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Author Topic: Radials for a 75 meter vertical  (Read 774 times)
K3MOV
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Posts: 504




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« on: August 02, 2002, 06:24:41 PM »

I am considering putting up a vertical that covers 75/80 meters. The research that I have done so far makes it very obvious that I should have a good number of radials if I expect to have decent performance. Unfortunately, my geographical set up is not going to allow that. My question is this, since I don't have the horizontal space to put down any radials, would it help my efficiency if I were to place four ground rods four to eight feet deep around the base of the antenna or would 4 be no more helpful than a single rod? Thanks for your help.
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K3MOV
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« Reply #1 on: August 03, 2002, 02:19:40 PM »

Thanks for the reply. Perhaps I didn't phrase my predicament properly.

I do not have enough space to run even one "radial" perpendicular to the base of the antenna. I was wondering, therefore, if I were to pound several 4 foot or 8 foot copper "rods" in the ground immediately next to and parallel to the base of the antenna, the lack of regular perpendicular "radials" would be somewhat offset.

Based on what I have now read, I would be wasting my copper and energy.

Other opinions are, of course, welcome
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WB2WIK
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« Reply #2 on: August 05, 2002, 06:56:17 AM »

Surely improving contact with earth below the antenna is a good thing, and better than nothing.  I've had reasonable luck with multiple-rod ground systems, with the rods bonded to each other and also to the vertical antenna base using very LARGE gauge conductors, like 2" wide copper flashing, to minimize ground resistance and inductance.  #6 wire doesn't work well.

Remember, if you could sink a single ground rod directly into the earth beneath the antenna, and that rod were 65' long (and deep), your vertical would now be a center-fed vertical dipole and its efficiency would be only about 3dB down from a center-fed vertical dipole (because half of it is buried and not capable of radiating) -- not bad!

Obviously, you can't sink a 65' deep ground rod.  But using multiple ground rods and bonding them well together, and keeping the earth moist (daily sprinkling from an automatic sprinkler works!) does certainly help.  

WB2WIK/6
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K3MOV
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« Reply #3 on: August 05, 2002, 07:33:44 AM »

Thanks for the interesting reply. Please see the responses to my same subject entry under "Elmers" for some different opinions. Thanks, Tom
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WB2WIK
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« Reply #4 on: August 05, 2002, 09:14:49 AM »

I did read those, and elected not to add to that mess.  Most of the opinions posted there weren't particularly relevant.

My post above isn't much about opinion -- it's a practical answer based on actually doing it (using multiple ground rods and watering them, in lieu of a radial field, on 80 meters).

73 de Steve, WB2WIK/6
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