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Re: [TowerTalk] step away from stepIR

To: "David Gilbert" <xdavid@cis-broadband.com>
Subject: Re: [TowerTalk] step away from stepIR
From: "Rick Karlquist" <richard@karlquist.com>
Reply-to: richard@karlquist.com
Date: Tue, 12 Jun 2007 13:19:56 -0700 (PDT)
List-post: <mailto:towertalk@contesting.com>
David Gilbert wrote:
> Rob Atkinson, K5UJ wrote:
>
> "Is the element length for 50 ohm Z always the length for best
> performance?"
>

If you read the SteppIR docs you will quickly see that the
element drive impedance is not 50 ohms but 22 ohms.  There
is a transformer/balun to get back to 50 ohm coax.  A driven
element impedance of 22 ohms is quite reasonable in general
for Yagi design.  The impedance is not the tail wagging the
dog of the rest of the antenna design here.  That would be
the case if they tried to get 50 ohms driven element impedance
to eliminate the transformer.


Rick N6RK

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