Focused Microwaves Could Enable Wireless Power Transfer

esocid alerts us to news out of the University of Michigan, where physics researchers have found a way to focus microwaves to a point 20 times smaller than their wavelength using a new 'superlens'. Such resolution was thought to be impossible until recent years, and it could bring about the capability to transfer power wirelessly. "No matter how powerful a conventional lens, it cannot focus light down to more than about half its wavelength, the 'diffraction limit'. This limits the amount of data that can be stored on a CD, and the size of features on computer chips. The new lens is a 127-micrometer-thick plate of teflon and ceramic with a copper topping. 'The beauty of these is that they're planar,' Grbic says, 'they're easy to fabricate.' The lenses can be made through a single step of photolithography, the process used to etch computer chips."

Superlens = spillover = irradiation

[G4from128k]

What I remember from studying this technology 15 years ago was that it was possible to create a beam sharper than the diffraction limit, but the result was diffuse spill-over. That is, one could create an extremely sharp main lobe in the beam pattern, but one had to suffer higher side-lobes. That's OK for imaging and lithography applications -- the spill-over is diffuse enough not to cause too many problems. But for power applications it means both inefficiency (power lost to the side lobes) and irradiation for people who think they aren't in the beam.

Re:Superlens = spillover = irradiation

[DougBTX]

Here's what the diffraction pattern [sciencemag.org] looks like, quite impressive.

You may have forgotten...

[MichaelSmith]

The content you requested requires a AAAS member subscription [...]

Re:Misleading title

[Ungrounded Lightning]

While it's nifty that they can focus EM radiation to a smaller point now, I'm not following how this will enable wireless power transfer.

Smaller rectennas. Higher efficiencies. Less land use for the receiving end. Lower cost as a result of all three.

Less power beam soaking into other things, too, which means you can find a receiving site closer to the load and shorten the transmission line.

Re:Never mind the power thing

[NeverVotedBush]

Circuit fabrication is already using x-rays for the really fine feature devices. The lens they made was for microwaves - much much longer (orders of magnitude longer) wavelengths, where the feature size is possible to construct the capacitors.

The feature size to be able to lens visible light will be much much smaller, and to lens x-rays, will be smaller still.

Since they are using photolithography to create these devices now, they are using a much shorter wavlength of light to make features that allow the lens to work with much longer wavelengths.

To be able to create features small enough to lens x-rays, they will need techniques that don't even exist now.

There could always be some other innovation that this new technique enables, though. Maybe it could eventually happen.

Catching up with me?

[slack-fu]

I've had wireless wireless extension cords for YEARS. I can't believe you guys think this is new, here's the site i got mine from. BTW they work great! Wireless extension cords [thinkgeek.com]

Re:Nothing new here; still not a good idea

[khallow]

What I hear is that you can get 85% efficiency on a pass through Earth's atmosphere (between ground and orbit) (which is about equivalent to maybe 8-10 km of sea level atmosphere). That's pretty good and it improves as you increase in altitude. At 18,000 feet (or a bit over 5000 meters) the inefficiency is halved (to I suppose 92-93%). And I'm dubious about your claim that wire is more efficient. Sure running a microwave along the ground is crazy. But bouncing it off an orbital reflector is pretty efficient (or starting with a solar powered satellite in the first place).

Re:We tried that

[NeverVotedBush]

What I was referring to was current squared times resistance which equals power. The R was resistance and not radius. V = I * R, and W = I * V. Therefore, W = I * I * R.

Likewise, the IR drop is also just Ohm's law which equals voltage. The resistance will have some value per unit length and the longer the length, the more voltage drop.

The way to drop the current, so the I^2R (watts) losses can be reduced is to increase the voltage. But as you go to higher voltage, and higher altitude, where the air pressure starts getting low enough to support a plasma discharge, insulation starts getting important which just leads to more weight, etc.

No registration required

[dietlein]

Here's what the diffraction pattern [sciencemag.org] looks like, quite impressive.

Here is their other paper [arxiv.org] (no registration required) on the design of these near-field focusing plates. The results are quite impressive indeed; there are no sidelobes or spillover to speak of. The concept to understand here is that the final radiation pattern is designed (it's the starting point, in the math), and the required focusing plate geometry is the result of solving the equations in the paper.

Cutoff Point.

[pavon]

The energy in question is coming from the sun, and was going to enter the biosphere anyway.

Some of it would have, but some of it would also be reflected. On average, the earth has an albedo (fraction of light reflected) of about 37%.

To a certain extent, the effect will be the exact opposite of what you are thinking, as the sunlight would have most assuredly heated the land, sea and air, but beamed down to the electrical grid, it will be stored in other forms

In the long run it will all be converted to heat. Furthermore, there are very few uses of electricity that result in storage as potential energy of some form. Looking at California data [ca.gov], the Residential, Commercial, TCU and Streetlights will all be AC/lights/electronics which will be converted to heat immediately. The mining sector and industrial sectors will result in some potential (lifted mass, increased chemical potential of stable compounds, etc) But the machines they use to do this are not very efficient. Even if we are very generous and say that half of their energy is used for these purposes, and those machines are 50% efficient, that gives 5% of total energy use being converted to potential form.

So if the energy efficiency of the panel/beam is greater than about 100%-37%-5% = 58%, then this system will result in more heat than would normally occur from the sunlight.

Of course, even if it does significantly increase the amount of heat generated for the fraction of sunlight that it captures, that is still a tiny fraction of the sky that is covered, and the net result will be completely negligible compared to just about anything else.

Tesla

[StarfishOne]

The name of Nikola Tesla has been mentioned a few times already in this thread.

I just want to say: if you don't know or barely know something about this man, I really really recommend reading about him.

He's one of the greatest geniuses of the last few centuries. Called "The Father Of Physics" and "the man who invented the twentieth century".

Especially the latter is NO understatement. His list of inventions is huge and the combination of genius and being a workaholic (sleeping 3 hours per day) resulted in something over 700 patents on his name. He can even be related to over 1200 patents!

Although he is sadly barely mentioned in schoolbooks, he is the inventor of things like:

- The Inductor/AC motor
- The Tesla Coil
- The radio (a court ruled he was first, not Marconi!)
- The AND logical gate
- Wireless transfer of electricity
- Tesla turbines (bladeless turbines)
- X-ray tubes
- Robotics
- Fluorescent lamps
- VTOL aircraft!
- Polyphase systems
- Remote control; he had a remote controlled boat in 1898!

This list is NOT COMPLETE

See:
http://en.wikipedia.org/wiki/Nikola_Tesla [wikipedia.org]

And the really big bang is that it's very very likely that he managed to extract free energy from the vacuum/atmosphere.

Together with two other people, he has been riding a car for a week long... a silent car which had just an antenna system... reaching speeds in the order of 90 miles per hour.

He really was one of the most extraordinary persons to ever walk on this planet.

Sadly the problem was that, despite his genius, he was not a great business man. Money was always a problem and basically everyone (Edison, JP Morgan, etc.) tried to make money of this man who was so hard to make this a better world.

Now why is this man barely recognized for his achievements?

And why does he not have AT LEAST one Nobel Prize?!?

Interesting interview:

The Tesla Conspiracy: Mark DeMucha Part 1 of 11
http://www.youtube.com/watch?v=yzxvhA72vGI [youtube.com]