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Re: [TowerTalk] SteppIR

To: towertalk@contesting.com
Subject: Re: [TowerTalk] SteppIR
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Fri, 27 Feb 2015 16:48:26 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

On 2015-02-27 3:10 PM, john@kk9a.com wrote:
To some degree this is true but I am not sure that you can have optimum
spacing for that big of a frequency range and still maintain a constant
impedance.

There are several antenna designers who have shown that the impedance
a simple driven element is in the mid-20 Ohm range when the antenna is
tuned for maximum gain (assuming the boom is not too long for the number
of elements).  That changes when extra/coupled elements are used (e.g.
OWA).  SteppIR's antennas are all 23 Ohm designs with a 2.25:1 "balun".

> It would be nice to see a model.

Dig out any yagi optimizer, plug in the SteppIR element positions and
have it optimize for maximum gain with the fixed positions.  You will
get a series of element lengths and performance that very closely
tracks the SteppIR specs (been there, did the exercise 10+ years ago).

73,

    ... Joe, W4TV
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