Well, Carl
You just proposed a total height of 3/4 wavelength, it seems. Do you have
that much height?
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of ZR
Sent: Friday, September 06, 2013 9:26 AM
To: Shoppa, Tim; topband@contesting.com
Subject: Re: Topband: Are stacked verticals feasible?
Look at it as 2 ground planes with the lower feed point 1/4 wave above
ground along with its elevated radials which should make it pretty much
ground independent according to what has been published on here and
elsewhere.
The second ground plane would be identical with 1/4 wave spacing from the
top of the lower antenna or a 1/2 wave between feed points.
Then I would think that the ground conductivity at the reflection point
would be the only concern as far as efficiency and gain??
If installed as vertical dipoles then there would also have to be additional
spacing between them.
I would think that at 6-12' spacing from the tower it would minimize
interaction on 160 or 80?
Does anyone on here have EZNEC and can plot this?
Carl
KM1H
----- Original Message -----
From: "Shoppa, Tim" <tshoppa@wmata.com>
To: "Carl" <km1h@jeremy.mv.com>; <topband@contesting.com>
Sent: Thursday, September 05, 2013 10:30 PM
Subject: Re: Topband: Are stacked verticals feasible?
> Isn't this a "Vertical dipole"? Two quarter wave radiating elements? And
tower behind it will be some kind of reflector/director depending on height.
The radials seem unimportant if thought of this way.
>
> Tim N3QE
> ________________________________________
> From: Topband [topband-bounces@contesting.com] on behalf of Carl
[km1h@jeremy.mv.com]
> Sent: Thursday, September 05, 2013 9:17 AM
> To: topband
> Subject: Topband: Are stacked verticals feasible?
>
> Assuming that sufficient tower height was available, guy wires are
insulated
> or broken up into short non-resonant sections. Tower face is 12 or 18".
>
> Start at 1/4 wave up with a 1/4 wave ground plane with radials sloping at
> about 45 degrees. The vertical wire is 6-12' away from the tower face.
>
> Then a 1/4 wave (or 1/8) up install a duplicate.
>
> What does EZNEC say about this?
>
> With the different spacings?
>
> Effect of starting lower and how low before there are ground related
> problems?
>
> Phasing with coax or a LC network?
>
> Switching in a delay line to tilt the lobe up a bit?
>
> Curiosity got the cat!
>
> Carl
> KM1H
>
>
>
>
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