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Cellphones Power

Nokia Developed Wireless Power-Harvesting Phones 246

Al writes "An engineer from Nokia's UK research labs says that the company is developing technology that can harvest ambient electromagnetic radiation to keep a cellphone going. The researcher says that his group is working towards a prototype that could harvest up to 50 milliwatts of power — enough to slowly recharge a phone that is switched off. He says current prototypes can harvest 3 to 5 milliwatts. It will require a wideband receiver capable of capturing signals from between 500 megahertz and 10 gigahertz — a range that encompasses many different radio communication signals. Other researchers have developed devices that can harvest more modest power from select frequencies. A team from Intel previously developed a compact sensor capable of drawing 6 microwatts from a 1.0-megawatt TV antenna 4.1 kilometers away."
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Nokia Developed Wireless Power-Harvesting Phones

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  • Why not solar? (Score:3, Interesting)

    by j0se_p0inter0 ( 631566 ) on Wednesday June 10, 2009 @07:09PM (#28286873)
    "Harvesting" is cool and all, but what I've been wondering is why manufacturers haven't been putting solar panels in phones. Such as my Casio G-Shock watch I bought 3 years has solar panels built into the watch face and a rechargeable battery, and works fantastic. I was looking at the iPhone the other day and thinking they could probably do the same thing with the large surface area of the "face" of the phone. Seems like a logical, relatively easy addition if you ask me.
  • by KefabiMe ( 730997 ) <> on Wednesday June 10, 2009 @07:16PM (#28286935) Journal
    Wouldn't this draw energy out of the radio signal, thus making it weaker? If this becomes popular in Los Angeles, will a radio station's not be able to broadcast as far because a million people are leeching power off it's transmitting power?
  • by heretic108 ( 454817 ) on Wednesday June 10, 2009 @07:18PM (#28286961)

    Shouldn't be too hard to harvest energy from changes of momentum and orientation, similar to how many mechanical watches have for years been able to wind themselves.

  • College experiments (Score:3, Interesting)

    by get_your_guns ( 1380583 ) on Wednesday June 10, 2009 @07:19PM (#28286973)
    When I was in college in the early 80s we built inductive loops to draw power from the local radio station. We drew enough power to light an incandescent bulb. The only problem was the radio station had remote power meters across their broadcast footprint, and we dropped their power levels significantly for the station to call the college. The funny thing was the college knew exactly what professor to call for this was done repeatedly through the semesters, and the radio station could get a pretty good reading on where the actual drop was coming from per their power readings.
  • by HTH NE1 ( 675604 ) on Wednesday June 10, 2009 @07:27PM (#28287063)

    And playing Star Wars lightsaber battles using florescent light tubes at night under high power lines.

  • Henrich Hertz (Score:5, Interesting)

    by SuperBanana ( 662181 ) on Wednesday June 10, 2009 @07:30PM (#28287081)

    Another great example as to how Tesla has shaped our future. Truly ahead of his time by leaps and bounds.

    I know Tesla is a posterboy for the Slashdot community, but I think you mean []. Hertz was responsible for the discovery that you could generate and detect radio waves.

    That lead to the use of radio for communications, which is why such a modern device as the article describes. Tesla envisioned pumping energy into the air via dedicated stations. I don't think he envisioned a situation where we would be pumping so much energy into the air for communications, that there would be usable power as a byproduct.

    I find it frightening, not "cool", that such a device is possible, given that my body relies on faint electrical signals.

  • Re:Crystal radio (Score:4, Interesting)

    by MichaelSmith ( 789609 ) on Wednesday June 10, 2009 @07:35PM (#28287127) Homepage Journal
    There was this guy I heard about who lived next door to an AM radio transmitter. The transmitter site was encircled by a cyclone wire fence which made a complete loop with the gates closed. Being an enterprising sort of chap he immediately saw the potential of this arrangement and went to work with power diodes and an inverter. Eventually he got found out because they weren't getting the range they expected and techs were sent in to find out why.

    As a very young geek I spent many a night tucked in bed listening to my crystal (actually geranium) radio. But I had a couple of metres of hookup wire for an antenna. This article talks about short wavelength stuff, but I still think you would need a lot of metal to collect a significant amount of power. MY cellphone charger supplies (I think) 300mA.
  • Re:Crystal radio (Score:3, Interesting)

    by artor3 ( 1344997 ) on Wednesday June 10, 2009 @08:18PM (#28287481)

    Not really. Cellphones, along with cars, buildings, trees, people, and nearly everything else will already weaken the signal. That's why devices can easily transmit 10 billion* times more power than would be needed by the receiver in a lossless environment. We might as well grab some of that power back out of the air and put it to good use, instead of just letting it turn to heat.

    * 10 billion == 100 dB, which is an entirely reasonable attenuation from transmitter to receiver, but the actual multiplier varies. Most devices will adjust their output power based on the strength of the signals they're receiving so as not to waste electricity.

  • Re:Crystal radio (Score:4, Interesting)

    by MichaelSmith ( 789609 ) on Wednesday June 10, 2009 @08:32PM (#28287585) Homepage Journal
    I did an amateur radio course when I was 16. At one point we did a field trip to the Radio Australia transmitting station in Shepparton. They had old transmitters on display which were just like a normal valve radio, scaled up to the size of a small room. It even had an air gapped tuning gang in the middle with a steering wheel on top. Amazing stuff.

    One of their operational transmitters had a gauge showing two kilowatts of reflected power from the antenna. We asked, but the staff wouldn't let us take it home, even though they weren't using it for anything.
  • Why not atomic? (Score:3, Interesting)

    by roc97007 ( 608802 ) on Wednesday June 10, 2009 @09:14PM (#28287955) Journal

    Why not atomic?

    What made me think of this was the digital watch I had back in the late seventies that used radioactive tritium for a backlight. It was bright enough on a dark night to use as a flashlight. The only downside was that there was no way to shut it off, a disadvantage when going out to a movie. (Oh, and my left arm fell off. Not really.)

    The significant advance since the times of Tesla is that devices take much less power to operate, which is, I think, the real reason broadcast power has become interesting again.

    During recent years, there's been significant advances in atomic batteries. So, given that, why not atomic? If a device is typically replaced every three years (or one year if from Apple), I wonder if a tritium betavoltaic (for instance) of sufficient capacity could be made small enough to reside in the device, either powering it directly or charging a conventional battery during periods of unuse.

    I'm thinking, watches, almost certainly. Solid state personal music players, possibly. Phones... maybe?

  • by Jah-Wren Ryel ( 80510 ) on Wednesday June 10, 2009 @11:31PM (#28288929)

    Shouldn't be too hard to harvest energy from changes of momentum and orientation, similar to how many mechanical watches have for years been able to wind themselves.

    Like these guys. []

  • Re:Crystal radio (Score:5, Interesting)

    by fractoid ( 1076465 ) on Thursday June 11, 2009 @12:56AM (#28289431) Homepage
    They're not "drawing" power from the antenna. They're just scooping up some of the power that's already being splashed around.
  • by infolation ( 840436 ) on Thursday June 11, 2009 @06:40AM (#28291075)
    Richard Box's 'Field' [] artwork is probably the most amazing example of this - 1301 florescent tubes arranged in a grid under electricity pylons lines...
  • by Ungrounded Lightning ( 62228 ) on Thursday June 11, 2009 @09:46PM (#28303325) Journal

    The power doesn't actually flow IN the wires. It flows in the fields AROUND the wires. It falls off pretty fast. But there's a LOT of power in a high-line so there's a non-trivial amount at ground level outside the right-of-way.

    Back in the '60s at EE school I heard a story (from the prof). Seems a farmer who had the local power company eminent-domain a right-of-way through his land to put in a high-line, but still wanted tens of thousands to run a service drop to his farm. This guy got ticked. So he strung his own line under the high-line, thus coupling to it (both inductively and capacitively) and used ordinary utility transformers to convert the tapped power to a voltage suitable to run his milking barn.

    Power company noticed the drain and tried to bill him. He told 'em to get stuffed. So they sued him. Judge told 'em if they couldn't keep their power in their lines they had no claim on it if somebody picked up and used what had leaked outside their right-of-way. Nyah-nyah. Power company said that doing this was dangerous. Farmer said he'd keep doing it regardless of their claims.

    Then the power company did a little switching of the line. This threw some big transients down it. The farmer's equipment arced over and burned down his barn.

    At least that's how the story went. It was a lead-in to a lesson on the problems of switching transients in power transmission lines. So I have no idea how much of it is apocryphal, whether there are precedents since, or how a judge might rule in a current case.

    But if I were to try it I'd make sure the lines were outside their right-of-way (so I could argue that if they didn't want to give away the power they should have bought enough of a right-of-way to contain it and put up shielding wire runs inside the boundary to keep it in - cheapskates exposing people to their EM fields etc.) and be sure to include surge arresters at the load end my wiring.

Loose bits sink chips.