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Radio Energy Harvested With Inkjet-Printed Antenna
judgecorp writes "Everlasting green energy for RF tags and other low-power devices could be possible as scientists have harvested energy from ambient radio waves using cheap antennas printed by an ordinary inkjet. The scientists, from Georgia Tech, started at 100MHz but have now produced systems which scavenge power at up to 60GHz, allowing them to draw power from most of today's major radio technologies."
Because it seems like if you want to power these things, they need to use power from a radio source. Which doesn't make them green at all.
It's called a crystal radio.
A diode does it too.
http://lkml.org/lkml/2005/8/20/95
There are many cool projects out there where you can 'harvest' free wireless energy. I've read about people setting up receivers to pull energy (low wattage of course) from nearby microwave towers and the like. Don't have any sources, but I believe I've heard of some research teams or 'how to get free cheap power' sites/groups being harassed by the folks who owned the towers. All heresy, could not find any sources, anyone know anything else?
Also, and sorry for the cliche attribution, Tesla was a major proponent and researcher in this area, and wasn't a complete kook as revisionist history sometimes paints him to be. Margaret Cheney's "Tesla - A Man Out of Time" is a great read for a comprehensive history covering some of the early research in these areas.
'We are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.' RPF
Comment removed based on user account deletion
Yep. TANSTAAFL
I am not a radio scientist, but ... if the new tech pulls power out of the radio signal, isn't this going to a) degrade the signal for anyone 'downstream' of the absorber, and/or force broadcasters to pump MORE power out to maintain signal generally?
-Styopa
Maybe a dumb question, but do RF sinks like this act like 'black holes' for radio waves, affecting the reception quality within a kind-of 'event horizon' vicinity (maybe even requiring more power at the transmitter) ?
I don't think you can measure the effect at the transmitter of generating a wave that was otherwise destined to be absorbed by the surroundings or dissipated into space vs being detected on an antenna.
Perhaps a log floating on a pond into which you throw a rock blocks the ripple and creates a lee, and perhaps a lillypad in that lee bobs less, bit it makes no difference to the stone you throw unless your primary aim was to ripple that particular lillypad.
I suppose you could totally mask the intended receiver (TV aerial) of that TV signal by wrapping it in these paper antennas.
But the energy was already expended sending the wave. The transmitter won't need more power if that signal gets absorbed by the buildings or by the paper antenna. The antenna can only capture the energy already impinging upon it from the signal. It can't pull any more from the transmitter.
Sig Battery depleted. Reverting to safe mode.
I wonder what the nominal ambient flux actually is (i.e., W/m^3), and how much of it they're actually capturing.
110100 1101000 1101000 1100110 0 1101111 1101000 1100011 1
Which reduces the quality of the radio signal for anyone downwave from the power harvesting site. It effectively steals power from the transmitter intended to provide service to those more distant than you from the transmitter.
Permissible is interception for purpose of reception of the signal, such as a crystal radio, at a small scale. Not permissible is powering your lights, robots, or anything else that does not simply turn the signal back into its intended form.
It may be permissible to leech power from a WiFi signal in order to power a device that will use the data in the stream if you could be sure you're stealing power from signals intended for you and no one else.
But AFAIK the rules are to protect man-made signals, unless the scientific community have petitioned to protect their ability to study background radiation by preventing the same harvesting of power from natural radio sources, else they'll have to do their studies elsewhere.
Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
I'll give you a little dirt on solar panels too - they cast shadows, robbing whatever is in their shadow of its rightful electromagnetic energy! Same thing, different part of the spectrum.
Joke all you want. But a group in one of my engineering classes did this and we were received better than the group that did: .00something watts.
I guess marketing is easy.
I don't think you appreciate how minute the amount of energy you can recover from radio waves is. I doubt you could recover enough energy to cover the power used by devices when "off".
Maybe a dumb question, but do RF sinks like this act like 'black holes' for radio waves, affecting the reception quality within a kind-of 'event horizon' vicinity (maybe even requiring more power at the transmitter) ?
Not Really.
EM comes in two main flavours
Near Field & Far Field.
In the near field you have a good chance of 'loading' the antenna, thus 'robbing' power but you need to be mighty close at high frequencies. eg. Within few cm at 1GHz.
In the far field, the EM wave propogates, and you as the reciever have no influence on the transmitter.
Do you rob other recievers around you? Yes, but the effect when compared to buildings, trees, the earth would negliable. A propogating wave will also fresnel around you. You would be like a speck dust to sunlight.
46137
You'd have to show that the photons couple, so that energy sapped from the radtion in one angle will affect the energy present along another angle.
Good luck.
-josh
Why do so many of recent "technology breakthrough" articles follow the same pattern.
1. Take an experiment that shows some minor interesting results (in this case the ability to pull microwatts from radio waves)
2. Extrapolate it into unproven areas (in this case the ability to pull a milliwatt)
3. Combine it with another theoretical, non commercial technology like superconducting motors, lithium air batteries or in this case super-capacitors.
4. call it a breakthrough
In my mind it is not a breakthrough until the technology is scaleable and commercially viable. Until then it is interesting science and only that.
I think you mean that marketing has polluted the word so thoroughly that it is hard to take it seriously. In a way it has been gang raped and never truly recovered.
However, the intended meaning of "green" to scientists and intellectuals (I guess) is that the technology results in a net loss of expended energy somewhere. It may be generating energy, or just being more efficient at an unclean process, therefore making it "green" because it is not as bad as the alternative.
Calling Flex Fuel "green" when it requires so much corn to help make it that the environmental impact, resources, and energy required to produce it that it is marginally better (or not better at all depending on who you talk to) is an example of taking "green" and tarnishing it.
The Prius is definitely green because, although it still uses fossil fuels, it is generally 100% increase in fuel efficiency over existing models. That is still green.
Personally, "recycling" the energy used from radio waves is a pretty damn good idea. I would take it a step further and create a drywall product that incorporates it and pushes the power back into the house in the form of air cycling, purification, subtle lighting, etc. I don't know how much could be harvested, but there is quite a bit of radio waves hitting me even now. My wireless N, my neighbors wireless, satellite signals, FM, AM, military, garage door openers, cell phones, etc. Be pretty neat to have cheap wireless access points installed in each room, and every room absorbing the radio waves that are not used. Obviously, some rooms would not have the special drywall so they could receive wireless from an joining room.
This is absolutely green. I know it is the first time I have heard of even recycling radio wave energy.
Of course, the FCC mandates to you may not interfere with the signal, but I think it would be a dubious argument to say that you cannot prevent signals from penetrating your own house.
You completely missed my point. It's not about bragging rights, or which is more efficient.
The fact is that BOTH the Prius and the Polo Bluemotion are significantly more efficient in fossil fuel use. This leads to:
1) A decreased dependency on Oil.
2) Proof that these technologies work and that we have the opportunity to learn from them as they are in use everyday.
3) What I also did not mention, was that the Prius, also produces less pollution. I assume the Polo Bluemotion does the same?
If it accomplishes less pollution and a reduced energy consumption, then it is green by definition. Arguing that B is better than A, and therefore A should lose its status as green is just a little bit silly.
They are both green and can be marketed as such.
Marketing the Flex Fuel as green is wholly retarded and disingenuous, and the only people behind it are those that stand to profit by it.