[amsat-bb] RF, another alternate energy technology (hogwash)

Robert Bruninga bruninga at usna.edu
Fri Nov 8 07:37:46 PST 2013

A fellow came to me convinced that capturing RF energy from cell phones,
and radio and TV waves was free energy.  He couldn’t wait to invest in
these pocket sized antennas that have achieved the same 37% energy
reception efficiencies as do the most expensive solar cells:.


I told him to not believe everthing he hears  and  you Amsat radio guys
might get a kick out of my response:


Thanks for sending me this interesting example of hype gone ridiculous.  I
was glad to receive it.

The problem is apples and oranges.  Yes, they got ”37% efficiency, similar
to the most expensive solar cells”, but the difference is that solar energy
imparts about 100 watts of energy per square foot on a solar panel –
remember, ONE HUNDRED WATTS/sqft.

The amount of energy from a Cell tower onto a small antenna  1 mile away
from the cell tower (typical) is only 0.000000000004 Watts.  So there is
about a one hundred trillionth of the practicality.

Or another way to look at it.  If you could hold their RF energy collecting
antenna 1 inch from the cell phone tower (not one mile), to get more power,
then the most power he could get would be only 3 watts.  Still nothing
close to what the sun provides.  Plus, he would be absorbing all the power
from the cell phone tower making it useless, plus the energy is not free.
SO to get the same power as a palm sized solar panel, his RF capture
antenna would have to be ONE INCH away from THIRTY cell phone towers.

And,  to generate that same 100 watts worth of RF energy, it takes about
300 watts of electrical power. (1 inch away)

All to deliver about 1 Watt of power compared to the Sun which is free.

Thanks.  A great lesson in hype!

Bob Bruninga, WB4APR

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