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Complete clean scan of paper by A. Doty Jr. on buried radials v. elevated




 
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Author Topic: Complete clean scan of paper by A. Doty Jr. on buried radials v. elevated  (Read 7010 times)
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K5UJ
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« on: July 01, 2009, 08:02:58 PM »

Performance of Conventional Buried Wire Radials versus Elevated Insulated Radial Wires Used as Ground Systems for Vertical Antennas / Archibald C. Doty Jr.

18 November 1983



For a few years I have had a paper copy of this 14 p. monograph by Archibald C. Doty Jr. on radials.
I can't remember how I came to possess it, but I have been unable to find it on-line so I have scanned it and now make it available for download. 

Abstract:  Approximately 50,000 miles of bare wire has been buried in the United States as radials under commercial and amateur radio station antennas in an effort to provide the most efficient artificial ground systems possible.  A recently concluded research program indicates that buried bare wire radials do NOT provide optimum performance.  Rather, the investigation indicates that wires comprising an artificial ground system should be elevated for maximum efficiency, and if it is necessary to bury these wires for practical or aesthetic reasons, INSULATED wire should be used.

http://home.fnal.gov/~atkinson/Doty-Radials.pdf

Update:   I have upgraded the file above by adding the previously missing page 3.  I have also rescanned the paper using PaperPort and cleaned it up considerably and increased the resolution.  It is about 800K in size now as a pdf and looks better than the original copy I used for the scan. 

7/9/09 73 Rob K5UJ
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« Reply #1 on: July 01, 2009, 09:41:30 PM »

I've need told 1/3 of the global copper supply is in use and 2/3 is in the ground. half in mines and half in landfills. It is as well to not bury any more..

and Thanks much for making this available to us!
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« Reply #2 on: July 02, 2009, 12:02:04 AM »

I agree with the paper except for one thing.  I don't think it makes any difference whether buried radials, or radials lying on top of the ground, are bare or insulated.

Insulated wire will last longer because the plastic insulation protects the copper from corrosive minerals in the soil.

Besides providing the "mirror" for the image antenna, you can think of the ground radial system as a shield to isolate the radiating antenna from the  lossy earth.  It follows logically that the farther away the ground plane is elevated from the earth, the more effective the shield will be, and fewer wires will be needed.  Also, by burying the radials, you have a thin layer of lossy earth between the radiator and the ground plane, so burying the radial wires partially defeats the whole purpose of the ground plane.  However, the loss is negligible if the radials are buried no more than a couple of inches into the ground.  The only purpose for burying the radials is to protect them from damage by surface traffic such as humans, animals, lawn mowers, vehicles, etc.

I have a pre-WW2 ARRL antenna book in which they recommend burying the radials a couple of feet into the ground; I don't know if that was a typo and they might have meant inches.  Besides reducing the efficiency of the ground plane, imagine how much work it would take to bury 120 quarter wave radials on 160, two feet underground.
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« Reply #3 on: July 02, 2009, 12:17:03 AM »

I agree with the paper except for one thing.  I don't think it makes any difference whether buried radials, or radials lying on top of the ground, are bare or insulated.

Insulated wire will last longer because the plastic insulation protects the copper from corrosive minerals in the soil.

Besides providing the "mirror" for the image antenna, you can think of the ground radial system as a shield to isolate the radiating antenna from the  lossy earth.  It follows logically that the farther away the ground plane is elevated from the earth, the more effective the shield will be, and fewer wires will be needed.  Also, by burying the radials, you have a thin layer of lossy earth between the radiator and the ground plane, so burying the radial wires partially defeats the whole purpose of the ground plane.  However, the loss is negligible if the radials are buried no more than a couple of inches into the ground.  The only purpose for burying the radials is to protect them from damage by surface traffic such as humans, animals, lawn mowers, vehicles, etc.

I have a pre-WW2 ARRL antenna book in which they recommend burying the radials a couple of feet into the ground; I don't know if that was a typo and they might have meant inches.  Besides reducing the efficiency of the ground plane, imagine how much work it would take to bury 120 quarter wave radials on 160, two feet underground.

Hi Don, thanks--I want to apologize for the size of the file.  I am going to try to work out a new way of scanning these things so the resulting file is smaller. 

I like this paper only because my inverted L radials are all insulated no. 14 solid, laying on the ground (except by now they have sunken in a bit) and like any other antenna phool I'll grasp at anything that will make me feel good about taking the lazy way out.  Grin  But seriously, I know some b/c stations bury to prevent theft in addition to the reasons you gave.  There's one guy in the industry who recommends putting them down _five or six feet_.  I can't remember what they do to get them that deep but his reasoning is that you'll never have to worry about copper theft when they're that deep.  I know ground penetration of RF varies with frequency--I guess the lower the frequency the deeper the penetration (which must be why those submarine commo systems are so low) so 5 feet deep might be okay for under 1 MHz but it might not work for hams, as if a ham would do such a thing.  Oh, I guess another advantage to going a bit deep up here in the north is to prevent ground heave from pushing them up during freeze thaw cycles.

Anyway, there are a zillion papers on radials but this one had an interesting point I thought and as far as I know had not been widely circulated so I thought I'd add it to the radial signal to noise.

73

Rob K5UJ
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« Reply #4 on: July 02, 2009, 12:30:40 AM »

BTW, I have  talked to Harry, K4HU, many times on 160 and 75/80.  We have discussed the topic of radials at considerable length.  I'm not sure if he isn't SK by now, since he was getting up in years last time we talked, and that was at least 10 years ago.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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« Reply #5 on: July 02, 2009, 04:15:53 PM »

BTW, I have  talked to Harry, K4HU, many times on 160 and 75/80.  We have discussed the topic of radials at considerable length.  I'm not sure if he isn't SK by now, since he was getting up in years last time we talked, and that was at least 10 years ago.

It can be hard to tell now with licenses being good for 10 years.  I am attempting to contact Mr. Doty, now that I think I have some information about him, and make sure he doesn't mind my putting his paper up on a server.   I had tried to find him before but was unsuccessful.  Since there was no copyright statement on the paper I thought it would be okay but now I think I have a way to contact him so I'll try to get the missing page 3.  If everything works out, I'll rescan the paper and make a smaller file that I hope will print better.  There's a learning curve to just about everything.

73

Rob K5UJ
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