Dear Bill, LF Group,
At 12:41 15/05/2003 -0400, you wrote:
Hmmm. This ridiculous over-concern with 1w ERP could be turned around...
As a concerned US citizen, why not take the following scenario to the Dept
of Homeland Security:-
If you were deliberately setting out to cause trouble, then rather than
using a normal radio antenna, more efficient coupling of LF power to
overhead transmission lines could be achieved with a horizontal loop of
wire directly underneath the overhead wires. Marry this with an LF power
source capable of putting several hundred watts into the coupling loop
(several tried and tested designs exist...), and interference currents will
be generated far larger than anything feasible from proposed amateur
operations. Furthermore, such equipment can easily be made portable so that
it could be positioned anywhere along hundreds of miles of transmission
lines, and could be easily concealed to the point where even an intensive
search of the area probably wouldn't find it. Very little radiated signal
would be produced in the far field, so D/F techniques would be little use
in locating the equipment either.
Thus, a small number of terrorists with a budget of a few hundred dollars
each to spend on perfectly mundane, locally available, electronic
components could shut down the US grid at will and at very little personal
risk, effectively holding the entire nation to ransom.
Of course, if anyone actually tried it, it probably wouldn't have the
slightest effect 99.99% of the time - but if the utilities were to claim
that, they would be directly contradicting their position over 136kHz. If
they stated that their systems had somehow been upgraded to be immune to
this type of attack, then they would also be protected against amateur
radio transmissions, and their objections to the 136kHz allocation would
again evaporate.
There is a power line not far from my QTH which continuously radiates a
136.65kHz carrier - I'm almost tempted to go and try it; after all, it
would be perfectly legal here. So if you hear I was dragged away by tall
gentlemen in dark suits with short haircuts, you will know what happened... :-)
Cheers, Jim Moritz
73 de M0BMU
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