diameter of the coil (and/or magnetic core), the
efficiency increases significantly.

Yes, this is called a transformer and is how cordless, electric
toothbrushes are charged and not the same thing.

There have been numerous schemes devised to transformer power vehicles.

None of them stand up to reality.

--
Jim Pennino

Remove .spam.sux to reply.

Don Kelly

Posted: Mon Jun 11, 2007 11:12 pm

Guest

----------------------------
<jimp@specsol.spam.sux.com> wrote in message
news:fo6sj4-8b1.ln1@mail.specsol.com...

Quote:

Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:
jimp@specsol.spam.sux.com wrote:
Chris Barrett <"chrisbarret"@0123456789abcdefghijk113322.none> wrote:

I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance.
Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

No and yes.

Not to mention the immense RFI problems of such a device which would
make it basically illegal in most of the world unless a spot
frequency was designated for it and the frequency, harmonics,
etc. were tightly controlled.

And the idea is not new, Tesla screwed around with this sort of stuff
for years.

So is there zero hope that this technology could ever power automobiles?

I'd say that there is zero hope that this technology will ever power
anything real.

--
Jim Pennino

Remove .spam.sux to reply.
----------

My old crystal set- which proves your point in a roundabout way. Of course,
if I want to power my car, I would have to be receiving several Kw all the
time I was on the road and a 4 hour trip should be sufficient to cook all
the turkeys in the vehicle. It would be much more efficient to crawl into
a large microwave or conventional oven to accomplish the same objective.
Self regulating process- fry the users gonads and other bits and pieces and
the human demand for energy would drop to a very low level making way for
cockroaches to develop the next civilisation. --

Don Kelly dhky@shawcross.ca
remove the X to answer

Bill Miller

Posted: Tue Jun 12, 2007 6:10 pm

Guest

"Wimpie" <wimtel@tetech.nl> wrote in message
news:1181578526.825728.88900@n4g2000hsb.googlegroups.com...

Quote:

On 8 jun, 11:06, Chris Barrett
"chrisbarret"@0123456789abcdefghijk113322.none> wrote:
I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

Hello Chris,

Yes, it can be efficient. Probably it is a two resonator critically
coupled Band Pass Filter (as used in for example radio equipment).
Some people know them from passive (crystal detector) radio
circuits.

With respect to radiation there are two things to consider: when it is
less then 1%, the effect on efficiency is acceptable (negligible),
however, when is it 1% or less, it is about 0.6W (60W transferred
power), you probably will be visited by some representatives of the
telecom administration...

The amount of radiated power depends heavily on the frequency used
(and possible harmonics). Some figures:

When you run 100A (1 MHz) through one circular turn with D = 3ft
(0.91m), the radiated power will be about 17 mW (because of the H-
field). When the frequency is 3 MHz, same coil, same current, the
radiated power will be 1.34W. The radiation loss and other losses
can increase significantly when the field couples with other
structures. This is well known to people working in RF EAS (Electronic
Article Surveillance) and RF RFID.

When the energy transfer is 60W over about 6ft distance, I can hardly
imagine that you stay below INCIRP guidelines. The reason is that the
magnetic flux linkage between the two coils will be very low, so you
need a high Q factor for both tuned circuits, resulting in high
circulating current in the coils.

As the flux linkage between two widely separated coils falls of with
r^3. The efficiency can be increased significantly by reducing the
distance a little bit.

Best regards,

Wim
PA3DJS

A few additional thoughts...

Imagine what might happen if someone with an implanted pacemaker or
defibrilator came near to a field strong enough to light a 60 W bulb!

We also have any number of "environmentalists" that are convinced that high
tension power cables cause everything from cancer to glaucoma (which can, of
course, be cured by smoking pot). And this group usually has LAWYERS that
will tie everything up in knots for years while the effect of RF on the
green-toed gecko (endangered, of course -- it is the primary food of the
spotted owl) is studied.

Technically, the power source would have to be free of harmonics. Otherwise,
every TV in the neighborhood becomes unusable. Not to mention the probable
disruption to bonafide radio frequency spectrum users as radio amateurs,
first responders, military and service providers. Even if it is
harmonic-free, non-linear devices within the field are likely to rectify the
power source and re-radiate harmonics. Same effect.

Bill Miller
(KT4YE)

Wimpie

Posted: Wed Jun 13, 2007 4:29 am

Guest

On 13 jun, 01:10, "Bill Miller" <BillMillerKT...@worldnet.att.net>
wrote:

Quote:

"Wimpie" <wim...@tetech.nl> wrote in message

news:1181578526.825728.88900@n4g2000hsb.googlegroups.com...

On 8 jun, 11:06, Chris Barrett
"chrisbarret"@0123456789abcdefghijk113322.none> wrote:
I read an article yesterday. It talked about scientists transmitting
energy wirelessly by using some kind of electromagnetic resonance. Here
is a link to the article:

http://news.bbc.co.uk/2/hi/technology/6725955.stm

My question: can this process by efficient? Wouldn't this invention
radiate a very large fraction of its energy out into space?

Hello Chris,

Yes, it can be efficient. Probably it is a two resonator critically
coupled Band Pass Filter (as used in for example radio equipment).
Some people know them from passive (crystal detector) radio
circuits.

With respect to radiation there are two things to consider: when it is
less then 1%, the effect on efficiency is acceptable (negligible),
however, when is it 1% or less, it is about 0.6W (60W transferred
power), you probably will be visited by some representatives of the
telecom administration...

The amount of radiated power depends heavily on the frequency used
(and possible harmonics). Some figures:

When you run 100A (1 MHz) through one circular turn with D = 3ft
(0.91m), the radiated power will be about 17 mW (because of the H-
field). When the frequency is 3 MHz, same coil, same current, the
radiated power will be 1.34W. The radiation loss and other losses
can increase significantly when the field couples with other
structures. This is well known to people working in RF EAS (Electronic
Article Surveillance) and RF RFID.

When the energy transfer is 60W over about 6ft distance, I can hardly
imagine that you stay below INCIRP guidelines. The reason is that the
magnetic flux linkage between the two coils will be very low, so you
need a high Q factor for both tuned circuits, resulting in high
circulating current in the coils.

As the flux linkage between two widely separated coils falls of with
r^3. The efficiency can be increased significantly by reducing the
distance a little bit.

Best regards,

Wim
PA3DJS

A few additional thoughts...

Imagine what might happen if someone with an implanted pacemaker or
defibrilator came near to a field strong enough to light a 60 W bulb!

We also have any number of "environmentalists" that are convinced that high
tension power cables cause everything from cancer to glaucoma (which can, of
course, be cured by smoking pot). And this group usually has LAWYERS that
will tie everything up in knots for years while the effect of RF on the
green-toed gecko (endangered, of course -- it is the primary food of the
spotted owl) is studied.

Technically, the power source would have to be free of harmonics. Otherwise,
every TV in the neighborhood becomes unusable. Not to mention the probable
disruption to bonafide radio frequency spectrum users as radio amateurs,
first responders, military and service providers. Even if it is
harmonic-free, non-linear devices within the field are likely to rectify the
power source and re-radiate harmonics. Same effect.

Bill Miller
(KT4YE)

Hi Bill,

It is likely that interference will occur in electronic equipment
(including medical implants).

Some additional figures.

2 single turn coils with D = 2ft (0.91m) and 6.5ft distance (2m) will
have a flux linkage (k) of about 7.8m. When the coils are made of very
thick wire (tube), the inductance will be about 1.3uH.

The loaded Q factor for critically coupled BPF shall be around 128 (1/
Q). This means when you want to transfer 60W, the blind power (VAR)
for the coils will be around 7.7kW.

Let assume that we are using 600 kHz (so inductor impedance is j5
Ohm), then the inductor current must be about 40A (about 200V across
the inductor).

When you are sitting 2ft (0.6m) from a single turn coil with D = 3ft
(0.9m) and carrying 40A rms, the undisturbed H-field will be about 17A/
m (equivalent to 21 uT). The ICNIRP reference level for the general
public at 600 kHz is 1.5uT.

So at 0.6m, you exceed the reference level for 600 kHz with factor 14
(23 dB). I think it will be difficult to prove that you do not exceed
the basic restriction. In addition, when you are more close to the
coil, the field strength does increase significantly. EMC
susceptibility testing is done on far lower values (then he INCIRP
reference levels)

Of course 600 kHz is far away from the band of interest for a
peacemaker or ICD (Implantable Cardioverter Defibrillator), but I
would not stay there when my life depends on such a device.

One can reduce the near field levels by reducing the distance between
the coils as the flux linkage factor (k, is proportional to about 1/
distance^3). In that case the current through the coils can be
significantly lower to transfer the same 60W.

EMC is an issue with such devices as far field radiation from coils is
proportional with f^4. Because of efficiency one must use switching
electronics (lots of harmonics, so good filtering required). Also the
rectification (when DC is required) will introduce harmonics, and, as
you mentioned, nearby structures may generate harmonics also (as is
used in certain detectors).

Best regards,

Wim
PA3DJS
www.tetech.nl

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