Router can power your devices wirelessly from 15 feet away
engadget.com
engadget.com
Anyone remember this?
http://www.engadget.com/2010/01/09/airnergy-wifi-power-syste...
It just keeps getting weirder... this is starting to look more like fraud than your average startup-peddling-snake-oil.
If they aren't, they can still get 1W theoretically, which is actually useful: it can kind of charge your phone in 8 hours. Assuming 100% of the power is captured by the antenna, that is. (Note that I say theoretically: the real world is very bad for theoretical models.)
Also something to worry about: the FCC's maximum permissible radiation exposure. For 6 minute controlled application (people near the transmitter know it's on), you're allowed an energy density of 5mW per square centimeter. An iPhone 4 is about 55 cm^2, so that would mean a maximum of 275mW. That would charge the phone in 24 hours. (These are guidelines for amateur radio operators, not Part 15 devices; I don't know what the regs around Part 15 say about power density. The regs also cover far-field effects, not near-field effects, so perhaps they can get around these.)
Finally, if you want to play with beamforming and figure out how to get 100% of the power to a 55 cm^2 area, try: http://apenwarr.ca/beamlab/
"What are the RF spectrums being used by WattUp?" [1]
- 2.4GHz (Unlicensed) for Bluetooth Low Energy communication
- 5.7-5.8 GHz (Unlicensed Industrial, Scientific & Medical, ISM) band for power transfer"
(900MHz has a slightly difference RF exposure calculation that you have to do compared to 1300MHz and up. But 2.4 and 5 are the same.)
On HN:
https://news.ycombinator.com/item?id=7404884
And this one:
http://techcrunch.com/2012/07/11/disruptive-defined-ubeam-la...
On HN:
https://news.ycombinator.com/item?id=4232925
This is a weird bit in the article:
"To demo its tech, Energous has turned a casino suite into a faux home full of wireless power, which we dropped by to allow the company's founder Michael Leabman to put on a show for us."
If there is one thing that sets off my spidey sense during due diligence on new products it is demos in controlled environments.
> Power Delivered to a Consumer Full-Featured Product
> 4W delivered simultaneously to 4 devices, 0-5 feet
> 2W delivered simultaneously to 4 devices, 5-10 feet
> 1W delivered simultaneously to 4 devices, 10-15 feet
> Delivering on average 2W to 4 devices simultaneously within the charging envelope
Things that concern me are, in random order:
- Is it safe to keep the device (let say it's a phone) in a pocket or close to one's head while is it charging?
- Is it safe to sit/sleep for hours in between the charger and a (possibly somebody's else) device?
- How focused the power beam is?
- What are the safety measures to prevent other people stealing the power? Think about the family living on the other side of the wall. Probably Bluetooth pairing, but I'm not 100% sure.
- Does it cause reduction of bandwidth for WiFi? (it uses the same frequencies)
- Compliancy with regulations about electromagnetic pollution? They started the certification process in the USA for a receiver (http://www.energous.com/energous-completes-initial-fcc-part-...) but I'm more worried about the transmitter.
How quickly efficiency drops off.
I suspect you only get 70% if your phone is literally on top of the router, and that the efficiency drops of very quickly to 0 as you approach the range limit.
No, not really. I love my wireless charging pad it's as easy as putting my phone down, which I do when I'm not using it anyway.
I've been careless (charging a phone in my pocket) and broke several cables. The port is still rock solid.
Your health effects are very clearly in the [citation needed] area. The only negative effect from long-wave radiation (not gamma or UV) is that it heats things. If you heat a human too much, they die.
"A Federal standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts (mW) of microwave radiation per square centimeter at approximately 2 inches from the oven surface."
http://www.fda.gov/radiation-emittingproducts/resourcesforyo...
* Actually, we were using a Wi-Spy. No need for sensitive lab equipment to detect this much radiation.
Microwaves in the US are 1000-1500W or so. This tech apparently has a max of 16W. Conflating the two is like saying that because boiling water will burn you, it is dangerous to take a bath in lukewarm water.
We've had AM/FM transmission towers spread around the global transmitting at 100,000 Watts for decades, many in residential areas. Yet we have no conclusive evidence that there are negative health effects on those living next to them.
Tell me if it's 20 watts worth.
Oh, it was 2000 watts? Yes. Orders of magnitude matter.
>That stuff was discovered by Tesla ages ago
I'd give that distinction to Hertz on a practical level and Maxwell on a theoretical level. Honestly, I'm getting sick of the loudmouth Tesla fandom. His "internet celebrity" is largely ahistorical and detracts from real deserving and underpublicized scientists and engineers.