You must use a current type balun or coiled coax
at the feed point to prevent common mode radiation
on the outside of the feed line when using elevated radials.
The coax could become a radial if it is not laid under the
ground or on the ground until you get away from the antenna
base. Again, current baluns can be used to break up any
common mode radiation as the feed line progresses toward the TX.
Phil, K5PC
----- Original Message -----
From: alsopb <alsopb@gloryroad.net>
To: <towertalk@contesting.com>
Sent: Wednesday, October 13, 1999 12:06 PM
Subject: [TowerTalk] resonant coax braid effect on ants?
>
> Guys,
>
> There has been plenty of discussion on
> non-resonant guys and the desirability of having
> them non-resonant lengths.
>
> Now what about the outer braid of the coax you
> feed your antenna with?
> It's conductive, it is often run out from the
> tower some distance below the antenna. Can't it
> be "resonant" and re-radiate too? Why does this
> not seem to be a concern.
>
> Another thing:
>
> The RF you pump into your coax is supposed to
> reside on the center conductor and the INSIDE of
> the braid. How is this possible when all UHF
> connectors solder to the outside of the braid?
> Dumb question I know but it has been bugging me.
> I suppose I could go back to E&H field equations
> and get an answer....
>
> de Brian/K3KO
>
> --
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>
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