Has anyone ever taken one of these 43 foot verticals and done something
similar to the 38 Foot 80M Capacitively loaded wire vertical? Obviously
since you have the extra 5 feet, you wouldn't need as large of a capacity
hat, but it would have the added benefit of being resonant on 80M and
providing you with 2 guy wires at the top... You could probably almost
justify the cost of the thing just in that you'd get a killer antenna on
75/80 with just a very minor modification. (Adding a wire capacity hat
sloping downward.)
http://home.comcast.net/~kb0fhp/80M_Vertical/80M_Vertical.htm is the link to
the design I am talking about.
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
Sent: Tuesday, February 17, 2009 8:45 AM
To: Michael Ryan
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] 43' verticals
Michael Ryan wrote:
> One of the older ARRL Antenna Books had an interesting article some years
> about about a helically wound 160 vertical, wound around a 4" or 6" ( I
> think ) PVC pipe about 20ft or so high. Looked like a lot of fun but
never
> got 'around to it." - Mike
>
Helically loaded antennas have been around a long time, and keep popping
up (see, e.g. the Univ of Rhode Island guy)..
Unless you're using BIG wire, odds are, for the same physical size, your
losses will be lower with a separate matching network at the base and a
capacity hat. You'd have to run the numbers for yourself to figure out
where the trades are.
The "wire around a structure" thing works nicely for mobile antennas
(I'm using about 25 feet of AWG 16 wire wound around a standard 10m
mobile whip).. it provides enough extra inductance to make the job of
the autotuner at the base reasonable.
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