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Author Topic: Easy radials for Field Day vertical?  (Read 6552 times)
KD8IWZ
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Posts: 56




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« on: September 26, 2010, 03:38:27 AM »

I'm starting to plan for Field Day 2011, considering setting up a vertical. I have a source for VERY inexpensive (free) surplus aluminum foil. I envision making my radial field of this foil, easy to install (held down by rocks, sticks, pinecones, etc) and easy to remove and properly dispose of. Am I on the right track, or is that a "too good to be true and probably is" brainstorm? All thoughts warmly welcomed.

73, Dale
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NI0C
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Posts: 2903




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« Reply #1 on: September 26, 2010, 05:10:03 AM »

VE3WMB has used such foil radials for his QRP field work.  See his web page:
http://www.qsl.net/ve3wmb/foil_gnd.html  for detailed info.

I can't say how well it works-- I'm still trying to catch him on one of his QRP field expeditions to Gatineau Park (one of my favorite X-C ski areas).

73,
Chuck  NI0C
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N4NYY
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« Reply #2 on: September 26, 2010, 06:34:44 AM »

Ugh. I would stay away from that. Based on wind, foot traffic and such, I would think it would be a pain in the neck. I would stick the multiple wires.
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KE3WD
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« Reply #3 on: September 26, 2010, 08:13:02 AM »

I've used the lawn and garden type AC extension cords for portable radials with vertical antenna work. 

Attaching 3 or more AC pigtail sockets at the base of the antenna makes hookup easy enough and that configuration cannot result in a mistake where someone tries to feed 120 AC to the antenna since the Female side of the cords are the only open side. 

Foil sounds to be too much of a problem for reasons already mentioned in this thread. 
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N4NYY
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« Reply #4 on: September 26, 2010, 10:56:35 AM »

KE3WD,

Especially if you get wind like this :http://www.youtube.com/watch?v=PqmQ1CMrqkY
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K1CJS
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« Reply #5 on: September 26, 2010, 05:06:43 PM »

Foil is too easily torn, even though it will work pretty well.  One person trips or drags their feet, and your radials are history.  Better to get bright orange or yellow 14 gauge flexible wire (automotive wire works very well for this and is available in hundred foot rolls) and use it just for that.  Figure the amount you'll need for your radials and go to home depot or an electrical supplier and get the proper length cut.  You'll have it for years on end if you coil it neatly after using it.
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K3AN
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« Reply #6 on: September 26, 2010, 07:13:03 PM »

I'd only go with a vertical for FD if my site had no means of supporting some kind of dipole/doublet/G5RV, even at just 35 feet. FD is a domestic "contest" so you want high-angle radiation on 80 and 40. A vertical is also going to be noisier than a horizontally polarized antenna, and with June usually having lots of thunderstorms throughout the U.S., why punish your ears with extra QRN?
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KE3WD
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« Reply #7 on: September 27, 2010, 04:46:12 AM »

I'd only go with a vertical for FD if my site had no means of supporting some kind of dipole/doublet/G5RV, even at just 35 feet. FD is a domestic "contest" so you want high-angle radiation on 80 and 40. A vertical is also going to be noisier than a horizontally polarized antenna, and with June usually having lots of thunderstorms throughout the U.S., why punish your ears with extra QRN?


That's good advice. 

73
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WA3SKN
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« Reply #8 on: September 27, 2010, 11:19:50 AM »

You can use aluminum foil for radials.  Whether it is practical or not will be determined by the site location.  Field Day typically locates stations outdoors.  Do you have a site picked out yet, and what weather, wind, etc is expected?  I note the price is right.  Can you do an early setup to see how well it works... say several weeks or months in advance?  This can do wonders in your planning!

-Mike.
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KD8IWZ
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« Reply #9 on: September 27, 2010, 06:12:10 PM »

Mike, great suggestion on testing the site prior to Field Day, the site is on a knoll in the middle of a closely mown pasture, I'm introducing a new ham to the joy of FD. Will probably have a couple of burnt hot dogs and perhaps an adult beverage, just Elmering a good friend and showing him another side to our great hobby. And at our age, can't undertake too elaborate of an antenna farm, no trees close by to set up a dipole
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N4NYY
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« Reply #10 on: September 28, 2010, 08:23:22 AM »

Here is the problem with testing the day before. The weather might not be the same. And you have visitors, foot and vehicle traffic, etc. I am the Field Chairman for my radio club. I can only speak for myself and my club. Based on our location, being a 8A-9A, and amount of people involved, I would NOT allow this type of radial system. The problems outweigh the positives.

Also, someone had mention using a vertical on 40-80M and the noise associated with it. I can attest to that. I have a vertical at home, and get upwards of S9 noise at night. The dipoles and inverted Vs that we use was superior with that respect. The other thing is that a vertical on 80M will likely not cover the bandwidth of operaters.
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WA3SKN
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« Reply #11 on: September 29, 2010, 12:56:58 PM »

" the site is on a knoll in the middle of a closely mown pasture, I'm introducing a new ham to the joy of FD."

OK, you have your site picked out, and little foot traffic planned.
What times will you be operating?  This will determine the bands you will want to operate.  With sunspots as they are... 40, 20, and 15 meters come to mind.
With no trees or supports, it sounds like a ground mounted vertical may be in order.  Plan on radials or counterpoise of some sort.  I doubt the foil will work in pastureland, but a roll of wire from the hardware store will not cost too much.

So try a quick setup some afternoon in the next several weeks and see how well it works... it will be very educational.  The you can improve your plans and be ready for Field Day!
73s.

-Mike.
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N2EY
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« Reply #12 on: September 29, 2010, 03:10:59 PM »

As others have noted, the problem with using aluminum foil for that application is that it tears too easily.

Here's what I've done for Field Day verticals:

I built monoband 20 and 15 meter verticals from half-inch EMT conduit. The stuff is inexpensive and strong, and readily available. I elevated the base 5 feet by the use of PVC plumbing parts to make a base insulator, and a piece of galvanized with screws and wing nuts to hold the radial ends. The galvanized plate also held an SO-239 for the coax.

The antenna is assembled on the ground, hoisted up and secured by 3 radials of nylon or poly rope. The radials attach at about 2/3 of the way up.

The radials are #16 wire (because I had it) with pieces of plexiglas for insulators at the ends. The radials slope down from the feedpoint to the ground, raising the feedpoint impedance slightly and also acting as guy wires. I used 8 radials IIRC.

What bands do you intend to use on Field Day? How many hours do you intend to be on the air, and at what times of the day?

73 de Jim, N2EY
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KD8IWZ
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« Reply #13 on: September 29, 2010, 06:18:29 PM »

Mike & Jim, we plan to set up and be on the air at the start using a borrowed vertical for 40, 20, 15, and 10. Not sure how long these two seniors will stay up. It's sort of a "2 oldtime friends casual campout with Field Day thrown in" event. I do expect the xyls to check on us both days, doubt if we will see anyone else at the site. Basically introducing a friend and new ham to another part of the hobby. Based on everyone's suggestions, we will probably go with the wire radials, the foil was sort of a MacGyvir brainstorm. I really appreciate everyones responses, thats what makes the Elmer's forum so great. Hope to work all of you FD 2011 !

73   Dale
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N2EY
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« Reply #14 on: September 29, 2010, 06:38:47 PM »

OK. Here's what I'd do in that situation:

Get the vertical and a piece of masting long enough to put the base of the vertical at about shoulder level. This makes it easier to work on and improves the ground-loss situation.

Then make up as many radials as you can get wire for, and put the thing up as described earlier. 4 radials per band minimum, more is better. They don't have to be heavy-gauge wire.

One source of wire is an old microwave-oven transformer. Lots of enameled wire in the windings. Use the primary wire for the longer radials and the secondary wire for the shorter ones.

Guying is easier than trying to make a solid base to hold the vertical. Getting the radials up off the ground reduces losses somewhat and raises the radiation resistance.

If it is at all possible, you want to assemble, test and adjust the whole antenna *before* Field Day. There's enough work to do that day!

It is a very good idea to get out to the site as early as possible and get set up before it gets hot. On the bands you will have, the best action will be from the start until the sun goes down. After dark the upper bands start to fade out and 80 and 40 really come into their own, but you won't have an antenna for 80 and probably don't want to do the boiled-owl thing anyway.

What will you use for power? Shelter? Table?

What modes will you use? Remember that CW and digital get double points.

Go for the easy bonus points, too. Natural power, W1AW bulletin, SM message are just a few you can pick up on.

73 de Jim, N2EY (haven't missed a Field Day since 1968)


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