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Now researchers from North Carolina State University and Carnegie Mellon University say they have hit upon a way to boost the efficiency of the energy transfer in that [wireless transfer] situation. They reported, in a paper published in the online edition of the journal IEEE Antennas and Wireless Propagation Letters, that by placing a magnetic resonance field enhancer (MRFE)—a loop of copper wire resonating at the same frequency as the AC current feeding the transmitter coil—between the transmitter and receiver coil, they could boost the transmission efficiency by at least 100 percent. "Our experimental results show double the efficiency using the MRFE in comparison to air alone," David Ricketts of NC State, said in a press release. The MRFE increases the strength of the magnetic field that reaches the receiver coil, resulting in an increase of the transmission efficiency.
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For their experimental setup, the team used two coils of 4.25-centimeter- diameter copper wire with six turns for the transmitter and receiver coils. The coils were separated by 12.2 cm and the transmitter coil was powered with a 2.94-megahertz signal. They measured the transmission efficiency by placing a metamaterial between the transmitter and receiver coil and comparing it with a setup where a single, 12-cm-diameter copper-wire loop replaced the metamaterial. They found that the copper wire version improved the efficiency by a factor of almost two.
Does wireless charging solve any problems that an industry-adopted connector standard wouldn't?
(Score: 2, Insightful) by Francis on Monday August 03 2015, @03:49PM
The main reason I used to have a wireless charger was so I wouldn't have to plug my phone in to charge it.I could just set the thing down and not worry about charge.
But, it also means that you can completely seal the phone, so you can get real waterproofing for applications that need it. You also don't wear through the durability on your devices as quickly and if it's dark, you don't have to turn on the light or worry about damaging the jack if you don't put it in quite right.
(Score: 2) by frojack on Monday August 03 2015, @04:12PM
But at what cost?
Does the wireless charger consume (radiate, leak) power when the phone is NOT there?
No, you are mistaken. I've always had this sig.
(Score: 2) by Francis on Monday August 03 2015, @04:19PM
A properly designed system isn't going to be transmitting constantly, that would be wasteful. Radiation shouldn't be a concern beyond the wasted electricity. The system I was using used conductors to tell the device to turn on and the actual charging was wireless.
The main reason I'm not still using it is that you had to buy a special adapter for each phone since they weren't standardized and there wasn't one for my new phone. Eventually they got bought and rebranded by one of the battery companies, but I definitely miss the convenience of just being able to set the phone on the charger.
(Score: 0) by Anonymous Coward on Monday August 03 2015, @04:29PM
> Does the wireless charger consume (radiate, leak) power when the phone is NOT there?
Everything I've read says no.
But just to be sure I put a kill-a-watt meter on the wireless charging cradle [amazon.com] for my hp touchpad and it measured, before, during and after putting my touchpad on the cradle - the results - 0 watts, 9 watts, 0 watts.
Based on the so pleasant convenience of wireless charging, I will never buy another daily-use phone or tablet that does not have wireless charging.
(Score: 1) by dr zim on Monday August 10 2015, @02:11PM
Good point there for the phone and I guess that would apply to a lot of other things, too.