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Re: [TenTec] was OT: Indoor Antenna: re B&W type terminated dipoles

To: tentec@contesting.com
Subject: Re: [TenTec] was OT: Indoor Antenna: re B&W type terminated dipoles
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 07 Dec 2010 09:12:06 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>

On 12/7/2010 5:58 AM, Jim WA9YSD wrote:
> Any antenna for that matter looses 1/2 their power or more when operated on a
> band that it is not designed for.

Why do you say that? I don't agree. It may not radiate in the direction 
it did on the fundamental. The system may loose power from matching 
network losses when the impedance is obnoxious to match, and the really 
short antenna looses radiation efficiency.
> Efficiency for a folded dipole has a factor of around 0.98
> Efficiency for the common dipole is about 0.1

Nah, there's no reason the common dipole should be poorer than the 
folded dipole.

> Efficiency for the Double bazooka is about 0.89

Balderdash. The double bazooka is no better than a folded dipole and has 
no significantly greater bandwidth except what comes from the fatter 
radiator ends of shorted together twin lead. It suffers from having tiny 
conductors encased in insulation that make it structurally weak in wind 
and ice. If cross connected at the center instead of the original series 
connection, the two quarter wave coax stubs do compensate for reactance 
changes and give that variation a greater impedance bandwidth. But its 
still wimpy and breaks all the time in the real world.
> Efficiency for the above cases is its ability to couple.  So your use of the
> word efficiency must be defined better so it is not so confusing as to what
> exactly your talking about.
> Stay on course, fight a good fight, and keep the faith.  Jim K9TF/WA9YSD
> -----------------------------------------------------
73, Jerry, K0CQ
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