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Nokia Developed Wireless Power-Harvesting Phones
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."
"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 ago...it 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.
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.
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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.
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 http://en.wikipedia.org/wiki/Heinrich_Hertz. 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.
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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.
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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.
http://michaelsmith.id.au
They're not "drawing" power from the antenna. They're just scooping up some of the power that's already being splashed around.
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