A Goubau Line

krokus

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Yes.... Thanks.... I was hoping it would give the dimensions in wavelengths though :(

Thanks
Joel
The wavelengths are in some of the other images on that page.

The way I see these lines working is basically giving a less resistant path through free space, especially when reading about the dielectric's affect on the wave.
 

prcguy

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The wavelengths are in some of the other images on that page.

The way I see these lines working is basically giving a less resistant path through free space, especially when reading about the dielectric's affect on the wave.
Its not giving a less resistant path through free space but it is keeping most (much? some?) of the RF on the wire because it is a transmission line. If it were through free space it would be subject to the inverse square law and RF will be four times less (6dB less) as you double the distance.
 

spanky15805

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I'm taking it as the insulation being the dielectric, just like in a mica capacitor, the dielectric is the insulation between the plates...

Wild right? (or I could be wrong, I'm depending on Lauri-Coyote-Frostbite to correct my errors at this point)

In the ARRL antenna book (an older one), it says that its important for the line be large and heavily insulated, such as #14 vinyl insulated.


Thanks
Joel
Yes sir, I understand what you are saying. I'm having a hard time trying to understand how vinyl is slowing down an electromagnetic wave. Is the vinyl doped with some type of metal powder? Lauri?
 

MUTNAV

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Its not giving a less resistant path through free space but it is keeping most (much? some?) of the RF on the wire because it is a transmission line. If it were through free space it would be subject to the inverse square law and RF will be four times less (6dB less) as you double the distance.
One of the ideas that is tough to swallow is how a non-conductive insulation on a wire is helping to keep the RF in... I like to imagine I completely get it, but I'm still trying to assimilate the information, and then apply the information to Rhombics, beverages, and other long wire antennas.


Like... could Lauri's feed also be used as MW receiving antenna at the same time.... (My guess is probably).
 

MUTNAV

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I just re-read Lauris post number 5.... If I understand part of it. the wire is 1/2 of a capacitor, free space is the other half, and the insulation is the dielectric, and as a capacitor, it doesn't really radiate.
 

prcguy

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One of the ideas that is tough to swallow is how a non-conductive insulation on a wire is helping to keep the RF in... I like to imagine I completely get it, but I'm still trying to assimilate the information, and then apply the information to Rhombics, beverages, and other long wire antennas.


Like... could Lauri's feed also be used as MW receiving antenna at the same time.... (My guess is probably).
Most of it is explained in post #5. For MW or HF reception or transmission the insulation and cones should be out of the circuit and the wire could be use but you would have to disconnect something at the far end to make the wire into a useable antenna.
 

prcguy

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I just re-read Lauris post number 5.... If I understand part of it. the wire is 1/2 of a capacitor, free space is the other half, and the insulation is the dielectric, and as a capacitor, it doesn't really radiate.
The inner surface of the insulation/wire junction would be one side of a capacitor and the outer surface of the insulation/air junction would be the other side of a capacitor.
 

MUTNAV

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I always found those old G line articles fascinating. It would seem there should be a niche market for them. For example, would the coupling loss be sufficient to use one as a leaky feeder in a tunnel radio system? Put cone launchers both ends, a repeater on one end and terminating resistor (or other antenna branch) at the far end?
In one of the links in the original article, (well dowstream a little), they had this..

g-line-community-television-radio-tv-system-news-november-1956-1.jpg
 

MUTNAV

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Most of it is explained in post #5. For MW or HF reception or transmission the insulation and cones should be out of the circuit and the wire could be use but you would have to disconnect something at the far end to make the wire into a useable antenna.
So are you saying that for MW/HF use, insulated wire shouldn't be used?

Thanks
Joel
 

MUTNAV

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BTW I'm loving this information, not often when something new (even though its "old") makes me re-think things like this (insulation on wire, really?).

Thanks Luari-Coyote-Frostbite

Joel
 

prcguy

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So are you saying that for MW/HF use, insulated wire shouldn't be used?

Thanks
Joel
No not at all. For a resonant MW/HF antenna the insulation will skew the calculated length very slightly but will have no other adverse affects on reception or transmission. The G-line is a transmission line and a completely different topic.
 

MUTNAV

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No not at all. For a resonant MW/HF antenna the insulation will skew the calculated length very slightly but will have no other adverse affects on reception or transmission. The G-line is a transmission line and a completely different topic.
Ok... not being a wise guy here, this is one of the things that was keeping me up....

Beverages aren't resonant, and if bi-directional aren't terminated.

A rhombic, with appropriate angles, could act like a cone (as far as a gradual impedance change, are we SURE that insulation doesn't effect it very much.

Are antenna models any good at modeling insulator and feed (both line and BALUN) effects?

I don't use a computer model program, but I'd love to know if they are that detailed.

Thanks
Joel
 

prcguy

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Ok... not being a wise guy here, this is one of the things that was keeping me up....

Beverages aren't resonant, and if bi-directional aren't terminated.

A rhombic, with appropriate angles, could act like a cone (as far as a gradual impedance change, are we SURE that insulation doesn't effect it very much.

Are antenna models any good at modeling insulator and feed (both line and BALUN) effects?

I don't use a computer model program, but I'd love to know if they are that detailed.

Thanks
Joel
I'm sure insulated wire on a Rhombic will only affect the calculated length of the wires slightly. A good computer program should be able to model insulated vs non insulated antenna wire just fine but not for a G-line, its not an antenna.
 

MUTNAV

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I'm sure insulated wire on a Rhombic will only affect the calculated length of the wires slightly. A good computer program should be able to model insulated vs non insulated antenna wire just fine but not for a G-line, its not an antenna.
Thanks, I appreciate the reply.

Are there feed line simulators that would be able to do a G-line accurately??

As a side note, I did some math for horn radiators awhile ago (90's), and its funny that some microwave frequencies, modeled (with the propagation being at the speed of light), and audio horns (like cheerleader megaphones) with propogation at the speed of sound, had pretty much the same size needs.

Also, parabolic dishes have a similar effect (which I was able to play with in technical school by whispering into metal radar parabolic dishes (FPS-77) , and at a museum at white sands which had parabolic dishes at ear height, spaced (a hundred?) feet apart that visitors could use to play with.

Come to think of it, waveguides and speech tubes (like on old battleships, or kids playgrounds), seem to have a similar effect (different means of operation, but with the same outcome).

Oh God... all of science is melding together !!!!

Thanks
Joel
 

6079smithw

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Errata---

I just re-read what I had copied and pasted above.... and would have laffed if I wasn't the serious scientific-type (grins ;) )

The diameter of the horns is NOT 914 inches ---76 feet........ mine are more like 28 inches, but I would have to measure them.


Geeeeez........ :(
If you have a 76-foot diameter horn, just use it as a megaphone from a hilltop. No radio necessary.
 

samcken

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I'm curious how it was decided that "pulling with a tractor" was not affecting the wire. Before I retired I worked with many types of wire but never came across a "tension" rating for common wire. While it may exist, I would be concerned about the characteristics of the insulation versus the wire as it stretched. (I'm assuming there was no parallel support wire in the run.)
 

Sheepdog777

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.


I have been meaning to write up this unusual topic for some time. Then a weather event this week brought it back in sharp focus with a snow storm and high winds. All night long this storm raged, and in the morning I was greeted by its twisted mass buried in a snow bank.
Caught your attention ? Well the twisted mess was a 600 foot run of #10 insulated wire that runs (ran :) ) from the peak of a barn up to the top of a towering granite escarpment that over-shadows my house. That escarpment was a wonderful shield against the elements for my great grand parents, but they built it long before there was any radio. It effectively puts me in a great semi-Faraday mountain cage for anything to the north.

That said, if I wanted to access any of the V/UHF ham repeaters in the valley to the north I would have to use a high gain antenna, swing it about to find the hot-spot on a mountain side --and bounce a signal out of my shadow.
I had thought of running a coax line up to the top of that escarpment, and put a beam up there, but the cable length with its feed line losses made that prohibitive.

Ah ! but what better reason to try a novel feedline- a Goubau line- than my "escarpment."

Better known as a "G-Line" (and no, that is not a "G-String" :) )- this feed line has been around since radio's beginnings. Yet it has been lost to time, at least to hams.

What is a G-Line ? ***

View attachment 138365


Simply put, its a single run of wire with two 'launchers' placed at both ends; it acts as a waveguide, and it is very effective at V/UHF frequencies. What is neat about this feed line is its extremely low losses--- while coax can be rated at so many dB's-loss per hundred feet, a G-Line is rated at so many dB's-loss per mile! ........The down size is they are just, really, mechanically, awkward..... This, making it pretty much a specialty item. But if its a situation requiring a lonnnng feed line run..........

In my case I was in luck to have some fellows at the machine shop at my lab fabricate the two launching horns for me. It took a bit of searching for the correct wire, for the dielectric on this wire acts much the same way to effect the forward wave like the earth's effect on low frequency "ground wave" signals.
The 'horns' terminate in standard 75 Ohm coax that feeds both the radio and a three-element commercial grade, wide bandwith beam.
We strung (and are going to have to re-string) -the wire by pulling it (Carefully!) taught with a tractor. It can tolerate some sagging, but it really wants to be straight. Sharp bends in the wire will induce losses, and also become radiation hot spots..

How does it work ?

Is Awesome a good technical term ?

_______________________________________________________________________________________________________________________________________________________-


I have no dB loss figures for this 600 foot run, but signals that were barely above the noise floor at the house (unless a beam was pointed at a mountain side as a passive repeater) -are 'full quieting" at the other end of the 'horn.'

Looking for an interesting project?


Lauri


View attachment 138367


*** The 'G-Line' Community TV System, November 1956 Radio & Television News

.
Absolutely love it! When we move out into the country and have some land... I am going to try this out. Reminds me of the old NVIS antennas we grounded with our Bayonets decades back. I'm a new Ham as far as my Ticket goes, but I'm diving into the deep end of the pool with ankle weights on researching underground antennas. Awesome topic and love your panache style.

o7
 

MUTNAV

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I'm curious how it was decided that "pulling with a tractor" was not affecting the wire. Before I retired I worked with many types of wire but never came across a "tension" rating for common wire. While it may exist, I would be concerned about the characteristics of the insulation versus the wire as it stretched. (I'm assuming there was no parallel support wire in the run.)
On a beverage, the support is usually something like sticks in the ground along the length, in the article about the cable tv system, it was supported with nylon string at the telephone poles.

Thanks
Joel
 

Sheepdog777

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Thanks, I appreciate the reply.

Are there feed line simulators that would be able to do a G-line accurately??

As a side note, I did some math for horn radiators awhile ago (90's), and its funny that some microwave frequencies, modeled (with the propagation being at the speed of light), and audio horns (like cheerleader megaphones) with propogation at the speed of sound, had pretty much the same size needs.

Also, parabolic dishes have a similar effect (which I was able to play with in technical school by whispering into metal radar parabolic dishes (FPS-77) , and at a museum at white sands which had parabolic dishes at ear height, spaced (a hundred?) feet apart that visitors could use to play with.

Come to think of it, waveguides and speech tubes (like on old battleships, or kids playgrounds), seem to have a similar effect (different means of operation, but with the same outcome).

Oh God... all of science is melding together !!!!

Thanks
Joel
Gonna Mess With Your Head a Bit...

IF: The Air is an Insulator
AND: The Ionosphere is a Conductor/Quasispherical Waveguide
AND: The Earth is a Conductor/Spherical Waveguide w/ Ferrite/Nickel Core
AND: All Transmission Lines & Antennas Are Conductors
AND: Transmission Line Theory is Very Similar to Electroacoustical Theory (Isobarics)
AND: RADIO IS MODULATION OF VOICE/DATA/CODE
THEN: Can the Earth Be a Transmission Line, Antenna, Electrically Driven Electrical Modulation Medium?

Think about that Huh....?

Until It Clicks... Here's a Combat Officer on a Unicycle... lol

Sweet Dreams...

Ryan, AE0TO
o7
 

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