Depending on how big that metal roof is, I'd be more concerned with losing
antenna gain than with SWR...if the roof's big enough, it will become your
"earth" and send a lot of signal up at a higher angle than you'd like,
reducing gain at the horizon. -WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: K4IA@aol.com [SMTP:K4IA@aol.com]
> Sent: Wednesday, September 24, 2003 8:41 AM
> To: corneliuspaul@gmx.net
> Cc: towertalk@contesting.com
> Subject: [BULK] - [TowerTalk] sheet metal roof
>
> 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
_______________________________________________
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
|