On Sep 15, 2008, at 12:16 PM, Rudy Severns wrote:
> Some multiband commercial verticals will work without a ground system.
> During my experiments earlier this year I tried an R7000 first with
> a large
> ground system and then removed the ground system. I could barely
> tell the
> difference. This check was done on 40m. Didn't see if this held
> for the
> higher bands but I suspect it would.
>
> The signal from the R7000 was a couple of dB lower than a full 1/4-
> wave with
> the same ground system. I suspect that was mostly due to loading
> inefficiency which is to be expected in short loaded antennas.
I have an R7000 mounted only 8 feet high. A couple of years ago, I
added eight 12 foot radials from the base of the support mast across
the ground. I found that this improved the reception of the antenna
markedly.
This antenna was designed to be mounted about 18 or more feet off the
ground. I think the radials help by reducing the ground losses that
occur from it being so close to the ground.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|