wireless transmittion of power

Incredibly inefficient. You can theoretically transmit rf energy just like any radio station does, but the conversion of mains frequency (50/60 Hz) power to rf is remarkably inefficient. Further, in order to not waste the transmitted energy by broadcasting it, you need a very high gain antenna to keep the beam "focused." That in turn means the microwave band, and conversion of mains power to microwave energy is even more inefficient than say vhf (FM band) energy conversion (losses are much higher).

I'm not sure what the mechanism would be for converting the received microwave band energy back into usable electrical power, unless you were just looking for heat. I expect that energy conversion - to usable electrical power, not heat - would be quite inefficient as well.

This is not to say that this couldn't be done in some specialized cases. RFID works on this principle, at very close range and minute amounts of power. And it has been hypothesized that large space arrays of solar panels could convert solar energy into electrical energy; that energy converted to a beam of microwaves aimed at the earth and the received energy converted into powering the electrical grid. But that scheme assumes essentially unlimited power so that the abysmal efficiency doesn't matter.

You could replace the conversion of rf to optical - a laser, and if you pick the right wavelength, you might get very little transmission loss (line-of-sight), but again the conversion of mains power to laser power and back is very inefficient.

And while we are fantasizing about things that will never be, keep in mind the outrage that would ensue from birds being cooked as they flew into the rf or laser beam. Literally. If enough energy was being transmitted to make it commercially viable (ignoring the efficiency issue) the power density in the beam would greatly exceed that in your microwave oven.

Arrggghhh NO ... not this question again.
It has been discussed umpteen times.
It's a bad idea...search the site for other discussions if you really want the detail.

Come to think of it 'wireless anything' is a bad idea as the reliability is usually pants
Del

Power is transfered in a transformer with no direct wire connection.

If you however move the 2 coils apart the transfered power becomes less very fast.

With radio waves the transmitted power at the receiving end is very weak and need to be amplified to be of any uses.

The older generation like me played with crystal / diode radios. they worked exclusively on transmitted power.

So transmitting is possible. But it is nowhere close enough for getting useful power available at the other end.

You are also not alone in wondering. The books "The Standard University" published in 1935 were exited about the possibility running a bus or a train on transmitted power. To be honest I think the also said that it is not viable.

Unless somebody invents an improved beam the transmission of bulk power will stay a dream.

Maybe someone will create a SS Enterprise transporter to beam the coal to another place where it can be burned for power.

I don't know yet but the subject has been a burning issue in my mind for quite a long time. I agree with the answers above that no meaningful output will be realised at the other end using the existing relevant technologies at the moment, but this dream should not die. I hope it will be realised someday and I predict so. Remember, "Everything you can imagine is real" ...Pablo Picasso

Cheers,

ethobil

Not an expert on art history (understatement of the year, so far) but the following quotation: "Everything you can imagine is real," has to rank up there in the top ten stupidest statements ever made. Ever.

Just about everyone dreams they can fly, like a bird. The ancient Greeks enshrined that longing in the myth of Daedalus and Icarus. I can imagine putting ice cubes in a glass and having them sink to the bottom.

No human will ever fly like a bird, and ice is less dense than water.

Likewise antennas are the devices used to transduce electrical energy in a guided wave or transmission line into a traveling electromagnetic wave and vice versa. Antennas are conceptually simple devices and the fundamentals are well understood. It's basic high school geometry. And the equations that explain path loss between a transmitter and a receiver are high school algebra. Nothing is going to change here because nothing can change.

The usefulness of the human mind as a tool is in direct proportion to how well the mind understands and mirrors the nature of reality. When the correlation is high, progress is made. When the correlation is low, stagnation results.

Prior to Copernicus, mankind had a geocentric view of the universe, and a working model that predicted eclipses and the like. Recall the story of Columbus predicting an eclipse to frighten some hostile Indians (native Americans) in the late 1400s. That was based on pre-Copernican theory, and it was accurate enough to cause awe and consternation in the Indians. But the theory was entirely empirical. It was like curve fitting data whose fundamental nature is not understood. You can do it, and it works, at least until another errant data point shows up. But with the advent of the heliocentric model, the observations of Tycho Brahe and the three laws of planetary motion deduced from those measurements by Johannes Kepler, Isaac Newton was able to deduce the true nature of planetary motion based on gravity. That insight led to all sorts of predictions and discoveries of things not yet observed, because it was a high fidelity model of how things worked.

And three centuries later when technology had progressed to the point where certain Newtonian predictions were found to not quite measure up to observed reality, it became the impetus for the next great shift in human understanding of how the universe works, the general theory of relativity.

Reality exists, independent of our consciousness of it. Our "imagination" and consciousness and perceptions are useful only to the extent that they accurately mirror reality. The fun house mirror distortion of a drug-addled mind is of absolutely no use whatsoever, else we would have wondrous inventions indeed since the 1960s.

Likewise the longings for quick fixes to pressing problems by uninformed minds do not translate into solutions. Mankind labored for a thousand years to find the philosophers' stone, the magic invention that would change base metals into gold. The advent of the true science of chemistry slowly supplanted the alchemy of old, and eventually chemists and nuclear physicists were indeed able to change lead into gold. Mind you in a cyclotron and at a cost greatly exceeding the value of the gold created, but the problem was solved once the underlying nature of the elements was understood.

You can believe anything you want, but when you step out of an airplane at several thousand feet altitude, what happens next depends on whether or not your chute opens, no matter what you believe in, and no matter how deeply you believe.

The universe(s) existed before you were born, and it/they will exist after you die, and it will not make one bit of difference to the natural laws that you existed, or didn't, or that you believed, or didn't.

Extrapolating the Heisenberg uncertainty principle to macroscopic phenomena is a (usually deliberate) and completely fallacious and specious attempt to justify a subjective view of reality. The fact remains that reality is purely objective, and all the belief and wishing and hoping changes nothing until you understand what Sir Francis Bacon enunciated over four centuries ago when he pronounced the death of, and epitaph for, alchemy:

"Nature, to be commanded, must be obeyed."

To which I must sadly add the following corollary which is required four centuries later, but wasn't necessary back in his day:

"Nature, to be obeyed, must be understood."

I think that people are equally divided on the 'mind over matter' issue. I respect you, and within the boundaries expressed by you, everything you say is very accurate.

I only chase this because I've had experiences that require other explanations to be sought. I do not seek to minimize anything you say as scientifically it is well founded, and I know that. the number of people who have been able to show the level of belief necessary to jump chuteless are few. granted. That does not negate the possibility.

It was a book by Richard Feynman (QED) that first described to me how the quantum collapse works. There are other possibilities and theories in these grey areas.

we can agree to disagree.

Chris

I am enthralled by your sense of history and must commend you for that.

Again, i cannot help but agree with most of your comments but still disagree with your view on "Everything you can imagine is real"

This is a motivational statement that encourages keeping good dreams alive with a view to actualising them.

cheers,

ethobil

"...disagree with your view on "Everything you can imagine is real."

This is a motivational statement that encourages keeping good dreams alive with a view to actualising them."

As a motivational statement for human behavior modification, it is important to be able to visualize where you want to go in order to get there. This applies to all manner of human activity, from learning a physical skill to creating wealth. In that sense, as in your post numbered "21", you are correct.

However, there are bounds. If you visualize yourself flying alone like a bird, unaided by any mechanical contraption, that isn't going to happen. Your dreams, if they are to be of use, must constrain themselves within the bounds of objective reality. The Wright Brothers wanted to fly, but they found themselves constrained by both nature and technology. Nature didn't design the human body for flight. The Wrights and others before them understood how to make a wing, but no one until the Wrights could generate enough motive power to get off the ground under their own power. The Wrights essentially redesigned the conventional internal combustion engine of the time in order to generate the horsepower-to-weight ratio that would get them airborne.

This is all summed up in the Serenity Prayer, which is wisdom of the very highest order, whether you pray to a Deity, or not:

God grant me the serenity to accept the things I cannot change; courage to change the things I can; and the wisdom to know the difference.

Wisdom in the sense of understanding the bounds of reality; in the sense of the previous quote from Sir Francis Bacon: "Nature, to be commanded, must be obeyed.". Humans can't fly: we lack wings and enough strength to do so. The wax wings of Icarus wouldn't work even if he hadn't flown too close to the sun: that Dadealus was successful is fanciful thinking and physically impossible.

In the sense of your original post numbered 4, the quote from Picasso, the above modifications very much apply. My interpretation of what you were saying is that even if wireless technology doesn't have a way to transmit electrical grid energy today, you believe and predict it can happen.

There you have to understand the difference between a technological restriction entirely due to the "state-of-the-art," vs. a fundamental limitation, such as how electromagnetic energy is created and controlled and transmitted.

So for instance if you tell me that you can't model a certain physical process because you need ten times the computing power now available in your desktop PC, we can imagine that in a few years that problem will be solved. That is a simple extrapolation of a trend about four decades old. But even there you have to be careful. We are running into very significant technological limitations that are threatening the end of the Moore's Law prediction of doubling transistor density every eighteen months. So even a seemingly simple extrapolation of recent history cannot be made without understanding the science behind the trend.

Not a good example presently, but if you recommend I buy a stock as a sure thing because its value has been rising steadily for several months, you will excuse me if I ask how you know that the trend will continue. If I don't ask that question, then I become the "greater fool."

But when you look at antenna theory at the level I presented it in post #17, that is fundamental physics and is not a technology limitation. You are up against how natural laws work and you can't imagine those away. You have to have the wisdom to accept that.

If you don't, there is no more point have an engineering discussion than if we were arguing about how many angels can dance on the head of a pin. If anything is possible, based on faith and no understanding, then all discussion is a total waste of time.

Very well put, moving actually emc. GA.

Again, you are correct in your assertions

I agree that imagination is bounded by reality. And you will agree that imagination also fires ingenuity. Hence the technological break throughs we have today. That is the premise on which my original post's prediction is confined.

What if new methods of creation and control of electromagnetic energy are discovered and what if these discoveries lead to a possible realisation of that prediction. (these are all possibilities not faith based though )

Cheers,

ethobil

Get an AM radio that harnesses plenty of RF energy (signal) will that be enough?

Someone said 'Not this question again' and may I say he's damn right.

This stupid topic took up a great part of this blog in 2008 and the new year (2009) has just begun meaning that technology hasn't advanced far enough yet.

Otherwise ask MIT!!!

They're the official experimenters of wireless energy transfer since the US gov. took hold of many of Tesla's papers and other interesting articles after his death, and now releasing it to those they flavour (Oops) favour (like MIT and others) to embrace it as their revolutionary new projects.

Isti80,

Thank you for throwing more light on the topic, especially the MIT link.

But I am disagreeing with you that the topic is stupid. It could be said to be a cliche' in this forum but definitely not stupid. The original poster must have acted on the spur of the moment by not consulting previous relevant treads, probably because his imagination was fired up. The thought could as well, have been original to him (not holding brief for the OP, just making a point. Similar thought occurred to me some time ago while doing some pondering on radio transmission)

cheers,

ethobil

NO COMMENT. AGAIN & AGAIN & AGAIN & AGAIN!!!!

Why God???

Hi Hardik Makwana

The wireless reception of energy is is in use around the world, coming from the sun and harnessed by solar collectors both electrical and thermal, and indirectly by wind.

Because of the amount of energy tranmitted and that it is freely available these are becoming economic realities.

However, no one has yet made a safe power ttansmitter of that magnitude.

Maybe Ronald Rayguns star wars death ray.

Yes. cooked birds will fall out of the sky....

Ronald Regan / Ray-gun was a b...t artist himself.

He only tried to scare the former soviet union with his star-war initiatives but it never worked; the Soviets only gave in due to going financially broke.

Anyway, this supposed to be an engineering blog, not a sci-fi one!

Why don't you dreamers go somewhere else and leave this blog in peace so it can continue to focus on more down to earth issues?

Many, many years ago, in US Army radio school in Columbia, South Carolina, an instructor, in order to demonstrate how much power was radiated from a tactical AM radio transmitting antenna, would hold a free standing fluorescent bulb in the vicinity of the antenna. It would glow brightly, as though connected to the mains. This is "free space" energy transfer. However, I do not believe this would prove very practical...

The following is meant to provide background and provoke thought-discussion about alternatives...

The florescent bulb held unsafely close to a high voltage electric transmission line will also glow brightly. So this demonstrates AC changing electrical field intensity exciting the gas in the florescent bulb. The electric field is invisible in air, but there are electric field intensity measurement instruments. At high voltage test facilities a wire cage (usually tubular) around the object under test, is used to uniformly intensify the electric field.

If you take iron filings and spread them thinly on paper and then bring an electric conductor with current flow near the filings you can demonstrate the magnetic field.

If you add a loop iron core with two windings the coupling typicly improves to 90+% efficient between energized primary and output secondary windings in a transformer.

On a free space radiated wave, the ARRL (American Radio Relay League) website has info about transmitters and antenna designs.

If like a solar collector, the output of multiple antennas could be paralleled, and you lived near a clear channel 100,000 watt radio station transmitter antenna, you probably wouldn't have an electric bill. But when you intercept the radio energy there is a "reception dead zone" somewhere behind your array.

So just like the sun provides solar energy, ...

"If like a solar collector, the output of multiple antennas could be paralleled, and you lived near a clear channel 100,000 watt radio station transmitter antenna, you probably wouldn't have an electric bill."

As I stated in an earlier post these things are amenable to high school algebraic determination.

The power density falls off as the square of the distance according to

Pd = PtG/4 pi r^2,

where Pd is power density (W/m^2), Pt is transmit power (Watts), G is antenna gain, and r is distance (meters).

In your citation, the 100,000 Watts includes the effect of the antenna gain, it is the effective radiated power (ERP). So let's calculate the power you could receive at 1 km from the station, and compare that to the power you get from the electric grid.

The amount of power you can collect from a field with power density Pd is

Pr = Pd * G* (wavelength)^2/4 pi

where Pr is received power (Watts), and the rest were defined previously or are self-evident.

So the whole equation relating receive power to transmit power is

Pr = Pt * G1 * G2 * (wavelength)^2/(4 pi r)^2,

where G1 is the transmit antenna gain, and G2 is the receive antenna gain.

As noted above, we have the quantity (Pt G1) defined as 100 kW. A high gain receive antenna in the FM band would be a Yagi-Uda array, say about a gain of 10. 100 MHz is in the middle of the FM band, the wavelength is 3 meters. If we plug in all our values, our receive power is about 50 mW.

Your home is wired for either 100 or 200 Amps at 240 Volts, depending on where you live in the USA. I am sure it is similar in Europe.

The eternal optimist in me hopes this elementary calculation puts this ridiculous thread to rest. The pessimist in me recalls Asimov quoting Schiller...

A properly tuned transmitter areal forms standing waves. The same tube will barley glow at a distance of 200 m. (I did test it)

This low energy lights glow with enough light to see the time on my watch when I touch it in the night. (I have an old style clockwork clock). That may be because of the transformer for the alarm just next to the bed. (maybe I should wear a foil hat)

That works because the fluorescent lamp is excited by an electric field gradient, a high potential difference from end-to-end. And that is exactly what you were getting very close to that AM antenna, because it transmits a very high intensity electric field in close to the antenna element.

Note your instructor did not hold up an incandescent bulb to get this effect. The incandescent bulb relies on current flowing through the filament to heat it, and that requires energy transfer, and you aren't getting that from the nearby antenna.

The phenomenon you saw was not free space energy transfer. The impedance of a wave in free space is 377 Ohms and you have to be around a half-wavelength away from the AM antenna for that. We're looking at a football field away, and I expect the lamp wouldn't light out there. That was quasi-static field coupling - the same type of field you see around a bar magnet using iron filings. Free space coupling is when those field lines have broken away from the antenna and are traveling through space. Half the energy in the wave is in the electric field, and half in the magnetic field, and it transfers back and forth as the wave propagates through space. Very close to the antenna, all the energy was in the electric field and it was very intense, hence the effect you witnessed.

A company (SEW) build and presented a series product for manufacturing automation : transporters with a wireless supply. conditions very low distance between emitter and receiver. Usage on factory floor. power limited at about 1kW. Supply of different motors on the carriage. I personally saw it working on a fair display (real not video). Power is limited and floor has to be prepared, emitter in the floor is used as well as guide.

My humble opinion is that it is not feasible/possible/economical/efficient (chose the adjective you like)

The reason being - energy do not travel in a straight line (or a curved line ) without a guide.

Whenever no guide is there, the energy will spread in form of a cone.

We transmit the motion (mech energy) with a shaft - consider the stress distribution - on corners

Look at the pressure transmitted on flange face from bolt head (pressure cones)

Look at a humble thing like bulb

Look at the microwave transmitters/ radars

Even the lasers ( may be the most coherent source of energy) spreads out even when no scattering is there in a cone (may be angle is low but it is there)

To gather the energy at the reciever, it has to be high efficiency transducer along with sufficient diameter reciever to gather all the energy.

However if you really want to do away with the transmission lines (this portion is off topic)

a) Use local solar / wind / other NCES

b) Use home DG set (the energy - diesel/gas is not through transmission lines, through tankers, pipelines etc but not through transmission lines.

a few others may be there but like all other discussed these are equally inefficient. Yes including the solar (how much of the % of solar radiation radiated from the sun we are harnessing through our tine solar cells ? even if the total earth is covered with them ? )

If you really want to transmit energy without transmission lines, only one person cal help you : George Lucas. Contact him @starwars.com

can we close this type of topics ?

I saw something about Apple and Intel having some success at lighting a light bulb with wireless electricity. Try doing a google search on "apple wireless electricity" you may find some info on it. I believe they showed it at a trade show.

You don't read the other postings before you make a comment, do you?

Look at the links at posting #5 (MIT and...article)!

Check out the separation distance from transmitter to receiver. My wife has a rechargeable toothbrush that sits in a cradle and is recharged by inductively coupled 60 Hz power. Hardly new technology, and hardly wireless power transmission, except in the literal meaning of the words. Not a replacement for the present electrical grid.

Also, thanks to Bricktop for the kind words and GA. Engineering is indeed a high calling, as evidenced by the following exchange between Dilbert and his pointy-haired boss (from quite fallible memory):

Dilbert: Did you run this idea past engineering?

Boss: I discussed it with marketing. Marketing and engineering are the same thing.

Dilbert: If marketing and engineering were the same thing, we'd still all be sitting around in caves debating whether rocks were good to eat.

And finally, Ethobil's latest post (#24):

"What if new methods of creation and control of electromagnetic energy are discovered and what if these discoveries lead to a possible realisation of that prediction. (these are all possibilities not faith based though )"

It is totally faith-based if neither you nor anyone else has a clue of how to do this. It isn't an extrapolation, it is just a wish, a desire, an active imagination, but it isn't science or engineering unless you can make a credible extrapolation from an existing capability or understanding to your prediction.

What Ethobil said is no different than me predicting that one day a faster-than-light space drive will be invented. I can say that, I can believe it, I can hope for it, but until I can show that Einstein and General Relativity is wrong, or not somehow universally applicable, I am simply expressing a totally unqualified opinion, which is something any of the six billion people on the planet are equally capable of doing. And debating unqualified opinions is a pastime best left to politicians, who are paid well to do so.

So when JFK said

"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth."

It was just wishful thinking?

It hadn't been done, so it couldn't have been a credible extrapolation of the US knowledge base. All they knew is that the Russians had launched Sputnik.

Your thinking is sound, but only within a certain context.

There are several incorrect premises in the Guest post:

When that speech was given, the first American, Alan B. Shepard, had just achieved a sub-orbital flight. John Glenn's first orbital flight was less than a year away, and we had launched our own satellites, as far back as 1958.

The JFK speech was given in 1961. JFK was a politician, not a rocket scientist. Wernher von Braun sold him on the feasibility, and JFK believed in it. Given that von Braun had rained V1 and V2 missiles on London from Europe, and that we and the Russians had indeed launched orbiting satellites, and cosmonauts and astronauts into orbit, it is clear that sending a rocket to the moon was an extrapolation from then present technology. It didn't matter that the Russians were ahead of us, or had some technology we didn't; unless the Russians were just a lot smarter than we were, we could do it, too. And as it turned out, we were smarter than the Russians; or more accurately, our German rocket scientsts were smarter than theirs.

Guest makes it sound as if JFK's proposal was as if some alchemist in the 1300s had sold his king on the philosopher's stone: in fact, the only issues were time and money.

I was going to let this thread go until I saw the last ethobil post got a GA vote, which means someone else agrees with him, which is not a good thing. Ethobil expressed a desire and hope for and a prediction of wireless power transmission without the slightest clue as to the physics involved. That's fine, but to equate that with the work of giants who labored to understand fundamental physics so that they could put the laws of nature to good use in the service of improving mankind's lot is at best unwarranted, and at worst uninformed arrogance.

Please note I don't make this statement likely - I provided the fundamental physics of wireless transmission proving the impracticality, and this was cavalierly dismissed with an opinion that other physics might be discovered. While one cannot conclusively dispute undiscovered phenomenon, an assertion not based on anything other than a wish is an invalid argument, and it is no motivation at all until someone has some understanding of how to solve the problem.

I myself would like to add another fifty healthy years to my life, but the odds are quite against that and I can wish and hope and make predictions but none of that changes in the slightest what the cold hard truth of the actuarial tables predict. Unless I or someone else become educated in the field of medicine, and make a breakthrough discovery in how to turn back the biological effects of the passage of time, nothing changes.

I strongly urge the person who voted ethobil a good answer to read the entire thread, or at least the posts between myself and ethobil, to get the whole story. We live in an age of ever increasing scientific illiteracy, and it is disheartening to find it creeping into an engineering forum. At least within this forum, the scientific method should be enthusiastically promoted and strongly defended against attacks.

I would be the first to agree that my delivery could use some polishing. No argument there. However this comment is without merit:

"From where I sit as a pretty much 'uneducated' member of this forum it seems as though there are nearly as many levels of understanding of the sort of physics being discussed here as there are subscribers."

There is a not so subtle implication in this statement that everyone is entitled to his/her own opinion, and all opinions are created equally.

That may be true in matters of taste, but it isn't true in discussing science. In science there are things that are demonstrably true, and demonstrably false. In the middle are unproven theories that have adherents and detractors. But any scientific theory, true, false, or under construction, is a model of objective reality that to greater or lesser degree mirrors the observations we make of how some facet of nature works. The success of the theory lies in how well it explains nature, and whether or not you can make predictions from your theory about how nature works and then go find empirical evidence that the prediction is true.

Within this thread I have presented the physics and math of wireless transmission, and demonstrated why wireless transmission of energy at a distance is impractical. Not a single other post has either taken issue with the math or physics, or presented an alternative, except as an uninformed opinion that an alternative might exist.

No one can argue with that last, but it is a useless sentiment for that very reason. As I stated before, it is no more useful having that discussion than the medieval debates about how many angels could dance on the head of a pin.

I accept you don't like my writing style; I accept I could soft pedal the message and sweet talk readers into accepting my point-of-view by flattering and coddling fragile egos. Obviously, I don't take the time to do that, and for good reason: this is an engineering forum. I cannot tell whether the posters are engineers or basket weavers. If I knew that ethobil and Shadetree were not engineers at all, I wouldn't have even bothered posting these responses; I am an engineer and my posts are aimed at engineers.

Well emc c,

"If I knew that ethobil and Shadetree were not engineers at all, I wouldn't have even bothered posting these responses; ..."

Ethobil is an Engineer as well.

Yes, i do not have an evidence yet to prove that wireless transmission of power is posible. I am not oblivious about the impracticality of the concept at the moment but with the idea of the concept, it is posible to venture into the research.

Do we kill and idea because scientific theory does not support it? of course not.

That is why we have research and development.

The reasearch will defintely involve looking at existing concepts and laws governing them.

Someone has to pay for research and development. In order to convince them to pay for it, there has to be some case to be made for success. In over forty posts no one has made a case for it, other than, "Wouldn't it be nice."

I'm not killing anything. You and anyone else are welcome to investigate any venue you please, as long as you're not dipping into my pocket to do so.

i want just remove transmittion lines and put transmitters & receiver sets. remember , 50 years ago when mobile is just a joking for everyone , now a day it becomes a necessity for all. i want some this type of innovation in the field of electricity. i want some to reduce and make to nill the expendicture of power companies especially 1 putting set up transformers 2 set up transmittion lines & underground cables 3 to minimize poewr theft , which is a burning issue in India.

Mobile phones pick up signals at picowatt levels, from towers that transmit around ten Watts. How do you translate that power loss into an efficient electrical power grid?

You have mobile phone cell towers every few miles. They cost somewhere in the neighborhood of USD one million to build. You can't simply do away with the electrical grid at no cost. Each cell tower transmits an omnidirectional signal to anyone in its sector. How do you transmit thousands of Watts to each home in a sector? Assuming you could, calculate the total ERP and imagine the effect on anything trying to cross the electromagnetic field.

If you're worried about theft, how would you keep someone from simply erecting a receive antenna in his home to steal power? Unless you envision microwave or laser transmission to get from transmit station to each home, anyone can pick up the transmitted energy.

Each tower will have to have a direct line-of-sight to each home in its sector. If the beam is tight enough to aim at one home and not another over a mile separation, the frequency is high enough you will need to worry about atmospheric absorption, especially in bad weather.

These objections are just off the top of my head. People don't seem to like my posts on this subject, but you will note that no one has come up with an even remotely viable implementation suggestion for a wireless electrical grid. That should tell you something...

"If you're worried about theft, how would you keep someone from simply erecting a receive antenna in his home to steal power? Unless you envision microwave or laser transmission to get from transmit station to each home, anyone can pick up the transmitted energy." I AGREE WITH YOU. but again i want to ask you that have you hear about D.T.H DISK(direct to home disk) ? D.T.H.disk is widely used inplace of 'cable T.V.'(programs are transmitted through air wia radio frequency guided waves, catches in that disk and than goes to the SET UP BOX of the disk companey and than comes to the inout of our T.V.). none can access the programs without paying to the companey and recharging the prepaid card of the SET UP BOX of the company, STILL HAVING THE COMPLETE CONNECTION of the set up box and the T.V. and the DISK. could we use the same type of the mechanism hear?

Conceptually the power company could provide a cipher lock type affair through which power would have to pass, and without the paid-for deciphering, the power would not be delivered. But it would be easy to defeat, and with this much at stake, violations would be rife. With the movie, the encryption or other protection is difficult to defeat, because you don't know what the end product is supposed to be. And demand for black market solutions is limited because movies are a luxury. But with power you know that you want 50 or 60 cycles ac at 120/220 Volts depending on where you live, and the incoming power is a known quantity as well, so the black market manufacturer has a very easy job to do. And practically everyone wants cheap power, so the probability of mischief is approaching unity here.

rules of physics are made by us, the mankind, not nature or god. i want to convey that rules can be change; by us or by anyone innoveter. PLEASE TELL ME THAT why do we have to produce electromagnetic field by GIVING ENERGY to inductive coils? (in transformers especially). WHY it destroies after removing that voltage source? WHY the magnetic field of earth remains constant?(dosen`t destroies without applying any voltage or current source to the earth). why the flux lines of it spreads among all over the earth? could we not able to transmit power by that flux? that flux is strong enough and does not effect to any living body directly.

In turn:

"rules of physics are made by us, the mankind, not nature or god." Wrong. The rules of physics are laws of nature. They are discovered by man. We are not gods - we don't make the world. We have to learn how the world in which we live works. Again, the four hundred year old quote from Sir Francis Bacon: "Nature, in order to be commanded, must be obeyed."

"i want to convey that rules can be change; by us or by anyone innoveter." Wrong. An inventor or innovator must work within the bounds of the laws of nature. Technologies change, but they never violate the laws of nature. Read the Bacon quote, again, above.

"PLEASE TELL ME THAT why do we have to produce electromagnetic field by GIVING ENERGY to inductive coils? (in transformers especially). WHY it destroies after removing that voltage source?" Not sure what you are asking here. At the most fundamental level, energy is neither created or destroyed, so whether energy is electrical in nature or not, the energy supplied to a load must come from a source. If you remove the source, no energy can be supplied to the load. That may be an unsatisfactory answer, but it is the best I can do without further explanation of what you meant.

"WHY the magnetic field of earth remains constant?(dosen`t destroies without applying any voltage or current source to the earth). why the flux lines of it spreads among all over the earth? could we not able to transmit power by that flux?" The magnetic field of the earth is dc - it is unchanging. It is similar to the field of a bar magnet. No energy is required to sustain the field and therefore no energy can be extracted from it. You could rotate a small coil so that the magnetic field lines alternately cut the plane of the loop and then don't, thereby creating an ac potential at the loop terminals in accordance with Faraday's Law (a fundamental law of nature enshrined in one of the four Maxwell equations describing all of classical electromagnetism), but the amount of energy you get from those terminals will not exceed the energy expended in turning the loop.

"PLEASE TELL ME THAT why do we have to produce electromagnetic field by GIVING ENERGY to inductive coils? (in transformers especially). WHY it destroies after removing that voltage source?" MEANS what happnes when source of H.V.applied to one side of transformer ; another side is kept open circuited, remains some time in that position and then source removed ; what about the generated flux in primary coil ? where it goes after removing source?

To a first approximation, if the transformer secondary is open-circuited, no energy is drawn from the primary side-connected HV source.

In the general case of a load connected to the secondary side, the load impedance is reflected across the transformer and multiplied by the square of the transformer turns ratio. For instance, if the load is 100 Ohms, and the turns ratio is 2:1 primary to secondary, then the HV source on the primary side sees a load of 400 Ohms.

The flux in the iron core is generated by the current in the windings wrapped around it. If you remove the source of the current, the flux vanishes. Of course in your specific case of an open-circuited secondary, no current was flowing in the primary windings anyway, so there was no flux in the first place.

Just let me modify your speech (since we are still at it despite my #20) -

What we mean here is as the current passes throu a coil a flux is created (and not by mankind it is THE LAW OF NATURE) which we have understood and tried to harness.

The flux is created and keeps on spreading in the universe(if you like) slowly attenuating as it goes further and further away from source (inverse square law)

When we remove the input current - the flux or the EM energy is not destryed - it is still spreading over.

Asn example may make it clear- in astronomy the exploding stars are may be a few thousand or a million light year away - The same (EM Energy) we see after say 1000 Yr after the star is actually destroyed (not actually, but as a star - it might have gone to dust) - Now if the energy is destroyed as Mr/Ms makwana said we would have never observed it, but here despite the IN switch (the star) offed the EM radiation kept travelling (and of course attenuating).

Not to have the attenuation (to have an efficient transmission of energy) - you need wave guides (transmission copper is one) - or you need some other form of energy that does not need wave guides.

So question here is not how to transmit electrical (or EM) power - but to fine a type of energy that does not need wave guide as it is directed from source to sink. Currently known types need them - whether it is mechanical (sound) or electromagnetic (light, electricity, x-ray, gamma ray, Infra red, radio, ...)

There was a write up about this in 2007 or 2008. The guys at MIT lighting up a bulb with wireless electrity. Claiming they coined the phrase WY-tricity or something. I myself filed a provisional patent for the company I work for back in early 2007 for a specific application that uses the technology. (don't knwo what came of it if anything).

Anyway, the trick is resonance. You have to match the sending and recieving coils and use an ac signal that is frequency matched to the normal frequency of the coils / or a harmonic of that frequency.

As stated by others here, distance and effeciency is in question. We haven't tested it at large distances.

The picture on the web site shows the two coils a couple meters apart, at best. Consider that the induction field from an electrically short coil falls off as the cube of the distance.

The ability to transmit small amounts of power short distances has some implications for reducing wiring clutter within the home, but it is not a replacement for power transmission between generating plant and consumers.

Agreed. The app we were using it for was 2 - 6 ft. Very effective for that distance.

If I remember correctly, Tesla's ideas about transmitting power across the globe used the earth as a conductor rather than the atmosphere. I thought the tesla coil was an early test.

After going back and reading a couple of other posts, I have to apologize for reposting the bit about the MIT artcile or even posting at all. I originally read the first few posts, scanned down and saw "mind over matter" and "oh no not again"; my eyes glazed over and I replied. It appears, the question has been answered.

http://www.overunity.com/index.php?topic=2313.0;wap2

Ask TESLA...oh...he's dead...Ask those that took his research.