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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."
Another great example as to how Tesla has shaped our future. Truly ahead of his time by leaps and bounds.
They also reduce the power of the signal for everyone else further away from the transmitter, reducing the range of the signals. If deployed widespread into cellphones, this could result in a non-trivial reduction in signal range for broadcasters in the harvested frequency range.
But if they sequester a range of frequencies specifically for wireless power usages....
Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
Where do you put your mobile phone when not in use?
Exactly.
One that hath name thou can not otter
I'll stop putting my phone in my pocket the moment someone proves that this "possible harm" is anything more than luddite hysteria.
Do you know how incredibly inefficient a power broadcast system would be?
Do you know the rate at which said power broadcast would drop off with regards to range?
Simple physics.
"... if 1 Megawatt gives you 6 milliwatts..." That's off by a factor of 1,000. One megawatt gave 6 microwatts.
The Nokia press release says they are expecting almost 10,000 times 6 microwatts, all received inside a tiny cell phone that is covered with metal.
I'm sorry but that has got to be one of the dumbest ideas I've seen in a while. The lack of power efficiency of this would make a fleet of Hummers look green in comparison.
What you suggest is deliberately sending out EM energy for these devices to pick up and recharge. The EM waves don't travel directly to phones; they travel in all directions from the tower. I don't know the exact equations, but for a cell phone a couple of miles from a tower you can count the zeros in the efficiency numbers. Tesla experimented with this idea, but found that the efficiency made it not feasible over any worthwhile distance.
To respond to grandparent's post, there is the possibility it could result in a non-trivial reduction in signal strength. However, I'll bet our use of aluminum and steel in large quantities for buildings, roads, and bridges have a larger effect today (as one constraint is the size of the device).
That's insane.
What do you think they're going to do, block the entire airways between the buildings with cellphones? Most of the radiation is going to miss the phones *and* the buildings.
Would that be cheaper to do than sticking a solar cell on the phone?
Excuse me, but please get off my Pennisetum Clandestinum, eh!