Scavenging ambient electromagnetic energy


At this very moment, unseen radio waves are bouncing off almost everything that surrounds you. Emitted by everything from radio and TV stations to cell phone networks and satellites, these waves are full of unharnessed energy. That is, until now. Researchers at the Georgia Tech School of Electrical and Computer Engineering have been working diligently to harness this unused energy, and recently unveiled their new antenna technology at the IEEE Antennas and Propagation Symposium.

The team, led by professor [Manos Tentzeris] has been working to develop ultra-wideband antennas to tap into the energy all around us. Using printers filled with a specially-formulated ink compound, they have been able to print these antennas on paper and polymer substrates. The antennas can harness energy stored in radio frequencies ranging from 100 MHz all the way up to 60 GHz, depending on the printing medium.

The team can currently power temperature sensors using television signals, and is preparing a demo in which they will power a microcontroller simply by holding it up in the air. The technology is still in its infancy, but the list of applications is almost endless. We doubt you’ll be powering your TV with this technology any time soon, but it definitely holds promise for things such as wireless sensor mesh networks and the like.

[Thanks, morganism]

65 thoughts on “Scavenging ambient electromagnetic energy

  1. This is nothing new. If you have a building close to the transmitter station, with several well positioned antennas, you can heat up your house with the energy you harness, from the propagating waves.

    As it is widely known, enerygy does not get destroyed. It just changes form. So, take radio signals with a certain energy and convert it to heat, effectively attenuating the power of the signal for the people in the distant reception points. So, it is only miliwatts and too little to be usable argument don’t hold water. You harness that energy in the form of generating some other form of energy, and you are denying reception to the fringe edges of the reception area.

  2. “To print electrical components and circuits, the Georgia Tech researchers use a standard materials inkjet printer.”

    Wait a minute. Doesn’t this mean they have also solved the problem of printing PCBs? Something that hackers have been trying to do cheaply for years without having to etch PCBs?

  3. For wide bandwidth give fractal antennas a try :)
    To ensure as little voltage is dropped across your rectifier as possible use a schottky diode. They are also quite fast diodes, so they should let you operate at fairly high frequencies.

    What I would like to determine is whether more power can be harvested with a wideband circuit (as I’ve described) or with a high Q tuned circuit. It likely depends where you are I suppose.

    But anywho that’s my 2 cents.

  4. I was going to make a comment about the university being in Georgia, but I see a University in my home Sate of Kansas in getting in on the act as well. KSU energy harvesting radio, A dream of backyard engineers for just about forever now. “Coming soon” can be read at a web page referenced by another. Photovoltaics, and batteries are mature, improving technologies that can do the jobs these device promise to do,and more. I know many want to believe this will effect the services that others use, but they really understand how much man, and nature made items out there that exist that affect RF now with little effect in general?

  5. After having a moment or two to briefly scan the PDF file about the KSU project, at this time it’s “energy harvesting is limited to solar cells, no RF energy capture. While stating battery free operation is a goal, but this project, doesn’t seem to address how to accomplish that. IMO RF energy capture might have to charge a battery to have enough power for transmission of data bursts to support a mesh network. Enough bench racing for today.

  6. It’s good that this research has such noble aims, in terms of it’s ease of implementation; simply printing off your own voltage source. There’s no doubt in my mind that they’d be able to power an MCU from one of these devices, but I feel that there’s not really any real world application for it. A lot of buildings have structures that are similar to Faraday Cages which would render a device like this pretty useless.

    But, what makes this so awesome is that they can print of antennas capable of radio! This is what I just don’t understand because usually for circuit patterns like that the underlying PCB structure is critical, requiring very specific layers. I hope they publish exactly how they’ve gone about doing this.

  7. I disagree with many of the posts on here saying that capturing this energy will hurt your TV (wifi, etc) signal.

    Television is mostly line of sight. All of the other energy emitted by the TV towers get bounced around and eventually absorbed by everything else in the world. So if you absorb some of the energy, you’re just taking away what would have been absorbed by the rocks, earth, buildings anyway.

    No one is hurt by this process, though I doubt that there’s very much total power in it. Solar probably has a lot bigger return on investment.

  8. On chip antenna could work, this has been done with RFID chips in the 13.56 MHz band.

    You can now buy miniature ceramic antennas tuned to:- GPS, Bluetooth/WiFi, etc.
    So an array of these with each one tuned to a different frequency would make a compact assembly indeed.

    I came up with a variant of this just now which uses a blue LED tuning diode to set the resonant frequency of a tuned circuit so that it covers the entire medium and longwave band from 60 kHz to over 2500 kHz with one ferrite rod antenna.
    Might work, at least to flash an LED or two.

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