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--
Guy L. Olinger
Apex, NC, USA
k2av@qsl.net
'AV since '74, previously K4VDL, K3FKJ, W2HVA.
(Remember those? Get in touch!)
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Message-ID: <3547C2D2.2EC9@qsl.net>
To: <towertalk@contesting.com>
Date: Wed, 29 Apr 1998 20:16:18 -0400
From: "Guy L. Olinger" <k2av@qsl.net>
Reply-To: k2av@qsl.net
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To: "L. B. Cebik" <cebik@utkux.utcc.utk.edu>
Subject: Re: [TowerTalk] C-3 & TH7 comparison - a revision
References: <Pine.GSO.3.96.980429171718.17896B-100000@larry>
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L. B. Cebik wrote:
>
> >
> > No, hams are not crazy. Stacking antennas at HF is really done
> > not to get the 2 or so db of stacking gain it is to get
> > a better take off angle pattern - it is this change in pattern
> > that accounts for the 10 db changes in signals when switching
> > between the stacked antennas.
>
> If all someone needs is a better take-off angle, that is, lower, then a
> stack is detrimental, since the antenna pair actually raise the TO angle
> relative to the TO angle of the upper antenna alone. However, the gain
> does not hurt a bit and gives the operator a variety of TO angles using
> the top only, the bottom only, and the pair together. In variety, there
> is success--but at the cost of erecting and maintaining the stack.
>
> Although 2 dB is only 1/3 of an S-unit, in the margins or in the piles, it
> can make the difference between being one of many or THE one heard.
>
It's not so much the lowest angle possible. It's to hit the angle of the
moment dead-on and not be transmitting or receiving on an antenna or
stack that has a null to the angle of the moment. *That* is worth many
more db than 2.
As to 2 db, I was taught in the old days that a 3db *difference* was the
smallest difference discernible by the human ear. That came from some
ne'er-do-well outfit called Bell Labs.
As to why big antennas and stacks, if one is QRO, it's hearing a weak
signal just barely made audible by that extra 2db, that Eu running 2/3
watt to a 20 foot noodle soaked in chicken soup, that the other
competition can't hear because he *doesn't* have the 2 db. It's the 2db
that just barely works the band in a weak opening that noone else knows
about. It happens. I've used those huge antennas.
73
--
Guy L. Olinger
Apex, NC, USA
k2av@qsl.net
'AV since '74, previously K4VDL, K3FKJ, W2HVA.
(Remember those? Get in touch!)
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