Nokia prototype recharges batteries with radio waves
 

http://tech.yahoo.com/blogs/null/143945

Nokia, however, has taken another baby step in that direction with the invention of a cell phone that recharges itself using a unique system: It harvest ambient radio waves from the air, and turns that energy into usable power. Enough, at least, to keep a cell phone from running out of juice.


While "traditional" (if there is such a thing) wireless power systems are specifically designed with a transmitter and receiver in mind, Nokia's system isn't finicky about where it gets its wireless waves. TV, radio, other mobile phone systems -- all of this stuff just bounces around the air and most of it is wasted, absorbed into the environment or scattered into the ether. Nokia picks up all the bits and pieces of these waves and uses the collected electromagnetic energy to create electrical current, then uses that to recharge the phone's battery. A huge range of frequencies can be utilized by the system (there's no other way, really, as the energy in any given wave is infinitesimal). It's the same idea that Tesla was exploring 100 years ago, just on a tiny scale.


Mind you, harvesting ambient electromagnetic energy is never going to offer enough electricity to power your whole house or office, but it just might be enough to keep a cell phone alive and kicking. Currently Nokia is able to harvest all of 5 milliwatts from the air; the goal is to increase that to 20 milliwatts in the short term and 50 milliwatts down the line. That wouldn't be enough to keep the phone alive during an active call, but would be enough to slowly recharge the cell phone battery while it's in standby mode, theoretically offering infinite power -- provided you're not stuck deep underground where radio waves can't penetrate. Nokia says it hopes to commercialize the technology in three to five years.

Re: Nokia prototype recharges batteries with radio waves
 

What I keep wondering is how the set will know if it's 'unnecessary' EM energy, or, in other words, how do you prevent such a device becoming a radio (wifi, bluetooth, etc) jammer/sink ? :)

Re: Nokia prototype recharges batteries with radio waves
 

Maybe it will use the back of the phone for cell connection and front of the phone to suck EM waves... or maybe brain waves? :D

Re: Nokia prototype recharges batteries with radio waves
 

I'm still really not all that impressed with the wireless charging and power systems. While the concept is good, they're grossly inefficient by nature. Now an application like this however might be a better use for such a system. But then the next question arises. While there's enough EM radiation to make this work well in urban environment, what about rural areas where there's not much of any EM radiation to speak of?
Well, if they did that, it'd have the advantage of partially shielding the user from cellular radiation, while reclaiming part of the energy lost due to someone's big fat head being in the way of the signal. ;)

Re: Nokia prototype recharges batteries with radio waves
 

the physics involved?

a jammer is a active transmitter that sends a stronger signal then the one you want to recieve.

as for it being a sink, you will need a wall of phones more or less, and stand in the direct "shadow" of that wall.

best way to envision it is like a thin piece of fabric in front of a lamp. it may produce a darker area on the opposite wall, but it will not darken out the whole room unless you basically wrap it around the lamp...

Re: Nokia prototype recharges batteries with radio waves
 

That really depends on the frequency. Even without human sources you will have SOME EM radiation everywhere. Now, if you're not near short-range pesky microwave sources, the ones who might curse you for leeching will be cellular operators, radio stations, terrestrial TV stations, wimax folks, basically anyone who does long-range wireless communications.

PS. The idea is not really lab-tech - I remember making detector/crystal radios when I was a kid, those were simple shortwave receivers that were getting both signal and power through antennas. Cool stuff (even by todays standards), but when harvesting EM waves, you want BIG ANTENNAS :)

Re: Nokia prototype recharges batteries with radio waves
 

Nokia try to recharge battery by wave around instead built a photovoltaic device...

that's a weird orientation lol

Re: Nokia prototype recharges batteries with radio waves
 

yah! put a big transmitter near a dam then every house having a big antenna to receive electricity so we can have wireless electricity!

Re: Nokia prototype recharges batteries with radio waves
 

Almost, although it's not related to power - it means decreasing signal to noise ratio of a signal (altough done by emission most of the time as it's the easiest way of achieving that goal). I admit being somewhat free with the terminology ;)

No, it doesn't work that way, unfortunately :) Radio waves propagate differently than light - that's why you use antennae that are very different, to, say, optical telescopes. Of course, the actual difference varies with the frequency, but it's far from the lamp example -> it's a bit like a magnet drawing metallic particles, the affected area is much larger than just the actual antenna. Now, if these buggers want to harvest a consistent 50mW out of thin air, they HAVE to cover a large area, not just a 'speck' on the back of the set (either that, or we're already glowing in the dark :) )

Re: Nokia prototype recharges batteries with radio waves
 

heh, the devil will as always be in the details.

still, EM waves are EM waves, no?

got to confess tho, im a curious amateur when its comes to a topic like this one...

Re: Nokia prototype recharges batteries with radio waves
 

Yes, but unfortunately TFA does not specify the size/configuration of the receiving antenna. Also, doesn't say that the charger is supposed to be part of a phone - it sounds to me more like a self-powered base-station with a spiderweb/collector back... 5 or 50 mW are just numbers in the air until we see the antenna and the distance/power of the EM source. 50 mW sounds just too much to me for something very pocketable under generic indoor conditions...

Disclaimer: my EE skills are a bit worse than rusty, mostly ghost memories from my HAM and college days, even though I pick up the good ole soldering wick from time to time :)

Re: Nokia prototype recharges batteries with radio waves
 

It's the next best thing to perpetual motion!

Next: a motion-driven power generator in every cell phone. Come on, it's inevitable! Like self-winding watches!

Re: Nokia prototype recharges batteries with radio waves
 

Oh, and tweeted at least twice now! Thanks jself for the info (although I already knew this was coming, just didn't know when)

Re: Nokia prototype recharges batteries with radio waves
 

This initiative will fail (again) - because there is no way how to charge end users for energy that they use (the old story with Tesla will repeat again).

I hope that I am wrong and our society is mature enough for such inventions.

Regards

Re: Nokia prototype recharges batteries with radio waves
 

The difference to Tesla's problem is that there is no 'provider', so payment is not expected anyway.

Re: Nokia prototype recharges batteries with radio waves
 

Not quite true Radio waves propagate exactly the same way as light, but you need different materials to absorb them and convert the EM "light" into electrical energy

Re: Nokia prototype recharges batteries with radio waves
 

If under 'same way' you mean 'can be described with the same equations and laws of physics', you are correct. However, that still means vastly different reflection, refraction, diffraction, absorption, interference (etc etc) characteristics depending on wavelength. Not really just a question of materials. That's why for example solar cells are not antennas, it's just not 'practical' at that wavelength.

Re: Nokia prototype recharges batteries with radio waves
 

Not really ... energy of the waves will be absorbed by those devices and probably this will lead to bad communication or video signals for "wave providers" - so they will need to increase their signals (for information http://www.livescience.com/environme...e-weather.html). And this leads to bigger amount of energy used to create waves and bigger charges for real consumer for those waves and of course a lot more wave power will be spread around and this may cause even some medical problems to people.

And finally bad thing will be that instead of saving energy this will increase energy consumption and even if there is no direct "wave provider" that will charge you, this charges will be paid by someone - usually all of us.

I am so not(positive)

Regards

Re: Nokia prototype recharges batteries with radio waves
 

Yes, that concern was raised in my very first post to this topic :)

Re: Nokia prototype recharges batteries with radio waves
 

not by a long shot, sadly. these days one wants payment for subjects that would get one labeled a conman a couple of generations ago...

Re: Nokia prototype recharges batteries with radio waves
 

Actually, the amount of energy absorbed by a typical cell phone is 0.0000001% of the total signal strength. Absorption rate is directly proportional to the size, density and material makeup of the object. A cell phone itself would absorb such a minuscule amount of energy that it wouldn't be missed. They already do that to a degree now anyways. The biggest offenders in the area of energy absorption is trees, buildings, cars, people, etc. Cell phones are small beans in the greater picture. So if these did have the wireless power thing, they wouldn't really change the current signal conditions.
A couple of generations ago, people were less gullible and more careful with their money. Surplus cash flow and ease of income has made people lax, and thus more easily conned. It's a funny thing really. The more money someone has, and the more comfortable someone becomes, the easier they seem to be conned. If you're not comfortable with your current money situation, you're a whole lot harder to sucker.