Can't help with the modeling question but I have a Mosley tribander mounted
about 18 feet above a metal roof. On 20 meters, the roof has "some" effect but
not a lot. My lowest SWR is a little bit higher than I would have wanted
maybe 1.5:1. Mosley warned me the roof might couple with the antenna and pull
the lowest SWR point lower in frequency. That didn't happen to me but it looks
like what you are experiencing. You didn't say what the lowest SWR was. Is
the SWR low enough that you can just shorten the antenna to bring the dip up
where you want it?
If you are not being heard, I suspect there is something else going on. Are
you sure you don't have any issues with the coax, the feed, a balun, or
feed-line radiation distorting the pattern?
Radio k4ia
Craig "Buck"
Fredericksburg, Virginia USA
FISTS 6702 CC 788 Diamond 64
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|