| Author |
Message |
    
Philuk
Junior Member
Username: Philuk
Post Number: 11
Registered: 4-2009
| | Posted on Tuesday, March 23, 2010 - 11:04 am: | 
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Hi, looking to erect an end fed wire for 40 to 11mts and have been looking at the possible placements outside, I could have it either inverted V or have the top end horizontal at about 40 to 50ft high as an inverted L shape, would the inverted L shape be better? as I would think this would give me both horizontal and vertical polarization. Any sugestions please.
regards
Phil. |
Starface
Senior Member
Username: Starface
Post Number: 2764
Registered: 1-2005
| | Posted on Tuesday, March 23, 2010 - 12:57 pm: |
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Try a G5RV , you can put them up either way you like and see what works best for you.
Everyone is trying to accomplish something big,
not realizing life is made up of little things.
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Tech237
Moderator
Username: Tech237
Post Number: 1321
Registered: 4-2004
| | Posted on Wednesday, March 24, 2010 - 11:39 am: |
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Both variations work, and with one works better depends on your location.
In the past I have used a G5rv in both variations in some places it worked better as an invert v, and in others as the inverted L. Try both and make your own determination based on your situation and needs.
Tech237
N7AUS
God only made some many perfect head, on the rest he put hair.
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Tech833
Intermediate Member
Username: Tech833
Post Number: 149
Registered: 12-2001
| | Posted on Thursday, March 25, 2010 - 12:53 am: |
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An inverted L will usually work much better than an inverted V, if you have some ground radials under it. But, if you don't have the ability to put any radials under your antenna, go with a center fed inverted V.
Your radio 'Mythbuster' since 1998
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Philuk
Junior Member
Username: Philuk
Post Number: 12
Registered: 4-2009
| | Posted on Thursday, March 25, 2010 - 7:21 am: |
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Due to my restrictions (area of outstanding beauty) once its up its staying up, I am way up in the hills in Northumberland UK, I get great North, East and West RX/TX but a steep hill rise behind me blocks the South, I have been alowed a vertical A-99 mounted 9ft from ground on a wooden fence poll screwed to the decking fence but thats my limit for visible antennas. I intend to use a few very high trees next to me 40ft apart that I could launch a wire into one early morning but wont be able to mess on with it for too long and attract unwanted interest. Have decided on an end fed tunable (qrp 100w max wire with a small variable cap. and 9:1 unun boxed/potted and weather sealed so I can physicaly tune to other bands when required for use with my QRP FT-817D without an indoor atu unit (also have indoor restrictions from the XYL)
If I get this wire to the top of one (inverted V) or two (inverted L) of the trees I should have great 360 degrees coverage, but only if I get the wire set up right for both vertical and horizontal polarization? hence ask first so its right the first time hopefully. No chance of any radials (not required for the end fed just short counterpoise) but a ground spike is in place near the base of the nearest tree, the ground below is always wet like all the ground here in Northumberland UK.
Looked at the G5RV but it is far too visible for my situation and centre fed means a highly visible coax run.
Hope this helps you guys understand the situation.
Phil. |
Tech833
Intermediate Member
Username: Tech833
Post Number: 151
Registered: 12-2001
| | Posted on Thursday, March 25, 2010 - 11:06 am: |
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Hi Phil.
Yes, that helps a lot!
Your end fed wire idea sounds like the best bet. However, you need to be aware that an end fed wire needs to work against a good ground radial system to work well. A single ground rod won't come close to being enough. A large metal roof (grounded) or some radials at the feedpoint are a must.
Suggest painting your A99 to help camouflage it. You could also paint a wire run to a tree. Or, use a very small wire that is nearly invisible. Small stranded stainless downrigger cable works great!
Your radio 'Mythbuster' since 1998
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Philuk
Junior Member
Username: Philuk
Post Number: 13
Registered: 4-2009
| | Posted on Thursday, March 25, 2010 - 1:21 pm: |
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@ Tech833 Thanks for that I live in a 30ft x 12ft static caravan (called a trailer in the US I think) this has a zinc roof would this do as a large ground area?
Phil |
Philuk
Junior Member
Username: Philuk
Post Number: 14
Registered: 4-2009
| | Posted on Thursday, March 25, 2010 - 7:20 pm: |
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Just had another look at the end fed wire plans I am following and the author Steve Yates AA5TB states no need for GPs just a short counterpoise? these plans can be found by a google search for (The End Fed Half Wave Antenna) by the above Mr S Yates, very interesting investigation into these end fed half wave wire antennas. Pitty I havnt got it ready as there is thick fog to cover my feindish plans HiHi.
Phil. |
Tech833
Intermediate Member
Username: Tech833
Post Number: 154
Registered: 12-2001
| | Posted on Friday, March 26, 2010 - 12:54 am: |
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A tuned end fed half wave does not need a ground plane for low SWR. And, it doesn't even need a ground plane to work well, in some cases. HOWEVER... In a sloper arrangement with the feedpoint less than 1/2 wave above ground (as in your case), without a good ground plane to work against, most of your RF won't go outward, but upward and into the ground and wasted as heat.
Yes, a metal trailer would make a good ground plane.
In your first post, you mentioned an end fed wire for 40 thru 11 meters. That is not a tuned half wave. Any non-tuned type end fed wire antenna will need a ground plane to work well. You may get a low SWR without a good ground plane, but most of your signal will be wasted.
Your radio 'Mythbuster' since 1998
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Mikefromms
Senior Member
Username: Mikefromms
Post Number: 1026
Registered: 6-2003
| | Posted on Monday, August 09, 2010 - 11:28 am: |
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Philuk, I'm having good luck with Yaesu FC-40 auto tuner for end fed wire. I can tune 80 thru 6 meters and it works. I'm in a similar situation and I think I'm going to make more use of the fence and bushes behind my house. Par electronics sells end fed antennas for 40 thru 10. Might be worth reading up on them. They have a perfect rating on ham reviews qrz. What I'd like to do eventually is get a version of the Astroplane (see the antenna reviews section here for antennas under 30') and paint it green or black and fit it into the background of the fence in the bushes. That, I know, would be my best bet for 10 and 11 meters. That thing should tune up 12, 15, 17 and maybe, just maybe 20, but that might be stretching it.
I've had a lot of fun building this and that to hide my hobby. My next project is a double extended zep dipole for 11 meters. I'm going to run it as a sloper with the main direction of interest being North since I'm in the south. Of course the thing will still receive the other directions. I have a .64 wavelength dipole up as a sloper right now for 11 meters. It is only 6 feet off the ground in the center. That's right. it works but not as good as I'd like. I've got to get a little more height. But you know what...I might do that Astroplane thing later on. I had one a few years ago and it didn't take long to regret selling it. Why did I sell it? Go figure...I didn't improve my situation really at all.
Mikefromms |
