Here's another reason why someone might choose fixed elements, price.
I don't mean to disparage the SteppIR, it has a lot going for it, but consider
that the 4-el SteppIR is $1,745.
The C3E is $735, the C3S is $610.
If the added performance in Joe's chart below is worth $1,000 to you, then
by all means. The SteppIR will also outperform the F12s on frequencies
the F12 is, by F12's own admission, a compromise (WARC bands).
If the added performance and frequency agility is not worth $1,000, then
you may wish to stick with fixed-element designs.
73, kelly
ve4xt
> From: "Joe Subich, K4IK" <k4ik@subich.com>
> Date: 2005/03/17 Thu AM 10:47:03 CST
> To: "'Bill'" <w5vx@hiline.net>, <towertalk@contesting.com>
> Subject: Re: [TowerTalk] How can a SteppIR Perform So Well?
>
>
> W5VX writes;
>
> > I think the point I was trying to make was... if a well
> > designed yagi with 4 elements works as well as a well designed
> > 5, 6 ... element yagi, then why would anyone want to purchase,
> > buy, or build the larger antenna?
>
> The key is in what you mean by "performs as well." If the only
> concern is gain at a specific frequency, then the four element
> antenna will perform just as well as a five, six or more element
> antenna on a boom up to about 3/4 wavelength. If your concerns
> include SWR, F/R and bandwidth, the design flexibility provided
> by the additional fixed length elements will allow the antenna
> with the "extra" elements to outperform the four element design.
>
> However, if you remove the constraint of fixed length elements
> and bandwidth, the four element antenna again becomes a valid
> choice.
>
> SteppIR's unique asset is the adjustable (tunable) element.
>
> The three element SteppIR is a valid comparison to your C3 ...
> the SteppIR has half the elements on a boom that is two feet
> shorter. Yet the SteppIR outperforms the C3 in model studies
> and range tests using the K7LXC/N0AX protocols.
>
> > The SteppIR 3 element yagi vs Force 12 C-3E (74' above ground)
> >
> > C-3E SteppIR elev.
> > Band Gain F/R Gain F/R
> > 20 12.6 16 13.4 20 13 degrees
> > 17 10.3 7 13.8 21 10 degrees
> > 15 12.8 17 14.2 21 8 degrees
> > 12 9.8 9 14.8 14.5 7 degrees
> > 10 13.2 21 15.2 11 7 degrees
> > 6 n/a 16.0 20 4 degrees
> >
> > The C-3E numbers are Force-12 published specifications and
> > confirmed by modeling with AO. The SteppIR numbers are from
> > modeling in AO/YO (6 meter values use the optional passive
> > elements).
>
> 73,
>
> ... Joe, K4IK
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers",
"Wireless Weather Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|