NON-Conductive 'Pole' mounted atop CONductive pole (Galvanized Pipe and PVP Pipe)
Good Day All and a Happy New Year to All as well!
I realize this has previously been asked in one from or another - but, for clarity in my aging-mind I am asking again to be certain I have a firm grasp on wire antennas and how they are altered by nearby "metal objects" such as support poles/masts.
In limited space, I find myself erecting an Inverted-V. LOT SIZE is approximately 90 x 90 feet and comprised of "Southwestern Desert Sand" with a few feet of "dirt" from lord knows where; it is solid on top and no so below.
I can easily erect a "push up pole (mast)" near the center of the yard. Placing the "mast" in a piece of galvanized pipe sunk into the ground about five-feet for stability. This also shortens the "mast" five feet and make access a bit easier when the "push up" moment arrives. I believe I can safely elevate to 25 feet with the "push up mast" and then atop this attach a TEN FOOT section of NON-CONDUCTING "mast" to get the apex at roughly 35 feet. Guying utilizing a NON-conducting "rope" will also be part of the install.
The same HEIGHT cannot be obtained for the LATERALLY PLACED supports for the terminated ends of the Dipole / Windom or whichever antenna design I wind up purchasing. What I can do, however, is erect these lateral supports at height of 25 FEET -- the first FIFTEEN FEET being galvanized pipe (in the ground five-feet as with the center support) and the TOP TEN-FEET being a NON-conductive "mast" as used in the center support of the "V".
While I CAN place a 68 foot long antenna in various configurations and not be confronted with any "droop" of the ends - IF I use an OCF style antenna (Windom) it is possible from what I see in calculating "mast placement" that the "long leg" may be in close proximity to the "galvanized mast" at all three attach points.
MY QUESTION ("FINALLY"! they exclaim): Will the "conducting mast" at the apex of the "V" and at the termination of the "ends" of each "leg" create an issue with ANY antenna which may by design be erected in an "inverted-V" configuration? The upper-most portion of the support being the ten-foot length of NON-conducting 'pole/mast'. IF the long 'leg' should happen to "droop" to within a few feet of the conducting "mast" - is this a potential issue?
My previous QTH allowed me the benefit of a beam antenna but no 'wire antennas', thus this is my first attempt at erecting this type of antenna. I may be creating more issues in my mind than I will see in reality - but, to be sure I am, "just askin'!"
THANKS IN ADVANCE TO ONE AND ALL!
A conductive mast at the center or at the ends of your OCF should be less of a problem than the coax line to the antenna. You should have a choke on that but the shield is still there. You won't be able to remove all the common mode currents from the feedline because of the unsymmetrical nature of the OCF, but maybe you can get them down to insignificant - maybe. I can't say the mast will not pick up significant current. That depends on their length and their termination to ground. Feedline and masts should be at right angles to the antenna to minimize currents. Most people never see a problem because of mast currents even when they are present, although it is possible to alter the antenna pattern and gain by a small amount. I wouldn't recommend the use of a 10 ft length of PVC for an antenna support.
I wouldn't put a galvanized pipe into the soil. A piece of EMT tubing in the ground will last about 6 months at my house before it rusts thru and collapses. The best way is to put a 4x4 pressured treated post in the ground with a little concrete around the base and mount the pipe to that.
No, it won't, that is cause you a problem.