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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 10:27:18 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

> My question: With a SteppIR beam, what is the tradeoff of the fixed
> element spacing on gain and pattern?  Especially compared to the
> multi-yagis-on-one-boom high end multiband antennas.

There is no trade-off in gain.  Gain is almost entirely a function of
boom length as long as you don't have to few elements.   For example,
SteppIR antennas all show more gain on 10/12 meters than the multi-
monoband yagis simply because the SteppIR antennas utilize the entire
boom length on all bands where the multi-monoband antennas typically
use 60-70% of the available boom length on each band.

Where the boom is "short" and the spacing is narrow, you give up
bandwidth but SteppIR compensates by retuning.

When the boom is "long" and the spacing is wide you give up some F/B.
For example, the 3 element SteppIR shows F/B of "only" 15 dB on 12
meters and 11 dB on 10 meters vs. 25 dB on 20 and 17 meters.  You see
similar F/B declines with the 4 element antenna.

With SteppIR the trade off is increased complexity (the stepper
motors and brush contacts) while with the typical overlaid multi-
monoband antenna the trade off is decreased gain for a given boom
length.  All of this is verifiable with a few hours spent using a
good antenna modelling program.

73,

  ... Joe, W4TV


On 2015-02-27 9:51 AM, Al Kozakiewicz wrote:
I was tempted to hijack the Mosley thread, but it should probably be allowed to 
die peacefully.

I discovered a few years ago that you can't ask any questions where an honest 
answer might be construed as a criticism on the SteppIR forums.  The dialog 
degenerates into something resembling the useless old alt.advocacy newsgroups.

My question: With a SteppIR beam, what is the tradeoff of the fixed element 
spacing on gain and pattern?  Especially compared to the 
multi-yagis-on-one-boom high end multiband antennas.  You're pretty much in the 
same territory price-wise.

Al
AB2ZY
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