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[Towertalk] Need Antenna Advice!

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Subject: [Towertalk] Need Antenna Advice!
From: (
Date: Sat, 14 Sep 2002 01:51:43 -0600
The SteppIR 3L Yagi has a 16 ft boom.

This corresponds to 0.46 WL on 10M,
                      0.34 WL on 15M,
                          0.23 WL on 20M.

The W2PV Yagi Design Book shows 
gain and F/B curves for 3L Yagi's with
boom lengths from 0.1 to 1.0+? WL
and parasitic element tunings offset
by 2,3,4,5,6,7 percent.

Bottom Line:  Boom lengths around 0.25 WL
(and odd multiples) exhibit HIGH F/B ratios
but lower gain (-1 dB), Boom Lengths around
0.5 WL exhibit LOW F/B ratios and high gain,
and boom lengths around 0.35 WL are a good
compromise between gain and F/B.

The SteppIR can be optimized for each band
given it's FIXED boomlength, but remember that
for full optimization ALL parameters (including 
Boomlength) must be varied.  This is NOT the
case with the SteppIR antenna.  On 20M, it's
F/B can be made to be near optimum.  On 15M,
it can achieve good gain and intermediate F/B,
on 10M it can achieve good gain but LOW F/B
as originally stated.

Tom  N4KG

On Fri, 13 Sep 2002 writes:
> In a message dated 9/13/02 11:07:48 AM Pacific Daylight Time, 
> writes:
> > You might consider how important F/B is to you...the TH11 is 
> excellent on
> >  all bands; the StepIR is good on 20m and degrades on the higher 
> bands..
>     I think it's the other way around. The StepIR is an optimized 3L 
> beam AT 
> Cheers,
> Steve   K7LXC
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