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Old January 3rd 16, 07:39 PM posted to rec.radio.shortwave
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Yes that old chestnut, but things do seem to be getting very bad now, at
least here in the UK.
The power line adaptors to pump internet signals around the mains for
houses, which seems a crazy idea to me, cause a nasty ticking noise with
hash and occasional screaming noises at all frequencies from just above the
160m ham band up to 32 MHz or so with of course the noted filters of the
ham bands, but not the broadcast ones!
then there are cheap and nasty 'wall warts' ie switch mode psus that knock
out burbles and whines that wander about all over the place modulated by
the mains frequency

Some laptop psus are even worse. most are made in China as are the devices
with internal noise generating circuits such as TVs and answering machines
etc.

Now come the led and cfl lights with their very naff power supplies as well
and the only thing it seems one can do is move to the middle of a field
somewhere, which is not terribly convenient or indeed possible on cost
grounds, and even if you do, you would never get planning permission for a
large aerial farm now would you?

With the medium and long wave transmitters in Europe being turned off bit by
bit, it seems the powers that be have admitted defeat.
Sadly though, even vhf and uhf are not immune to the modern devices. A
number of popular wifi routers seem to knock out rather nasty stuff from
about 60 MHz up to over 600 in the same house as they are installed. lack of
screening and nasty waveforms presumably being the main cause with a nice
cable and mains connection to act as an aerial.

So, here in this new year, I do hope somebody can see some sense and design
equipment that does not act like a noise transmitter.
People, mostly the tin foil hat brigade have been banging on about the
unhealthiness of mobile phones and their masts for years, but inside the
home we must surely slowly be building up rf fields now that would scare
these people if they realized what was going on.
There is no place to hide folks!

Brian

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Old January 5th 16, 03:59 PM posted to rec.radio.shortwave
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Default Interference

If radio frequency wireless charging ever takes off, interference will
be orders of magnitude worse.
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Old January 8th 16, 09:02 PM posted to rec.radio.shortwave
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No it does not work and is very inefficient even using microwaves as it
heats up the water vapour in the air.

Brian

"analogdial" wrote in message
...
If radio frequency wireless charging ever takes off, interference will
be orders of magnitude worse.


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Old January 14th 16, 06:29 PM posted to rec.radio.shortwave
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Brian Gaff wrote:

No it does not work and is very inefficient even using microwaves as it
heats up the water vapour in the air.

Brian


Yes, it works (basic Tesla stuff, after all) and it's expected to
use frequencies up to a few megahertz, not microwaves.

"For IPT applications of several kilo-Watts such as
charging electric vehicle, energy efficiency higher than 90%
is possible. For low-power wireless charging of mobile
phones (up to 5W), typical system energy efficiency
exceeding 70% can be achieved. For these modern short-
range domestic and industrial applications, the operating
frequency is usually in the range of 20 kHz to a few Mega-
Hertz"

http://hub.hku.hk/bitstream/10722/18...t.pdf?accept=1

This is magnetic resonant coupling used at distances within one
wavelength. I have a strong suspicion that the low shortwave
frequencies will be the first target because 1) the wavelengths are
suitable and the receiving coils will be minimized 2) they will want to
keep the interference out of the MW broadcast band 3) the politics
favor the charger users over the SW radio users.

I'll speculate that these things will be allowed to be significant
harmonic generators up to the TV band.




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