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[RFI] wireless power transfer via 160M band

To: rfi@contesting.com
Subject: [RFI] wireless power transfer via 160M band
From: Dennis Monticelli <dennis.monticelli@gmail.com>
Date: Wed, 7 Feb 2018 09:30:05 -0800
List-post: <mailto:rfi@contesting.com>
This has been researched in the universities.  MIT made some PR on it
several years back.  My former employer was close to this research
activity.  The idea is for the receiver to be in the near (induction) field
of the transmitter and tuned to the exact frequency.  But in order to get a
decent throw distance some serious power is required and the efficiency of
capture is low.  Where does the wasted power you ask?  It does into heat,
it goes into nearby wiring, it gets radiated for hams to pick up.  BTW,
most wireless charging does take place after dark when people return home
and/or are sleeping.

I suggest that the ARRL take the lead in determing the noise signature of
this particular experiment and make that info available to the amateur
community so we will know when we receive it. Without reports of
intercepted interference the FCC will not act.

Generally it is just a carrier with some low bit rate modulation that feeds
back sync info to the transmitter.  If the receiver and transmitter do not
have their hi Q circuits locked the power transfer efficiency is very low.
There are schemes that adjust the TX and there are schemes that adjust the
RX or RX's.  The wavelength must be long enough for a receiver to be in the
induction field regardless of where it resides within the home but not so
long that it is impractical to have efficient tuned loops, hence the desire
for 160M.

BTW, I have no knowledge of the scheme that this Texas company is using.
It may be different.

Dennis AE6C
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