A classical parallel resonant trap can be made resonant and isolating at a
frequency but shows inductive reactance at lower ones.
You can isolate the top hat on 40 with a trap, but then you can't use such
trap in a resonant vertical unless shortening the antenna (in this case the
top hat).
One might think to add a -jX reactance over the trap, thus cancelling the
trap effect, but this will modifiy the original current distribution.
Not necessarily the new current distribution will be destructive with the
antenna performance and this could be an acceptable solution.
73,
Mauri I4JMY
----- Original Message -----
From: <K3BU@aol.com>
To: <towertalk@contesting.com>
Sent: Thursday, July 19, 2001 4:26 PM
Subject: Re: [TowerTalk] Top Hat Switch (mercury)
>
> In a message dated 7/19/01 9:49:36 AM Eastern Daylight Time,
w8ji@akorn.net
> writes:
>
> >
> > You may have missed it Tod, but two solutions were given and
> > rejected.
> >
>
>
> Maybe I missed something, but what about using simple trap? Trap isolates
or
> "disconnects" rest of the radiator above trap. They can be made efficient.
> The disadvantage is they are frequency specific, but for ham bands good
> enough.
>
> Yuri, K3BU
>
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