Very short 80m antenna

[Vic Rosenthal]

Today I am limited to the bands from 7 MHz and up and I want to get on
80m. My space is very limited, and in particular (due to the need to
rotate my existing dipole), there is no way to put up a vertical more
than about 3m high, and no room for radials longer than a few meters.

But the location is 35m above the ground and it is possible to add
another rotatable horizontal dipole to my mast.

So I am thinking about a 6m long dipole made of aluminum tubing. I have
some that is about 20mm in diameter. I will make capacity hats for each
side to add some end loading.

Yes, I know the bandwidth would be very narrow. But I could live with a
3:1 SWR bandwidth of 30 kHz.


I'm thinking about two possible configurations for loading coils: one
coil in the middle, or two coils, each about halfway down each side of
the dipole.

I know that two coils would produce a more efficient antenna. But the
one coil in the middle has two big advantages: it would allow me to feed
the antenna via an isolated link, which would solve the common-mode
problem without requiring a balun, and it would allow for easy tuning
and matching.

So what do you antenna experts think? One or two coils? Or is it just
crazy to expect anything from such a short antenna?
--
73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
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[Hajo Dezelski]

Hi,
everything is possible: https://www.qrz.com/db/K2MIJ

73 de Hajo
Gruss
Hajo

---
Cela est bien dit, mais il faut cultiver notre jardin.

http://hajos-kontrapunkte.blogspot.de/


On Sun, Jan 22, 2017 at 2:03 PM, James Rodenkirch
<[hidden email]> wrote:

> Don't give up on the notion of a shortened vertical just yet, Vic.
>
> Peruse this site and see if there is anything  that can help - http://www.arising.com.au/people/holland/ralph/shortvert.htm
>
> 72 de Jim Rodenkirch K9JWV
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[Jim Brown-10]

On Sun,1/22/2017 4:34 AM, Vic Rosenthal 4X6GP wrote:
> there is no way to put up a vertical more than about 3m high, and no
> room for radials longer than a few meters.

Hi Vic,

Can you bond to the structure of your building near the base of a
vertical?  If so, it will serve as a very effective counterpoise. Then
your 6m vertical with loading has a pretty good chance of working fairly
well.

73, Jim K9YC


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