Startup claims 1W wireless charging at 10 metres

"a 2.4 GHz unlicensed transmitter has a maximum power of 4 W"

No - there is no limit (as per EU law) on the transmitter power. However there is an ERP limit...

Schmokin'

Reminds me of a story about cattle behaving strangely in a field adjacent to GEC Telecomms transmission systems research unit at Binley. Early Microwave test transmissions were being beamed across a field between a dish mounted on the team's ubiquitous garden shed and a small tower.

Farmer contested that his cattle became sterile.

Maybe these devices are the answer to the world's need for population control.

Total pass.

No thanks. What hell is wrong with some Qi mats?

That burning smell

You would hope there would be some sort of regulations about how many of these could be installed within range of each other. While the article talks about 1 "charger", what happens if your premises puts one in, the shop next door installs one, too - as well as a utility device in the shopping centre and possibly another in the offices above the public area.

A few of these, close together could give the Walkie Talkie building a run for its money in the death ray charts if multiple chargers all locked on to your (pocketed) iPhone at the same time.

Tesla would be proud!

Wireless energy transmission, yeah, he thought of that.

Witricity

A company formed out of MIT research uses resonant magnetic coupling to achieve this. They have some cool demo videos and some cheap kit you can buy for a great science lesson if you are a teacher.

I do get it. Phase alignment of an array of transmitters. I'm sure it will work as stated with one exception. While I'm sure it's highly improbable that a second point of phase alignment will occur, highly improbable happening with sufficient frequency means it's certain to happen.

Even if you don't believe it yourself. What happens when the wireless charger is on and the phone is in your pocket?

When tissue is already at core body temperature, it doesn't take much extra heating to cook it.

erp limits

Last time I checked the erp limit at 2.4gig is +20dBm, or 100mw. You are not going to get much power at 10m or even 1m.

Even if they can raise the power above the regulatory limits they then hit the power safety limits as defined by ICNIRP which are designed to stop you cooking the user.

Whole thing looks like snake oil, even if it works it won't be legal to use in most of the world.

Correct me if I'm wrong, but...

If I stick a 1W solar cell on the back of an iphone and then put it on a desk under a big light, then it's basically the same shit as this?

Hmm....

The free space attenuation at 2.4GHz is 60dB, so to get 1W over the area of an antenna is going to require an ERP at 10m of 1MW...shirley?

Sounds like a death ray from Danger 5!

Stoopid...

Why didn't they they grab a cheap and cheerful microwave oven and jigger the door interlock so that it'll transmit 600 watts on 2.4 GHz for a total cost of $50?

This is in addition to the *many* other layers of stoopidity inherent in this concept.

Why pay more for a device producing power at 2.4Ghz, just bung your new iPhone 5P (plastic) in the microwave and see if it charges.

On test by PC plod?

Almost sounds like a cut price Taser to me.

2 more things not to forget:

How much would this end up costing just to charge your phone? Thanks to all of the inefficiencies, you can watch your bill skyrocket.

Also, what happens to your phone and its battery when it is trying to charge it all day long? One of the biggest drains on a batteries life is using your phone while it is charging. This is also what causes it to get extra hot.

Yea. I'm going to continue to pass on any form of wireless charging. It's ok, I can manage to plug my phone into a cable while I sleep.

yes you can.

The limits are per Transmitter so while you may not be able to have more than 4w from an antenna with whatever gain you put on the antenna if you then make 100 transmitters and had the ability to focus that into the same point from all transmitters you could get 400watts at a receiver 1m away.

Nokia had a much better solution back in 2009. The best part of the Nokia design, you didn't have to buy the wireless charging transmitter. It didn't charge the phone at 1W and a wired charger was still required at times. What they did do, use the ambient radio waves already being transmitted to help charge the phone. This would mean longer standby times but eventually you would need a wired charger to fully charge the battery. But as processors get more power efficient, eventually the power generated by the ambient radio waves could be enough to charge the phone and maybe even enough to fully power it while it is being used.

"The system collects energy from ambient radio waves emitted by antennas, TV masts, Wi-Fi transmitters, and the like." So it is not even picky about the band it uses.

There are some people on here that have as much idea about RF as this "inventor".

Having 100 transmitters connected together does not simply give you 400W. It gives you 100 4W signals.

Do you understand fourier analysis? Go work it out... Also Vsum=V1+V2=Asinωt+(-Asinωt)=0

Using one transmitter and 100 combined 36dBm amplifiers would get you 400W, but that's actually still a single 400W transmitter then and not legal.

The FCC in the US permit 30dBm (1W) into a 6dBi gain aerial for point to point links = 4W EiRP.

For general use, the FCC and the EU rules are the same = 20dBm EiRP.

Not sure if it's still the case, but France used to be 13dBm EiRP.

Exceeds safe limit for microwave exposure

Focusing a few watts of microwave power onto something about 5cm on a side results in a power density several times the accepted 0.01 watt per square centimeter safe limit for human exposure.

Geoffery Landis at NASA came up with this idea over a decade ago, and it's patented under US patent #6,967,462. The Ossia patent is just a few tweaks on the Landis patent. The safety issue was described in the Landis patent. That patent proposes detecting backscatter when the beam hit something other than a properly tuned antenna (such as a human) and reducing the power until the human gets out of the way. That might work, but it's iffy from a safety perspective.

At laptop scale, this might work, because the target area is bigger and the energy density of the beam can be reduced by using a wider beam. But charging phones while people are wearing them? Bad idea.

There's no problem doing this. Microwave power transmission has been demonstrated many times. It's just that you don't want people in the beam.

How many?

Regulation issues aside, I have 10 or more candidate devices at home that would benefit from this technology. A busy Starbucks could easily have 40. He didn't address how to deliver 1W to each of them simultaneously.