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Author Topic: Newbe HF antenna grounding question  (Read 644 times)
KJ4LKF
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Posts: 8




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« on: March 15, 2010, 08:05:36 PM »

I just purchased a multi band sloper antenna,with an end feed.The instructions say to keep the feed end as close to the earth as possible.Now 2 problems arise ,1-keeping it stealth from the HOA spies and 2 -a non fenced backyard and small children living next door who may want to see what that new shiny wire is ,so more for safety ,I'll have to mount it on the backside of my roof.The question is ,having to keep the ground wire as short as possible,would I still have a good enough ground if I run a ground wire to my alum gutter,then at ground level,put in my steel rod and run a wire from the rod to the bottom of my Alum downspout.Other wise my ground wire will be about 15 ft or so, from the antenna down the side of my house to my the gound rod. I'm wide open for suggestions.
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KZ1X
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Posts: 3229




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« Reply #1 on: March 15, 2010, 08:13:20 PM »

You didn't mention what antenna, specifically, you have, but in any case:

1.  If the 'ground' wire is part of the antenna, as I suspect, elevating it will radically alter the antenna design parameters.
2.  If that isn't the case, and your 'ground' wire is a safety ground of some type, I'd make a pretty strong argument that what you propose is unsafe practice in a profound way.

Please provide more information about the specific antenna you have so that a more thorough/accurate answer can be offered.
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K9YLI
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Posts: 878




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« Reply #2 on: March 16, 2010, 08:07:35 AM »

as for using the  gutter as part of the ground cicuit.   why??   metal is metal and that would not change  from just running copper wire direct from the antenna to the ground rod.   As in   COPPER  ground rod.
if you can put one end of the sloper at  say   7 feet, then no one can catch their hat on it and kids cant reach it. as for them touching the ground wire, same as touching the ground  (dirt).
likely  insulated  copper wire anyway..
other than that,  what directions did you get with the antenna, or its  design from a book etc. ??
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K9YLI
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Posts: 878




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« Reply #3 on: March 16, 2010, 08:11:16 AM »

you say 'keep the feed end as close to earth as possible"
didnt say  any thing about grounding it there.
just that it should slope   'up' away from the feed point..  not feed high up and sllpe down hill toward ground.
I only know about one type of end fed antenna and the feed cable  justs ends at the feed point, as in  coax shield, just stops there and the center conductor
attaches to the  antenna..
but there may be other designs.
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K8KAS
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Posts: 570




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« Reply #4 on: March 16, 2010, 08:16:20 AM »

These 1/4 wave sloppers are a current fed antenna and NEED a good RF ground, that is, NOT a simple ground rod. Connect the ground to 5 or 10 radial wires (20 to 30 Feet long) placed on the ground would be a good start. I pin my coax and radials down to the grass/ground with sod pins. With in a month or two you can't even find the wires/coax. I would try to hide a simple 1/2 wave dipole and not use a ground dependent type of antenna if you want performance that is. Ham radio without a good antenna is not much fun in my book.  73 Denny K8KAS
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VA7CPC
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Posts: 2414




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« Reply #5 on: March 16, 2010, 08:18:51 AM »

. . .
if you can put one end of the sloper at  say   7 feet, then no one can catch their hat on it and kids cant reach it. as for them touching the ground wire, same as touching the ground  (dirt).
likely  insulated  copper wire anyway. . .

That "ground wire" carries as much RF current as the "hot" wire!  When the rig is transmitting, somebody who touches it will get a nasty RF burn.

                 Charles
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K4SAV
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Posts: 1851




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« Reply #6 on: March 16, 2010, 09:08:37 AM »

The only antenna I know of that is being sold as a "sloper" is a 1/4 wavelength wire.  Half wave slopers are sold as dipoles.  Slopers were intended to be mounted on a tower so that the Yagis could provide the other half of the antenna, but you can mount them at the ground using a good radial system.  It then becomes a monopole antenna (commonly called a vertical).  It doesn't have to run exactly vertical.  The less radials you have, the poorer the antenna will be.  A ground rod instead of radials should dissipate about 60 to 70% of your power in the ground, but it should produce a good SWR.

You can't attach this to anything else and then run a wire to ground.  That will produce an off-center-fed antenna and it won't resonate anywhere near where it was designed for.  The radials have to start at the antenna feedpoint.  If the feedpoint is elevated, the radials have to be elevated and resonant on the band of operation.

Jerry, K4SAV
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NR4C
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Posts: 312




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« Reply #7 on: March 16, 2010, 09:33:52 AM »

If I had it to do over again, the first thing I'd do before I bought a commercial antenna is to get hold of the most current available ARRL Antenna Book.  It csan be bought for around $50 but is often in the public library.  Even an old one is very useful.  Then, you cna spend as much as you want on wire and stuff.  The 'Book' has lots of stuff on antenna and feed systems to choose from.  Get a spool of wire and have fun.


...bc  nr4c
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AD4U
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Posts: 2186




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« Reply #8 on: March 16, 2010, 09:39:54 AM »

Congrats on the upgrade.  You can try the sloper and see how it works, but as someone who has been hamming 40++ years, I suggest that you try a "stealth" 1/2 wave dipole on a band or two.  I think you will make many more contacts and in the long run you will be happier with it.

As I said, try the sloper.  If you are happy with it, then OK.  If you are not try the coax fed 1/2 wave dipole.  It needs no radials, no ground plane, and no tuner.

Dick  AD4U
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