Topband: Tophat? Does it have to be at the top?

[N2TK]

How does the "hat" on a Cushcraft 402-CD work? You have those crossed
aluminum rods after the coil, then extended aluminum after that. What
happens if you take off the crossed rods?
73,
N2TK, Tony
-----Original Message-----
From: topband-bounces at contesting.com
[mailto:topband-bounces at contesting.com]On Behalf Of Thomas Kuehl
Sent: Sunday, June 06, 2004 1:59 PM
To: Bill; topband at contesting.com
Subject: Re: Topband: Tophat? Does it have to be at the top?

Bill,

The capacity hat should only be placed at the top of the vertical element.
Placing the hat any lower on the element essentially chokes off any current
flow above the hat making the antenna electrically shorter. The amount of
choking will depend on the capacitance of the hat.

Force 12 successfully uses small "hats" that act as traps in some of their
multiband antenna designs. There was a 20/15/10 meter design a few years
back that used this technique. They now employ the same concept in the
144/440 Ruby II, VHF/UHF antenna.

'73, Thomas - AC7A - Tucson

----- Original Message -----
From: "Bill" <k2wh at optonline.net>
To: <topband at contesting.com>
Sent: Saturday, June 05, 2004 2:39 AM
Subject: Topband: Tophat? Does it have to be at the top?


> I would like to operate 160m using a shortened vertical.  I have read
> alot about "Tophats" and
> I know what they do and why but, have never had an opportunity to put
> what I learned about them
> into practice.  Now I would like to.
>
> My question is:  Does a tophat always have to be at the top?  Or could
> it be a "Collar", half way
> up the vertical and maybe called a "Scarf"?
>
> K2WH
>
>
>
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> Topband at contesting.com
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