Another suggestion would be to use evanescent coupling with efficiency tweaks in the material and shape of the coils. There are certain conditions that really extend the "inverse square law"'s applicable distance much greater than it would due to conditions like resonance and wavelength/size of transmitter/maximum Q designs and maybe add a little bit of RF radiation to help out in the transfer of power. This topic needs a lot more research, but for house-like distances the inverse square law shouldn't be much of a problem and workarounds can be done in my opinion.

What frequency was used in the MIT experiement? Nothing like generating 150W to light a 60 W light bulb.

Evanescent coupling , nice choice of words. Evanescent meaning tending to vanish like vapor. Cash is evanescent in this project as far as I see right now.

As far as working around the inverse-square law, all I can say is good luck.

 

What is this FIOS thing anyway, a new provider? We don't know about this stuff because I'm in Canada, so is it some new internet, TV, and phone provider?

FIber Optic System. Lightwave, capable of some really fast speeds. Starts are 100MB, and goes up. Right now I'm getting my TV, landline phone, and internet and paying around $150 for the privileged. It supposed to to be $99/mo but somehow you always end up being screwed by these companies. The local cable provider is worse for an equivalent bundle.

There is no inside a transformer, inverse square rules, always. A lot like the cable or phone company marketing. Wireless is a good dream, but if it were easy it would exist. I've said this before, I've also said the only way you can get around the worst of inverse square is directional signals, but it is still there. BTW, what is to keep your neighbor from tapping into it? You will be paying their electric bills to some extent. You are still buying this electricity, and paying for the losses too. Compared to batteries this is a bargain, but cords will always be cheaper.

 

Thirty+ years ago, this may have been a good idea. But now, not so much.
Even with 80 to 90% efficiency, you will have a HARD time trying to convince consumers to WASTE or PAY an additional 20% for power then they are currently paying. Also, the big stinking power plants will have to produce 10 to 20% more power to satisfy customer needs.

As you said about line losses, to provide a customer with 220 amps of power rather than the 200 now, the transmission lines will need to be upgraded.

Who pays for this? The customer.

The amount of copper required on the device to BE recharged and the transmission units will be FAR more than in a wire to pass the power.

Then you will have the conspiracy theorists who will be saying the government is using mind control signals adapted in the wireless power signals to keep a docile nation.

 

BTW, what is to keep your neighbor from tapping into it?

Wattsnarfing - I love it!

 

Hmm ... you guys are correct I guess. There are many issues with wireless electricity.

-Neighbors can tap in
-Efficiency / inverse square law
-Receivers needing to be built in to all portable devices
-Changes to infrastructure

Oh well, we shall wait for another Tesla to shock us with a way to do this by solving the above problems like he did 100 years ago. For now, I think I'm going to abandon the project to any further point, but I still am going to build a small scale model for amusement. *sigh*, don't you just hate it when you worked on something for 2 years to just abandon it ... I guess it's normal in engineering.

Thank you guys for being patient with my nagging questions and persistence on this subject. Special thanks to Bill Marsden.

 

Don't give up, but know the limitations. Solid state devices such as lasers are getting more efficient all the time (and are the ultimate in directional). Same with solar cells.

Speaking of solar cells, their efficiencies are going to be taking some nice jumps in the near future, and they are even better than wireless. Keep up on the literature. One of my favorite sites is http://www.physorg.com/

 

Thank you Bill. This wireless thing will always be in the back of my mind. Just these limitations brought my hope down a bit and they're not easy limitations: we're talking about major efficiency and infrastructure issues.

I will keep my dream the way it is, but use a different method like you mentioned. I will read into solar cells and lasers. Thank you once again Bill. Very much appreciated.

 

Don't give up. They are called laws for a reason. Work on any hypothesis you wish. There may be a zero coke theorum in the future. The one thing you will have a tough time doing, is breaking a law ... like the inverse-square law.

 

I think you should break the problem down.

First, find the most efficient way to get high speed, low power switching for the magnetic field.

That will be a major point in what you need done.

Dont abandon your dream. Just expand on it.

First get wireless power on your desk. Then re-evaluate.

 

Hmm ... you guys are correct I guess. There are many issues with wireless electricity.

-Neighbors can tap in
-Efficiency / inverse square law
-Receivers needing to be built in to all portable devices
-Changes to infrastructure

Oh well, we shall wait for another Tesla to shock us with a way to do this by solving the above problems like he did 100 years ago. For now, I think I'm going to abandon the project to any further point, but I still am going to build a small scale model for amusement. *sigh*, don't you just hate it when you worked on something for 2 years to just abandon it ... I guess it's normal in engineering.

Thank you guys for being patient with my nagging questions and persistence on this subject. Special thanks to Bill Marsden.

Don't give up your dream for low power wireless. Others have tried and had some success.
http://contentdm.lib.byu.edu/ETD/image/etd1455.pdf

 

You guys are awesome! Thank's for the encouragement and continued support! This forum rocks!

 

Inverse square law is for propagating RF power density. It's also for field strength of certain things.

A magnetic or electric field that isn't propagating isn't using power except in the losses of generating it (and before this starts, I said 10 times over that the propagating component is orders of magnitude smaller unless you have a good radiator).
Field coupling like this doesn't follow the inverse square law - you will have an inverse cube law for field strength but the energy isn't being sent in every direction.
It is exactly what a transformer does...

Evanescent refers to non-propagating when you're talking about waves.

 

Yeah I read about the inverse cube law with regards to magnetic field strength too. Here is an excerpt from the article:

Research is continually being conducted on solutions to reduce the size of antennas
and coils without compromising their performance. The coupling distance between
the transmitter and the receiver of circular coils are limited by the near-field magnetic
field strength (H) of the devices that decreases as the cube of the distance between the
two (R^3) increases. Based on the desired maximum distance that one would like to
receive power, the magnetic field strength would have to be large enough to
accommodate that distance.

-Gerald R. DeJean, Ph.D
Microsoft Research
September 27, 2007

 

How do you get through the medium of air if the magnetic wave doesn't propagate?

Since we are talking antenna's ... two fields get propagated, on H and E. H is the magnetic field. There were studies twenty years ago using the H-field when using Loran C (a 3000 meter wavelenght), as it is more resistant to p-static. Reception of those signals were hundreds of miles.

Evenescent is an adjective referring to the quick dissapation of the wave.

 

Magnetic and electric field act at a distance.
Just like in a transformer - it's not through the wires, so what's it going through?

 

How do you get through the medium of air if the magnetic wave doesn't propagate?

If I'm not wrong a magnetic field doesn't require a medium. The earth's magnetic field extends out to space and there is a vacuum in space, so no medium. Or is there? Dun dun dun...*ether*

And regarding the evanescent coupling, I think evanescent or quickly vanishing fields is required in this project for some reason. I think quick collapse and re-building of the magnetic field somehow increases the distance or efficiency. I'm not too sure what it's all about, but all I know is it helps a lot in efficient power transfer. I'm reading the publication by M.I.T but I don't quite get it because I'm only a 1st year electrical engineer. Their terminology and equations are hard to understand for me.

 

The medium is the space the wave travels through. It could be air, metal, space, water, humans, glacial ice ... et al.

Each presents a different problem to the transmitted wave and could be detrimental. It may not affect your project at 60 Hz ...

Gar ... it's going through whatever is between the source and the reception point.

Wireless infers you are going from point A to point B .... without wires and through the AIR.

 

How do you get through the medium of air if the magnetic wave doesn't propagate?

Since we are talking antenna's ... two fields get propagated, on H and E. H is the magnetic field. There were studies twenty years ago using the H-field when using Loran C (a 3000 meter wavelenght), as it is more resistant to p-static. Reception of those signals were hundreds of miles.

Evenescent is an adjective referring to the quick dissapation of the wave.

"Quick dissipation" in the context of propagation.
I believe an inverse cube law qualifies... like zero_coke's quote says, you just need to have the field strong enough to still do something.

I don't know much about Loran in particular but it definitely sounds like an RF propagating system with huge antennas. Once it's propagating you can receive either E or H or both.

The whole point of this field coupling is to avoid having a good radiator. If you do that the propagating component will be insignificant compared to the near field components. The near field strength follows inverse cube but it is not propagating energy so it does not have the huge efficiency hit that RF does.
You're severely limited in distance because of the cube law but it can be very efficient as seen in transformers. At further distances your field has to be very strong to be useful so the efficiency naturally goes down but that loss occurs in the generator and whatever conductors pick up the field, not the air itself.

 

When you read Shipley's Master Theses, the link that nsaspook posted, Shipley reported there were any directional antenna's for the CB/Amateur(ham)/Marine radios. There may not be any commercially available ones, but you can certainly build them.

You can make a wireless router have directional antennas.

 

The near field strength follows inverse cube but it is not propagating energy so it does not have the huge efficiency hit that RF does.

Your not propagating electromagnetic energy?

Any wave that disapates by the inverse-cube law will be more inefficient.

Shipley's Thesis was for 30 feet.