On 3/1/11 5:04 PM, Barry Kirkwood wrote:
> Are you telling us that yagi element spacing has no effect on front to back
> ratio?
Pretty much, at a single frequency, one can optimize for F/B and feed Z.
basically, you have 3 variables you can play with on a SteppIR.. the
element lengths. You can pretty much find a combination of lengths that
will optimize any two parameters out of {Z, F/B, Directivity}
Where it gets sticky is if you want to optimize, say, Front/Rear (aka
average or peak sidelobes) or if the boom length is such that the
elements are too far apart.
In a fixed configuration Yagi-Uda, you're looking to simultaneously
optimize Z, Gain, and F/B, and that's hard to do over a frequency *range*.
If you've got Matlab or Octave, you can get some nifty stuff from
Sophocles Orfanidis's web site that lets you simulate and optimize this
kind of thing in an idealized sense. Or you can download 4nec2, and let
Arie's optimizer grind on it.
These days, computers are so fast, that you can run a dozen cases in 10
minutes. Sure, you can find pathological cases, but for the most part...
> If so, not correct.
> 73
> Barry ZL1DD
>
> On 2 March 2011 00:56, Jim Brown<jim@audiosystemsgroup.com> wrote:
>
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