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[AE6RQ]

I'm just shaking my head on this one. Does anyone else see any technical issues with this article?

http://cleantechnica.com/2013/11/12/harvesting-lost-wave-energy-air-new-device-generating-electricity-wireless-energy-achieves-37-efficiency/

[KA0HCP]

Never heard of that, but I know about Commander Cody and His Lost Planet Airmen!

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

[G7MRV]

I'm just shaking my head on this one. Does anyone else see any technical issues with this article?

http://cleantechnica.com/2013/11/12/harvesting-lost-wave-energy-air-new-device-generating-electricity-wireless-energy-achieves-37-efficiency/

I take it you are being sarcastic?  

If not, well, where should I start?

'metamaterial'? Its a loop etched on a PCB, Ive done this myself before, I wired half a dozen crystal sets in parallel each with its own 30m longwire. This was many years ago so dont have the results any more, but from 'lost waves' ie ordinary receive level signals, yes the voltage was quite high, a few whole volts, but the actual power was miniscule.

They dont even know the difference between voltage and power in this article (or its deliberate to mislead), likewise they only say it converted 'microwaves', but dont say at what level. Yes, I could easily get 7v from that array if I stuck it next to the UHF transmit array at work (a mere 7MW), I suspect that they also had the source of the energy rather close at hand

If all these so called wireless energy transfer methods were at all usable, well, we'd have been charging our handhelds with them for about 50 years already

Im afraid I can no longer access current science journals, but im sure someone on here will be able to get at Decembers Applied Physics Letters. I'd like to see their paper, if any good it would be possible to replicate what they did and get the same results, but somehow I doubt their paper will be repeatable

[NN4RH]

Follow the link in the article to Duke University, then the link there to the APL article.

Whoever wrote the OP linked article didn't understand what they were reading in the APL article.

The actual Applied Physics Letter article is not as "sexy" as the cleantechnica.com article implies.

[K1DA]

     Can you pay for it with bitcoins? 

[KA0HCP]

No, but you can measure it with Dozy Watts!

[W4KYR]

Kind of reminds me of the classic demonstration of placing a florescent light close to the proximity of the antenna tower of an 50kw AM broadcast station and watching it light up without any means of external power.

I have heard about people experimenting with crystal radios connected in parallel years ago. I'll bet there might be some videos of it on Youtube.

[W1JKA]

I was raised on small family antenna farm, so am interested in knowing if these waves are best grown in free range space or plowed ground containing a high salt content and also any alternate fertilizer other that what has been suggested here so far. I have a few acres and thinking about growing some waves and selling the excess to back to the local power comp. to cut down on the electrical cost of running my basement grow lights.

[KE7AXC]

While the original article may have missed the mark a bit, some of the commenters appear to have expended their ammunition supply without knowing what they were shooting at or even what direction to fire!

I didn't understand all of what is in the Applied Physics Letters article, but it is real research funded by the Army to investigate materials that will convert incident RF energy to DC power.  Definitely not science fiction and looks more complex than just an antenna pattern etched on a PCB.

The article doesn't say what the end goal might be.  It does say "Metamaterials can be adapted to various applications, such as flexible sheets to cover surfaces."  and "The SRR power harvester is an example of functional metamaterial that may be suitable for a wide variety of RF applications that require power delivery to any active integrated components."  Maybe you'd put something on a uniform or a vehicle that would provide enough power for an IFF transponder or a sensor of some kind that would be powered by and respond to an RF signal.  Maybe some sort of surveillance sensor that could be deployed and not need a power source that would degrade over time.  Sounds like something the CIA or NSA might use.  Then again I didn't take the time to investigate uses further so I may be way off on that subject.

[SWMAN]

    DUUUDE !!!!

[K1DA]

    Will it stop Global Warming?

[AA6YQ]

If you don't think it's possible to "harvest" enough energy from RF to power a useful circuit, please explain how (unpowered) RFID tags work.

Here's a hint.

       73,

          Dave, AA6YQ

[KI6LZ]

Someone say Commander Cody?  https://www.youtube.com/watch?v=QDbON8udTPo

[NK7Z]

If you don't think it's possible to "harvest" enough energy from RF to power a useful circuit, please explain how (unpowered) RFID tags work.

Here's a hint.

       73,

          Dave, AA6YQ

I agree with Dave, can you say Crystal Set...  The first RF energy harvesting device ever built!

[K2GWK]

Didn't Tesla propose something like this 100 years ago.....http://www.teslasociety.com/tesla_tower.htm