160m Vertical Questionas
I have a 105' tower with a cluster of yagi's on top. There are various
fixed-direction yagi's bolted to it, along it's height. There are 17 runs of feedline that come from the tower to the shack. I've always wanted to install something vertical for 160m use in the quiet winter months. The 1st and 2nd layer of guy wires are un-insulated from ground/tower. The top guy wires are broken into full 40m sloping dipoles and are remotely switched. Due to all of the other rigs running at the same time and the amount of feedline entering the shack, I don't think I want to shunt feed the tower for fear of getting loads of RF in the shack (had a friend who tried this and was never able to fix the problem with RF in the shack). Here's my question: - Can I use insulative side-mount brackets and string a vertical up the side of the tower, seprated from the tower by a few feet, and get any kind of decent vertical antenna performance out of this? I was thinking of maybe 5' off the side of the tower, running a wire up to 105', then shoot the other 30 or so feet of wire off and fold it back down and outward at 45 degrees or so. Feed it at the bottom, and install a ground field aound the base of the tower. I realize there will be some coupling to the tower, but don't have any way (or know how) to model this. Can anyone help with a model to determine approximately how much I'll have to compensate wire length for couplng and top foldback? Have any of you done this before? Thanks, ave WB4IUY www.WB4IUY.net |
160m Vertical Questionas
On Oct 30, 11:50*am, Dave WB4IUY wrote:
I have a 105' tower with a cluster of yagi's on top. There are various fixed-direction yagi's bolted to it, along it's height. There are 17 runs of feedline that come from the tower to the shack. I've always wanted to install something vertical for 160m use in the quiet winter months. The 1st and 2nd layer of guy wires are un-insulated from ground/tower. The top guy wires are broken into full 40m sloping dipoles and are remotely switched. Due to all of the other rigs running at the same time and the amount of feedline entering the shack, I don't think I want to shunt feed the tower for fear of getting loads of RF in the shack (had a friend who tried this and was never able to fix the problem with RF in the shack). Here's my question: - Can I use insulative side-mount brackets and string a vertical up the side of the tower, seprated from the tower by a few feet, and get any kind of decent vertical antenna performance out of this? I was thinking of maybe 5' off the side of the tower, running a wire up to 105', then shoot the other 30 or so feet of wire off and fold it back down and outward at 45 degrees or so. Feed it at the bottom, and install a ground field aound the base of the tower. I realize there will be some coupling to the tower, but don't have any way (or know how) to model this. Can anyone help with a model to determine approximately how much I'll have to compensate wire length for couplng and top foldback? Have any of you done this before? Thanks, ave WB4IUYwww.WB4IUY.net a simpler method is to put an insulator at the top of the tower and run up at an angle so its 20' or so away from the tower at the ground. the further away from the base of the tower the less coupling and the more wire there will be going up... and the more art will like it! |
160m Vertical Questionas
On Oct 30, 6:50*am, Dave WB4IUY wrote:
I realize there will be some coupling to the tower, but don't have any way (or know how) to model this. EZNEC will do that. A quick look says that it will work just fine. There's not much difference in feeding the tower and feeding a wire parallel to the tower. -- 73, Cecil, w5dxp.com |
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