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Nearly 125 years late, wireless recharging arrives	by subbywan	2008-08-22 08:58:19
Wireless recharging is easy.	by AndyA	2008-08-22 09:14:33
75%-90% isn't a bad start. (n/t)	by subbywan	2008-08-22 09:17:44
At three feet.	by bwkaz	2008-08-22 09:35:23
I think you are missing something.	by AndyA	2008-08-22 10:33:58
Take your assumption and the known numbers - The power received is drops as the inverse square law. At 3 feet it is 75% efficient. So at 1 meter (I bet it really was 1 meter and was translated to 3 feet for the US media) if we transmit 4 watts we will get 3 watts. Inverse square means that at 1/2 of that distance we will get 4 times the power or 12 watts. Spot the problem yet? Inverse square law doesn't apply because this is using the magnetic near field to transmit power, inverse square is for the electrical far field. Once you get out of the near field (how far that is will depend on the frequency they are using) the power will probably drop at a rate of r to the fourth. Basically this is a transformer with a gap in the middle. And yes they will be directional antennas, probably wire loops with one of more iron rods pointing through them at the other antenna.
[ Reply ]
... Dang, yeah, you're right.	by bwkaz	2008-08-22 12:19:21
On the other hand:	by bwkaz	2008-08-22 12:22:42
If you lower the frequency then	by AndyA	2008-08-22 13:22:54
Hmm; that could be the intent.	by bwkaz	2008-08-22 13:26:47
But it could also "universalize" recharging.	by merlin	2008-08-22 13:31:11
Could... but won't	by Menetlaus	2008-08-22 13:45:38
but less cables = good.	by AndyA	2008-08-22 13:59:43
Maybe the average consumer.	by bwkaz	2008-08-22 14:20:44

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