[TowerTalk] 4el SteppIR at Dayton?
n4zr at contesting.com
Tue May 20 12:46:27 EDT 2003
At 02:28 PM 5/20/03 -0700, W6TKV wrote:
>Most of what I think I know about Yagi design came from spending time
>with the K6STI's Yagi Optimizer design program. Clearly, any design is
>always a tug-of-war between front-to-back, forward gain and SWR. I
>realize the Steppir optimizes SWR vs. frequency, but I wonder what the
>design parameters are for front-to-back and forward gain.
>Has anyone thought much about this ... or asked?
Sure -- it's a little like the old NASA line: "faster, better, cheaper --
choose any two." If you can vary element length, but not spacing, then you
will sacrifice either gain or F/B, or maybe both, compared to an optimized
fixed yagi (depending on which band you are on). The same is true of
trapped tribanders, though some of them have extra single-band
elements. Arguably, if it will hold up mechanically, the SteppIR is a
better solution than any trapped tribander with compromise spacing, because
it adjusts within bands, where normal yagis must be optimized somewhere in
the band and not elsewhere.
A search of the Towertalk archive on contesting.com will turn up a useful
series of messages about this.
73, Pete N4ZR
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