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

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: William Beaty <billb@xxxxxxxxxx>

On Wed, 14 Sep 2005, Tesla list wrote:

> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
> G-line is not a simple wire.  It has a dielectric coating (usually
> polyethylene) on the outside and the launchers establish a radial
> electric field which then propagates with low loss on the outside of the
> highly conducting center conductor to the receiving "launcher".  Can't
> imagine any such action with the earth because it's so lossy and the
> dielectric constant of the atmosphere is indistinguishable from one.

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.

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.

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.

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 essentially how the "director" elements of
a Yagi antenna work: they absorb and re-radiate the incoming waves but
with phase delay, so the row of "director" elements acts like a dielectric
rod made up of giant resonant atoms all in a row.  Also I've seen articles
about microwave waveguides based on dielectric rods, where the rod is much
thinner than a quarter wavelength, so the microwave field is mostly
outside the rod, yet is still guided by the rod. Sort of like "optical
fiber," but with the fiber thinner than a wavelength of light.


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William J. Beaty                            SCIENCE HOBBYIST website
billb at amasci com                         http://amasci.com
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