As Steve suggested, BUY MORE Rohn 25.
Coupling into tapered sections is inefficient and produces little
added loading. It is best to maintain a constant diameter.
Or, USE TOP LOADING. Loading wires can easily be added and adjusted.
Keep them opposite each other to cancel any horizontal radiation.
A concrete pad is probably sufficient insulation with a low feedpoint
impedance. Use a baseplate on the bottom section. (Saves lotsa $$$).
(WA4CTA found a noticable change in feed impedance of his elevated GP
reverse fed antenna when he removed the ground wires from his concrete
pad mounted tower, and no change in impedance when it rained.)
de Tom - N4KG
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & KM9P
|