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Old December 2nd 05, 02:56 AM posted to rec.radio.shortwave
 
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Default A very odd feedline.

I tried to post a mention of a very odd feedline called the "G-line"
Two attempts and google ate both of them.

It is a true single conductor UHF feedline.
It isn't perfect, but has a low loss.
It "leaks" and in some situaiton that is a benifit.

See:
http://w5jgv.com/1970_tower/tower.htm
http://www.broadcast.net/pipermail/radio-tech/2004-February/049867.html

I have used the damn things, they can't work, but they do.
They work very well.
I still don't believe in them.
But since they do appear to work I will pretend to believe in them.

Before flaming me, so some net research.
+"G-line" +"antenna"

Terry

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Old December 2nd 05, 06:06 PM posted to rec.radio.shortwave
johan aeq
 
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Default A very odd feedline.

It is in the Rothammel book too

schreef in bericht
ps.com...
I tried to post a mention of a very odd feedline called the "G-line"
Two attempts and google ate both of them.

It is a true single conductor UHF feedline.
It isn't perfect, but has a low loss.
It "leaks" and in some situaiton that is a benifit.

See:
http://w5jgv.com/1970_tower/tower.htm
http://www.broadcast.net/pipermail/radio-tech/2004-February/049867.html

I have used the damn things, they can't work, but they do.
They work very well.
I still don't believe in them.
But since they do appear to work I will pretend to believe in them.

Before flaming me, so some net research.
+"G-line" +"antenna"

Terry



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Old December 3rd 05, 05:17 PM posted to rec.radio.shortwave
Tom Holden
 
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Default A very odd feedline.

wrote in message
I tried to post a mention of a very odd feedline called the "G-line"
Two attempts and google ate both of them.

It is a true single conductor UHF feedline.
It isn't perfect, but has a low loss.
It "leaks" and in some situaiton that is a benifit.


In my final year of undergraduate engineering, I did a project for a
professor on a surface wave transmission line. While my project was not a
stellar success, it was interesting reserach. One application he had in mind
was to run a line beside a railway track and use time domain reflectometry
to track the location of trains. The idea was that the large train body
would affect the dielectric and electrostatic environment near the line,
cause greater leakage and the radiation would be reflected back onto the
line.

A surface wave transmission line is a waveguide, the complement of a
cylindrically enclosed waveguide.

Tom


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Old December 3rd 05, 07:07 PM posted to rec.radio.shortwave
 
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Default A very odd feedline.


Tom Holden wrote:
wrote in message
I tried to post a mention of a very odd feedline called the "G-line"
Two attempts and google ate both of them.

It is a true single conductor UHF feedline.
It isn't perfect, but has a low loss.
It "leaks" and in some situaiton that is a benifit.


In my final year of undergraduate engineering, I did a project for a
professor on a surface wave transmission line. While my project was not a
stellar success, it was interesting reserach. One application he had in mind
was to run a line beside a railway track and use time domain reflectometry
to track the location of trains. The idea was that the large train body
would affect the dielectric and electrostatic environment near the line,
cause greater leakage and the radiation would be reflected back onto the
line.

A surface wave transmission line is a waveguide, the complement of a
cylindrically enclosed waveguide.

Tom

------------------------------------------------
I installed a canadian desinged/built intrussion system that used
G-line instead
of "leaky coax". A pulse of microwave RF was sent down the line and
like RADAR,
anything man sized that was within ~20' gave a sharp/distinct return.
The analog
system could be tuned to ingore coyotes and dear. Worked very well.

A funny aspect of G-lines is that you can use aluminium wire. And after
the wire
has ozidesed some more it works better. I installed a 1000' Gline run
for a friend
on the back side of a hill that blocked TV from Lexington. It worked OK
when installed,
and got much better after about 2 weeks.

The losses at the start were comparable to low loss ladder line. But
after the 2 weeks
the losses went down. UHF channels of interest where 18, 27, 36, 46,
and 52. Still
working as of last weekend. We had to change the "feed line" after 15+
years. You do
have to keep trees/brush from growing into the "near field". He uses a
bush hog twice
a year to keep the path clear.

We tried to use it for FM, it did work, but the launchers got too big
and unwieldy.

One study I read suggested a "planer wave front" is formed between the
conductor
and an insulating layer. I did try a 100' run with bar copper wire and
it barely worked.

I still don't believe G-line can work, but I will continue to pretend
it does.

Did you get that link of a synchronous detector I sent you?
The hotmail account is dead. I had to give up on trying to fight
the spam. After getting several 100 hits a day I deciced it just
wasn't worth it.

Terry

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