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Conduit dipole swr issues

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  #9  
Old 01-25-2009, 05:13 PM
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Depends how heavy it is - of course. A solid piece of plastic or hardwood - like maple - would be ideal. You may want to consider what the effects of rain water would do, as far as seepage and drainage are concerned.
Do you have any pictures you can post - that would help a lot.
Let's see what you got going there.
Just a couple of thoughts.
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  #10  
Old 01-25-2009, 05:33 PM
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I'll try to get them up tomorrow if i get home early enough

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Old 01-25-2009, 06:10 PM
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1 more question the dowel I used is wood is there some thing stronger to use
Use fiberglass if you want it stronger and more weather resistant. You can get fiberglass rods in various diameters from here: MAX-GAIN SYSTEMS, INC.

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Old 01-25-2009, 07:16 PM
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Thank you I will deffinatly be ordering from them

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Old 01-26-2009, 06:31 PM
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Well the weather here isnt cooperating with me to get a pic just wondering would copper be a better material to make this antenna out of just trying to figure out the best way to make this. I really like making my own antennas and would like to try and make more. I wouldn't even mind trying to take a crack at making a mobile antenna.

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Old 01-27-2009, 04:25 AM
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Quote:
Originally Posted by ron103067 View Post
Ok I think I figured it out my antenna is way to long I never took into consideration the coax. Also the connection is 11 foot off the ground it is vertical and the coax is at a ninety degree to the antenna I have the bottom of the antenna 2 1/2 foot off the ground. I have it mounted to a tree trunk could this cause reflection. the tree is only on the ground side of the antenna. Plus about three feet from a shed. Just looking I lke building my own antennas and want to learn to do it right
Ron, all vertical antennas are adversly affected by the earth and it can really be significant if the voltage end of the antenna is close to just about anything. Much power to a vertical dipole only 2-3 feet above the earth will show heavy losses as heat in the soil. Horizontal polarization is much better in this regard, but it too likes to work high above the soil. The fact that the top of the dipole is above the tree top is of little importance, the bottom is the issue and it may show as much current flowing as does the top. The height and vertical polarization you mention are not serving you well. Your dipole will work, but you may not compare well with other stations nearby and other vertical antennas manufactured for CB that are mounted well in the clear.

You need the bottom to be maybe 10'-20' high for minimal results with a vertical dipole and that makes all the other requirements for location more difficult. A center fed dipole needs the feedline to exit the antenna perpendicular to the plane of the antenna for some considerable distance in order to avoid the worst kind of pattern distortions and that is straight up. Of course the tree and the shed are effecting you pattern in the worst way. If you have to work your vertical near the ground at your location, it is even more important that you be in the clear for at least a wavelength or more in all other directions.

It appears to me that you may be doing you antenna building and comparison work in the worst conditions possible.

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Old 01-27-2009, 06:29 AM
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Originally Posted by Marconi View Post
Ron, all vertical antennas are adversly affected by the earth and it can really be significant if the voltage end of the antenna is close to just about anything. Much power to a vertical dipole only 2-3 feet above the earth will show heavy losses as heat in the soil. Horizontal polarization is much better in this regard, but it too likes to work high above the soil. The fact that the top of the dipole is above the tree top is of little importance, the bottom is the issue and it may show as much current flowing as does the top. The height and vertical polarization you mention are not serving you well. Your dipole will work, but you may not compare well with other stations nearby and other vertical antennas manufactured for CB that are mounted well in the clear.

You need the bottom to be maybe 10'-20' high for minimal results with a vertical dipole and that makes all the other requirements for location more difficult. A center fed dipole needs the feedline to exit the antenna perpendicular to the plane of the antenna for some considerable distance in order to avoid the worst kind of pattern distortions and that is straight up. Of course the tree and the shed are effecting you pattern in the worst way. If you have to work your vertical near the ground at your location, it is even more important that you be in the clear for at least a wavelength or more in all other directions.

It appears to me that you may be doing you antenna building and comparison work in the worst conditions possible.
I will have to move the antenna. I'm just right now testing the swr and trying to see if I have done a good job. I'm always trying to figure out where I can put this antenna. I've got a lot of trees and stuff around, my hope is that this tree I'm using is just a trunk that is approximatley 10 foot tall and want to attach antenna to the top which is higher than the shed. I'm just worried cause the wood dowel I use is a hardwood but it breaks easily. So I'm trying to get something I can use to connect the two sections that is strong enough to handle the weight

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  #16  
Old 01-27-2009, 07:12 AM
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Just for grins, try it the other way around. Instead of sticking something inside that conduit, try sticking that conduit into something. As in a chunk of wood maybe 3" x 3" and long enough to provide a surface to mount the thing with. Bottom conduit won't stay in that block? Use a screw/bolt through the block and conduit to hold it in (also provides a nice place to make electrical contact). Do the same thing for the top conduit, what'tha'heck? Or, substitute plastic/fiberglass/ceramic/whatever for 'wood'. All kinds of options there. Sort'a the same thing commercial builders do with antennas, just not as 'sophisticated'?
- 'Doc

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