[TowerTalk] book Tribander comparison test

[jimlux]

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 at audiosystemsgroup.com>  wrote:
>