Antenna Project  | | 
04-26-2009, 11:27 PM
| | Member | | Join Date: Mar 2009
Posts: 38
| |  Antenna Project
Well after a couple of weeks experimenting with an end fed wire antenna for 11 meters and trying to get the matching cicuit right (and fighting with my OCD  ) I have started the "final" design of my vertical ground plane antenna. Once I got the matching circuit right (photo 1), I ended going with an air wound coil and a coax capacitor which brought the SWR down to 1.5:1 on the wire antenna and I'm pretty confident I can get this setup to work with the vertical. I was able to pickup some aluminum tubing that is 7/8" in diameter and about 5' long. I joined them with a two foot wooden dowel and a coupler made from conduit and hose clamps (photos 2 & 3). The overall length is 22.5 feet and seems to be very strong and lightweight. Photo 4 is the completed radiator attached to the base and the enclosure for the matching cicuit. Photo 4 also shows the mount and support which is pressure treated 2x4's I had laying around which is designed to transfer the wind stress around the base and enclosure straight to the antenna mast which will be 1.25" conduit extending all the way to the ground from the roof peak. Photo 4 shows the antenna attached to my pool deck and is currently going through wind testing. So far so good, had a good windy one on Saturday and the only thing I had to change was the length of the radiator support, the weight of the antenna was pulling it over from upright.
More to come. Any suggestions welcome.
John |
04-26-2009, 11:38 PM
| | Member | | Join Date: Mar 2009
Posts: 38
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More pictures. |
04-26-2009, 11:45 PM
| | Member | | Join Date: Mar 2009
Posts: 38
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and more pictures.
Photo 1 is the original support (sagging bad)
Photo 2 is the extended support (much better)
Photo 3 is the ground radials. They are 6' aluminum tomato stakes which i ran 102" of 14ga copper wire down the length and it extends about 2' off the ends. |
04-27-2009, 03:51 AM
|  | Senior Member | | Join Date: Jan 2009 Location: Rogers, Ar
Posts: 208
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Very cool. It seems you've worked out the mechanics of it all. Looking forward to your results.
My 5/8 vertical has worked out well after trial and error. It is going to be up for a long time I think.
Tell us more. |
04-27-2009, 05:13 AM
| | Member | | Join Date: Mar 2009
Posts: 38
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Will keep you updated. I've been working on making it as beefy and lightweight as possible. Have not made any "electrical" connections yet, I am going to leave it up as is for a few days as we are supposed to get some wind and storms and want to see how it does. 
John |
04-27-2009, 06:09 AM
| | Supporting Member | | Join Date: Apr 2005 Location: Oklahoma
Posts: 3,036
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After what happened to the last one, a wind tunnel test doesn't seem completely unreasonable, huh? 
And I also think you will find that since it's so close (touching) that wooden support, the tuning/matching is going to be slightly different, and will change when things get wet. Probably not a large change but still a change, which is normal.
- 'Doc |
04-27-2009, 09:48 AM
| | Senior Member | | Join Date: Jan 2009 Location: Rogers, Ar
Posts: 208
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Quote:
Originally Posted by W5LZ  And I also think you will find that since it's so close (touching) that wooden support. . .
- 'Doc | What I had to do was to lengthen and double (one piece of PVC inside the other) the pipe coming out of the top of the 4"x1/2;4" adapter and use that for additional support.
See Five-Eights Wave Redo |
04-27-2009, 04:44 PM
| | Member | | Join Date: Mar 2009
Posts: 38
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Doc, I haven't had a failure yet but I did see what Homer's did and wanted to avoid that if at all possible. All the wood is going to painted with exterior paint, should I insulate the antenna from the support or will that make any difference? The support goes up the antenna about 3' so very little of the radiator if physically blocked by the support.
John |
04-27-2009, 06:39 PM
| | Supporting Member | | Join Date: Apr 2005 Location: Oklahoma
Posts: 3,036
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Oops! So I got the two of you confused. I'm real good at that sometimes! (Oh $#;+, now which one do I apologize to??)
I think painting that wood would be a good idea. Not because it'll change what happens with the antenna, but to keep it from the normal weathering process. How it will affect that antenna is because of it being 'close' so it won't change that part. Unless that paint is conductive, and don't bother asking, I have no idea.
- 'Doc
................
MEMO
From: Subconscious
To : 'Doc
Would you please pay attention! Look how you are embarrassing me. It ain't easy being you, you know. Don't make it any harder! |
04-27-2009, 07:58 PM
| | Supporting Member | | Join Date: Apr 2005 Location: Oklahoma
Posts: 3,036
| |
Just for grins, the attachment is from that 23rd edition with a little modification (added the colors). 'Blue' is for distance between antennas, 'red-ish' if for the phasing lines. It's NOT enough information to do the phasing correctly, just an example of 'wazinda' book.
- 'Doc | | |
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