Wire less power?

This was discussed in this group a while back.

The horribly mathematical paper from last november is at

Personally I wonder about the legal aspects of it. I don't know all the regulatory details but it seems to me that in the USA it would count as an intentional radiator under part 15 which sets a limit of 30uV/m at 30m at frequencys between 1.705Mhz-30MHz

I'd be surprised if it passed EMC testing for CE marking either.

Bob

"Bob"

Sounds unlikely to me.

.......... Phil

Phil Allison a écrit :

Well, they don't even have to exist...

Bob ha escrito:

Hello Bob,

I think you are right. I did a simple analysis based on the flux linkage between two single turn loops and the nearby B does exceed ICNIRP levels for general public:

I did not mention the radiated power in the posting, but a single turn coil with D= 0.91m (3ft, the 2ft in my posting is wrong) will have a radiation resistance of about 200e-9 Ohm (at 600 kHz). I calculated that the resonant current would be in the range of 40A (single turn coil).

This would result in a radiated power of about 320uW (most optimistic result). At 30m, you may expect about 44dBuA/m (still in near field).

However when some other conductor is present (mains wiring, reinforcement steel, etc), the radiated power can be significantly higher as that other conductor will radiate also. This problem happens often in RF Electronic Article Surveillance equipment (EAS). Those are also inductive loop systems

Best regards,

Wim PA3DJS.

hmm it is very interesting.

About 2 or 3 years back, I saw a mat style object that you just put on the table in the kitchen and when you get home each day, you just throw your moby, mp3 player etc on this mat and it recharges them all with only a single PSU... thus dispensing with a plethora of chargers. It was a huge flat coil that would induce in the same way as conventional transformers. Inside your chargees (it's a word now :o) you would have to have an induction coil and regulation etc... a useful posit was that such equipped devices could provide incidental charging from existing fields so charges would last longer by "scavenging" from the fields around us every day.

Definately possible, but it needs a lot of co-op from research/design/manufacturers and you have to keep the health lobby happy about radiant emissions etc. It might take a while.

It should have stayed lost.

Gee, Hertz, Marconi and others knew this crap a few years ago or so....