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Nokia Developed Wireless Power-Harvesting Phones

samzenpus posted more than 4 years ago | from the tesla-would-like-a-word-with-you dept.

Cellphones 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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246 comments

fo (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#28286785)

falc U first post

Need More (3, Funny)

yo_tuco (795102) | more than 4 years ago | (#28286805)

Wake me up when it can harvest 1.21 gigawatts

Re:Need More (5, Funny)

jd2112 (1535857) | more than 4 years ago | (#28287105)

It's called a lightning rod, although a clock tower and a sufficient length of cable will work in a pinch. Figuring out how to get lightning to strike a DeLorian while traveling at 88mph is left as an exercise for the reader.

Re:Need More (2, Insightful)

master5o1 (1068594) | more than 4 years ago | (#28287229)

is left as an exercise for the reader.

What, I must have cheated when I watch this documentary about time travel several years ago.

Crazy Idea - during his time... (3, Insightful)

SevenHands (984677) | more than 4 years ago | (#28286807)

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

Re:Crazy Idea - during his time... (1)

geekoid (135745) | more than 4 years ago | (#28286849)

Tesla invented radio?

Re:Crazy Idea - during his time... (1)

SydShamino (547793) | more than 4 years ago | (#28286883)

Yes?

Re:Crazy Idea - during his time... (2, Funny)

sexconker (1179573) | more than 4 years ago | (#28286919)

Macaroni?

Re:Crazy Idea - during his time... (4, Funny)

victim (30647) | more than 4 years ago | (#28286931)

They are asking about radio, not noodles.

Re:Crazy Idea - during his time... (2, Informative)

sexconker (1179573) | more than 4 years ago | (#28286965)

Re:Crazy Idea - during his time... (2, Funny)

MBCook (132727) | more than 4 years ago | (#28287085)

Your own reply points out the joke victim made.

Macaroni vs. Marconi

Re:Crazy Idea - during his time... (1)

sexconker (1179573) | more than 4 years ago | (#28287131)

I made that joke.

Re:Crazy Idea - during his time... (2, Funny)

Anonymous Coward | more than 4 years ago | (#28287155)

Yes, you did - but you lost all the points you made for the joke by getting into an argument about who made the joke.

Re:Crazy Idea - during his time... (3, Informative)

geekoid (135745) | more than 4 years ago | (#28287089)

No.

Mahlon Loomis used radio for wireless transmissions in 1868. about 25 years before Tesla.

Tesla created a circuit for doing it, but he wasn't the first and it isn't the only way.
Cool boat, tho'.

Re:Crazy Idea - during his time... (0)

Anonymous Coward | more than 4 years ago | (#28287307)

After reading into Loomis' contributions, I can say without a doubt that what Loomis did was insignificant compared to what Telsa did.

Re:Crazy Idea - during his time... (1)

Accursed (563233) | more than 4 years ago | (#28287317)

Allegedly he did, but nobody was there to witness it. I'm not sure that counts.

Henrich Hertz (4, Interesting)

SuperBanana (662181) | more than 4 years ago | (#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 http://en.wikipedia.org/wiki/Heinrich_Hertz [wikipedia.org] . 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:Henrich Hertz (5, Informative)

Accursed (563233) | more than 4 years ago | (#28287145)

It's more an electrochemical signal, though, not really anything to do with the energy of radio waves. It's electrical in the sense that it's charged (ions), not in the sense that there's an actual stream of electrons moving along like wires.

Crystal radio (5, Informative)

davidwr (791652) | more than 4 years ago | (#28286809)

Crystal radio sets [wikipedia.org] harvested enough power to drive an earphone-sized speaker.

In some circumstances, florescent light bulbs can draw enough power from a nearby power source to light up.

Re:Crystal radio (3, Insightful)

HTH NE1 (675604) | more than 4 years ago | (#28286875)

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....

Re:Crystal radio (2, Insightful)

sexconker (1179573) | more than 4 years ago | (#28286925)

But if they sequester a range of frequencies specifically for wireless power usages....

No one would use them for broadcast, and thus, no "free" energy to suck up.

Re:Crystal radio (2, Insightful)

HTH NE1 (675604) | more than 4 years ago | (#28287023)

But if they sequester a range of frequencies specifically for wireless power usages....

No one would use them for broadcast, and thus, no "free" energy to suck up.

Someone would: the people using it for power for their wireless communication devices. They could just have it broadcast dead air (silence) or white noise, though they'd likely figure out a suitable signal that maximizes the power that can be harnessed most efficiently.

Re:Crystal radio (1)

SomeJoel (1061138) | more than 4 years ago | (#28287101)

Someone would: the people using it for power for their wireless communication devices. They could just have it broadcast dead air (silence) or white noise, though they'd likely figure out a suitable signal that maximizes the power that can be harnessed most efficiently.

Well at that point, you'd just use a conventional charger. I think the point is "free" power - if you have to broadcast it yourself it would be even more expensive than a normal charger.

Re:Crystal radio (3, Insightful)

sexconker (1179573) | more than 4 years ago | (#28287147)

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.

Re:Crystal radio (0)

Anonymous Coward | more than 4 years ago | (#28287333)

simple to understand - yes
physics - yes

simple physics? not necessarily... if you're an accomplished physicist, probably, your're average /. reader may not think so.

Huh? (3, Informative)

wsanders (114993) | more than 4 years ago | (#28286943)

Most of that power would be absorbed by some material, nearby concrete, or ground.

Re:Huh? (1)

CarpetShark (865376) | more than 4 years ago | (#28287441)

Precisely, a lot is lost to buildings etc. And now they're talking about harvesting the rest, between the buildings, where people with phones are.

Re:Crystal radio (1)

mikael (484) | more than 4 years ago | (#28287225)

So do buildings, mountains, vegetation and people. All of these are going to be absorbing electromagnetic radiation.

Re:Crystal radio (1)

ls671 (1122017) | more than 4 years ago | (#28287319)

"They also reduce the power of the signal for everyone else further away from the transmitter" seems impossible to achieve specifically.

Signal strength varies at 1/square of the distance of the transmitter, there is no possible border defined by "for everyone else further further away from the transmitter" where the signal strength could suddenly drop compared to everyone on the other side of that theoretical border.

I might have missed something although. If so, please clarify how they "reduce the power of the signal for everyone else further away from the transmitter" I suspect this could be possible with a dedicated frequency for each user and the transmitter varying the strength for each frequency depending on distance which would be found by sending echo packets between the transmitter and the user (which has to transmit too) although it seems at first counter-intuitive to do something like that. Is that what you were saying ?

Re:Crystal radio (2, Interesting)

artor3 (1344997) | more than 4 years ago | (#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.

What is the CEO of Nokia doing? (1)

Futurepower(R) (558542) | more than 4 years ago | (#28287057)

"In some circumstances, florescent light bulbs can draw enough power from a nearby power source to light up." In that case, the nearby power is huge.

From the Slashdot summary: "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." Six microwatts from 1 megawatt is about right.

The estimate of "50 milliwatts" from ambient radiation to charge a cell phone is not. Remember that cell phones are generally inside buildings or inside pockets or purses while someone is driving.

That statement is so crazy that it makes me wonder what the the CEO of Nokia is doing. Doesn't he realize he should stop nonsense like that?

Re:What is the CEO of Nokia doing? (2, Insightful)

neokushan (932374) | more than 4 years ago | (#28287179)

Presumably, they're relying on the fact that you're very rarely within range of just ONE transmitter. I'm going to assume that the following maths are bad, but if 1Megawatt gives you 6miliwatts from 4.1Km away, then is it unreasonable to assume that if you're 2.05Km from that same transmitter, you could get 12millwatts?
And getting back to the first point, what if there's more than one transmitter nearby? Cellphone stations, radio towers, TV transmitters and so on - it's bound to all add up in some way. No doubt this technology would be completely useless for those who are in the country or less "dense" areas, but for the people who live in or near the City, it could probably reach that figure with ease.

Or a different way to look at it - right now, there's a lot of "potential" energy floating around that's just going to waste. Technology like this could make use of it and when distributed on a large scale could feasibly save the economy a hell of a lot of money.

Microwatts, not milliwatts (3, Insightful)

Futurepower(R) (558542) | more than 4 years ago | (#28287227)

"... 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.

Re:What is the CEO of Nokia doing? (1)

TinBromide (921574) | more than 4 years ago | (#28287191)

Yeah, I wonder how much energy passes through the human body in an average developed area. We are transparent to radio waves, but I'd love to see how many micro/milliwatts pass through our skin. I wouldn't be surprised if you add up all man made signal types (ignoring EMF from electricity lines, appliances, and the like) would be less than 1 milliwatt if you're not really near a tower. Sure you could run a long line antenna along your roof to suck up that power, but why bother? You'd probably have to keep it up and running for years to pay for the materials/work to get it set up.

The body is more than 60% water. (1)

Futurepower(R) (558542) | more than 4 years ago | (#28287271)

"We are transparent to radio waves..."

The human body is mostly water [madsci.org] mixed with salt, which is conductive and therefore opaque to radio waves.

I agree with you. The total amount of energy is tiny, especially when tiny antennas are used.

Re:What is the CEO of Nokia doing? (1)

gringofrijolero (1489395) | more than 4 years ago | (#28287315)

We are transparent to radio waves...

Only the lower frequencies. If we were transparent, X-ray photographs would be blank.

Re:Crystal radio (3, Interesting)

MichaelSmith (789609) | more than 4 years ago | (#28287127)

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 (0)

Anonymous Coward | more than 4 years ago | (#28287233)

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.

I see what you did there.

Re:Crystal radio (1, Funny)

Anonymous Coward | more than 4 years ago | (#28287339)

I have geraniums but they don't act as radio receivers, nor transmitters. They don't appear to make noise either. They just grow up until they're spindly because I forget to nip the buds out. Nice red flowers though.

Re:Crystal radio (1)

MichaelSmith (789609) | more than 4 years ago | (#28287427)

I googled it and got a hit on geranium diodes. Maybe so many people make the same mistake that google is useless for spell checking.

Re:Crystal radio (1)

ls671 (1122017) | more than 4 years ago | (#28287421)

There is indeed quite a bit of power available at close range since the strength varies at 1/square of the distance.

The local TV station had a desperate guy jumping the fences and climbing on top of the transmitter tower with the intention of jumping. They immediately shutdown the transmitter while police were dealing with him. They finally got him down after 4 or 5 hours although he was exposed for a brief period of time.

Apparently, the guy would have cooked in a microwave like fashion had they left the transmitter on.

Once lived *really* close to AM transmitter... (1)

Mr. Roadkill (731328) | more than 4 years ago | (#28287399)

For a short time, I lived within a couple of kilometres of an AM transmission tower. A pair of vintage high-impedence headphones, a high-power rectifier diode and an earth were all I needed to listen. I was toying with the idea of home-made detectors (galena, iron pyrites, rusty razor blades and a piece of lead etc), but moved before I got around to it.

Re:Crystal radio (0)

Anonymous Coward | more than 4 years ago | (#28287575)

can I charge it in my microwave oven???

didn't Tesla do this decades ago? (0)

Anonymous Coward | more than 4 years ago | (#28286811)

And people have been known to "steal" power remotely from high power transmission lines in a way I don't recall (or understand).

Re:didn't Tesla do this decades ago? (1)

calmofthestorm (1344385) | more than 4 years ago | (#28287029)

If it's not coaxial then you just make use of the fact that the moving electric current induces a strong magnetic field outside the cable. Forgot my vector calculus but by placing wires/inductors in the correct configuration it would leech power off the power lines through the magnetic field.

Re:didn't Tesla do this decades ago? (2, Interesting)

HTH NE1 (675604) | more than 4 years ago | (#28287063)

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

Re:didn't Tesla do this decades ago? (1)

ls671 (1122017) | more than 4 years ago | (#28287487)

Hmmm.. Not sure those people were actually steeling, I open the question for debate.

Can a device like the ones we are discussing actually "pull" more power from the source if present ?

Or would a device like this impact be limited to depraving downstream users from the energy they catch ?

Thanks in advance for answers ! ;-)

See, Tesla really isn't nuts! (0)

Nabeel_co (1045054) | more than 4 years ago | (#28286829)

And they said that Tesla was nuts. Jeez, just because he spent all his time at dinner calculating the volume of food on his plate, It doesn't mean he's crazy... Although that is pretty crazy...

Still waiting (-1, Offtopic)

basementman (1475159) | more than 4 years ago | (#28286865)

I'm still waiting on the dozen or so cures for cancer that have been announced in the past week.

Why not solar? (3, Interesting)

j0se_p0inter0 (631566) | more than 4 years ago | (#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 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.

Re:Why not solar? (4, Insightful)

sznupi (719324) | more than 4 years ago | (#28286895)

Where do you put your mobile phone when not in use?

Exactly.

Re:Why not solar? (2, Informative)

j0se_p0inter0 (631566) | more than 4 years ago | (#28286929)

Well yeah, I thought of that. But if my battery was low and I didn't have a charger, simply leaving it in a windowsill or something would be a pretty handy feature.

Re:Why not solar? (-1)

HTH NE1 (675604) | more than 4 years ago | (#28286953)

Where do you put your mobile phone when not in use?

Exactly.

Yeah, even though they make holsters designed to keep them the safe distance away from the body to avoid any possible cancerous effects from constant exposure, men still put them in their pockets.

Women tend to put them in purses.

Re:Why not solar? (4, Insightful)

Nursie (632944) | more than 4 years ago | (#28287037)

I'll stop putting my phone in my pocket the moment someone proves that this "possible harm" is anything more than luddite hysteria.

Re:Why not solar? (2, Informative)

sznupi (719324) | more than 4 years ago | (#28287211)

Interesting...the holsters disappeared from here long time ago. They were only somewhat popular at the very beginning of cellphone availability...mostly as a pseudo status symbol.

I don't miss them at all.

Re:Why not solar? (1)

HTH NE1 (675604) | more than 4 years ago | (#28287275)

Mine broke. I bought a cheap replacement, it broke. I don't bother anymore and also keep it in my pocket or on a nearby surface (usually nowhere new sunlight, put possibly under indoor lighting).

Re:Why not solar? (0)

Anonymous Coward | more than 4 years ago | (#28287347)

Big, bulky brick phones - that's what the holsters were needed for. Now mobiles are small, thin and light - they fit comfortably in normal pockets, rendering redundant the holsters.

Re:Why not solar? (2, Funny)

winomonkey (983062) | more than 4 years ago | (#28287449)

Um, I guess that I am technically putting it in a place where the sun doesn't shine. Are you saying that I shouldn't be doing that if I want to take advantage of your proposed solar wonder?

Cellphone Range (0, Redundant)

klingens (147173) | more than 4 years ago | (#28286891)

Won't that decrease signal range of cellphone towers? If all the phones in the vicinity power themselves from the tower's signal, that signal can't travel as far as before, leading to needing more towers per square mile, no?

Re:Cellphone Range (0)

Anonymous Coward | more than 4 years ago | (#28286947)

As they are harvesting your current account, isn't it fair to harvest their tower's signals? I bet the red numbers won't be on their side.

Re:Cellphone Range (2, Insightful)

pluther (647209) | more than 4 years ago | (#28286981)

Which leads to more power to harvest.

Which leads to more devices developed to harvest it.

Which leads to more powerful signals.

Which leads to Tesla's dream of sufficient power being broadcast wirelessly to run all of our electric devices. For free! Woohoo!

(Well, either that, or the amount it takes from the signal is so tiny as to not make any practical difference...)

Re:Cellphone Range (2, Funny)

MBCook (132727) | more than 4 years ago | (#28287571)

Don't be ridiculous. This is America.

You'll have to select a power company and only get power from them. They'll find some way to track your usage (probably an electric chip on the device which... requires power).

Now to keep power sorted out right, each company will get their own frequency. It will be against the SDMCAaPDA (Super-DMCA and Puppy Disbursement Act) to explain to anyone the concept of an antenna or a diode, as those could be used to steal power.

But don't worry, they'll make the power broadcast towers look like 50 foot tall lamp-posts so they will "blend in" to the scenery and not be an eyesore.

Re:Cellphone Range (1)

FlyingBishop (1293238) | more than 4 years ago | (#28287051)

Maybe. But that might be an overall plus. It depends on how much energy is being reclaimed.

They have to build more towers, sure, but if 30% of the extra power is being reclaimed by the cellphones, then we have better coverage, and the phones are being powered by energy that otherwise would simply dissipate when it reached the edge of the tower's range.

Now, for shorter range wi-fi devices, it could be a little annoying, but I still feel like this is a good way to reclaim some of the energy lost in wireless communication. I mean, I have a wi-fi modem operating 24-7 (which is also my wired router), and I have no idea what kind of a field it generates for wi-fi. What I do know is that whatever power it expends on wireless is only in use for the 1-3 hours my mother is actively using her laptop Internet. (And I've set it up so she's using it fairly close to the modem.)

TV Antenna = Compact sensor (1)

Malluck (413074) | more than 4 years ago | (#28286905)

> 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.

Oh..... You mean the high def TV antenna.....

http://www.techonline.com/learning/techpaper/212902041

I do have to say the WISP project sounds neat. They're essentially RFID powered sensors.
http://www.seattle.intel-research.net/wisp/

Question. Won't this weaken the RF signal? (2, Interesting)

KefabiMe (730997) | more than 4 years ago | (#28286935)

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?

Re:Question. Won't this weaken the RF signal? (1)

Skapare (16644) | more than 4 years ago | (#28287173)

Maybe in the immediate area (size of antenna plus 1 to 2 wavelengths) there will be some signal disruption. But it won't have any affect at a distance. It isn't going to overload the transmitter.

Re:Question. Won't this weaken the RF signal? (1)

KefabiMe (730997) | more than 4 years ago | (#28287287)

Some numbers for my own comparison... KPWR [radio-locator.com] (A popular Hip Hop radio station in Los Angeles) transmitts 25,000 watts of power. This article claims that it can pull 50 milliwatts. If this technology became standard on all cell phones, 1 million cell phones in Los Angeles would be able to pull a collective 50,000 watts out of the air.

Re:Question. Won't this weaken the RF signal? (1)

TinBromide (921574) | more than 4 years ago | (#28287381)

the 1 million cell phones might have to form a contiguous dyson sphere to capture all of the energy from that 25,000 watt power supply. Its a good thing that there's more than just KPWR in this world though, otherwise this nokia guy's idea might never get off the ground.

Re:Question. Won't this weaken the RF signal? (4, Informative)

TinBromide (921574) | more than 4 years ago | (#28287241)

no more so than a bunch of radios tuning in. If an antenna or chunk of metal is between you and a signal, your signal quality will be degraded. If not, you have a virtual line of sight (or LOS via reflections from the ground, buildings, etc) and can receive like normal. Its like worrying about your lawn receiving less light because your neighbor has solar panels on his roof. If the panels were between you and your lawn, it wouldn't matter if they were generating power, or just made of plywood, your lawn would be in the shade, but since they're not, your grass will be just as green. Its not like these antennas suck up the power, it won't bend the radio waves towards it like a magnetic pole would affect magnetic fields.

Harvest motion energy as well (4, Interesting)

heretic108 (454817) | more than 4 years ago | (#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.

Re:Harvest motion energy as well (1)

sznupi (719324) | more than 4 years ago | (#28287237)

Yeah, that seems more practical when you're in the wild. Especially since the tech is already there - not only mechanical watches are able to wind themselves up, there were also some quartz ones obtaining their power that way.

In the meantime - carrying a phone like Nokia 1208 (ubercheap, standby mode of almost 2 weeks, with the biggest compatible batter probably 3) isn't a big problem when you want to be sure it's working...

Re:Harvest motion energy as well (1)

TinBromide (921574) | more than 4 years ago | (#28287301)

See, that's precisely what I thought when I read the title. I thought a wireless power-harvesting phone was a wireless phone capable of power-harvesting, most likely from motion or heat.

College experiments (3, Interesting)

get_your_guns (1380583) | more than 4 years ago | (#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.

Re:College experiments (4, Funny)

HTH NE1 (675604) | more than 4 years ago | (#28287129)

This is useful knowledge to have. Imagine being lost and in need of rescue. If you could create a device that siphoned sufficient power from radio signals to reduce their range, not only would you have power for a beacon but also the FCC would take care of tracking down your location so that you'd stop doing it.

Re:College experiments (0)

Anonymous Coward | more than 4 years ago | (#28287361)

If you could create a loop capable of tuning into an individual frequency, creating enough of a phase shift to make a dent in a megawatt signal from miles and miles away, and the OP was truthful about the phone call (or the professor was truthful about the phone call), you may as well just go whole hog and create your own transmitter. But nothing in all my dealings with RF signals and through my EE education would indicate that there is even a shred of truth in the GPp beyond that he created a loop that could light a very tiny (veeeeerry tiny) light bulb from ambient signals.

Re:College experiments (5, Informative)

Anonymous Coward | more than 4 years ago | (#28287265)

I call BS on the phone call. I think your prof may have been pulling your legs. For one thing, 60 watts is a drop in the bucket compared to megawatt transmitters, for another, radio waves behave like light waves, there isn't a return loop or any sort of return transmission involved in radio waves.

Not-so-green phone (1)

Leon Buijs (545859) | more than 4 years ago | (#28286999)

[...] 6 microwatts from a 1.0-megawatt TV antenna [...] Wow, how's that for an environmentally unfriendly record?

Re:Not-so-green phone (1)

calmofthestorm (1344385) | more than 4 years ago | (#28287043)

There's not a limit of one per world. My guess is multiple devices could use it.

Re:Not-so-green phone (1)

Leon Buijs (545859) | more than 4 years ago | (#28287325)

Sure, but you'd still need 16600 devices to use it to get 1 Watt of energy in place, of the 1000000 Watts you spend.. That's ridiculous, even if you don't give a hoot about the environment.

Re:Not-so-green phone (1)

NewbieProgrammerMan (558327) | more than 4 years ago | (#28287095)

Well, if (1) the TV antenna will be pouring out 1MW whether there's phones charging off it or not, and (2) charging your phone from the TV station eliminates one or more permanently plugged-in wall warts per cell phone, then, yes, I would think that's environmentally friendly.

Even if eliminating a couple of wall warts really doesn't help with pollution or anything, I would still like to have this sort of charger in my phone just for the convenience of not having to plug it in as often.

Title (1)

machine321 (458769) | more than 4 years ago | (#28287019)

This will be much better than my corded power-harvesting phone.

Re:Title (1)

shog9 (154858) | more than 4 years ago | (#28287079)

I donno... I wouldn't mind having a cell phone that i could plug into the landline to charge. If i could make free local calls while charging, that'd be a nice bonus!

800Mhz Trunked Radios (0)

Anonymous Coward | more than 4 years ago | (#28287133)

This sounds really bad if they don't limit the frequencies. Who is going to be responsible when this causes problems with the low powered (3W radios/~100W repeaters) 800Mhz trunked radio systems that Police and Fire departments use?

So when are those corporate CEOs going to ... (1)

Skapare (16644) | more than 4 years ago | (#28287139)

... figure out a way to force people to pay them money for this ambient background radio power? And how are they going to keep freeloaders from stealing it?

Ambient power? (0)

Anonymous Coward | more than 4 years ago | (#28287183)

50 milliwatts of ambient power? I don't feel so good....

Free!! (1)

crispin_bollocks (1144567) | more than 4 years ago | (#28287249)

Puts me in mind of the numerous (see Pop Sci and Radio & Electronics from the 50s) attempts to power submarines with the "free" power of the earth's magnetic field.
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