Re: Goubou line, "G-line" (was Tesla Coil RF Transmitter)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"Heh!  You're wrong, since experiment beats theory: if the wave-guiding
effect was real, wouldn't it be used?  It's used today.  The military
maintains a network of tranceivers all over the USA, spaced at 200miles
apart, running at 150KHz (2000 meters), each with an electrically short
100 meter transmitting tower .  Go search on GWEN, Ground Wave Emergency
Network.  The system is a fall-back comm channel in case the satellite
network is shot down, and it's designed to work even if a large number
of
the GWEN towers are blown up in a nuke war.  It relies on the idea that
the vertically-polarized VLF "ground waves" waves launched broadside
from
a groundplane antenna will follow the Earth's surface, and geography
details which are smaller than a few hundred meters will effectively be
invisible"

Bill:

	The name tells it all.  Ground Wave.  Fairly lossy transmission and
they ran a lot of power to make sure of getting through.  GWEN has been
off the air for many years, a boon to those of us with LF beacons in the
160-190 kHz band.  Commercial BC stations rely on ground wave
transmission for their primary coverage.

"In this G-line stuff, what's important is the wave-guiding "restoring
force" which makes the waves follow the conductor even if the conductor
is
slightly curved.  If the "force" was weak, then waves would only follow
the wire if it was curved very gently.  The curve of the earth is only
130 feet of deflection for each 10 miles traveled If Tesla managed to
"launch" some vertically polarized VLF waves out across the earth, would
they follow the earth or fly out into space?  They're KNOWN to bend
around the Earth, at least the 150KHz waves do."

	Follow the earth of course.  Just that the transmission is very lossy,
even over sea water.  Fully and correctly explained in Zenneck's
"Wireless Telegraphy", first edition (in German) 1906.

"The old articles on UHF/microwave G-line setups showed that the G-line
didn't need to be straight; it could be bent with a many-inches radius
curve over tens of degrees over several feet... But only if they added a
thicker dielectric coating to the cable: a plastic rod about 1" across.
Without the thick plastic rod, only a larger radius bend was allowed.
What happens with no dielectric at all? I received email from an
engineer claming that G-line still works fine if you don't use a plastic
coating, and also claiming the math shows that resistive effects in the
metal will create a wave-guiding effect.  (So a superconductor wire
wouldn't work?) But he didn't quote me any papers that go into this
rigorously."

	First part correct and practical installations often used (still use -
the stuff is still around) nylon or dacron cords to support the cable at
the bends.  As for the no dielectric bit, I'd like to see the papers.

"It does make sense though, since any rod which slows the waves below c
will also tend to focus them slightly inwards toward the rod, which
keeps them following the rod. "

	That's the way ground wave propagation works.  The old illustrations
show the waves "leaning" in the direction of propagation.

Ed