[TowerTalk] resonant coax braid effect on ants?

Harv Shore af006@lafn.org
Wed, 13 Oct 1999 11:23:16 -0700


Interesting points indeed!

I recall a discussion with a guy who had a bunch of commercial antennas some
time ago.  He brought all the coax cables down to the base of the tower
where he attached a grounding bus to the shields.  I thought he was crazy
but he said he did it to reduce cross coupling from coax radiation.  I
pointed out that the antennas where in close proxin\mity and that they would
couple too!.  I never did get an answer -- could this be a way to insure
non-resonant coax feedlines?

The best "cheap" connectors we used to use were Kings crimp ons.  They made
contact to the inner surface of the braid.
I think the old GR loww SWR connectors also were made that way.
73
Harv
K6EXO

----- Original Message -----
From: alsopb <alsopb@gloryroad.net>
To: <towertalk@contesting.com>
Sent: Wednesday, October 13, 1999 10:06 AM
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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