[TowerTalk] 80 M 4 SQUARE MODELING
jimlux at earthlink.net
Fri Jul 21 15:19:57 EDT 2017
On 7/21/17 10:18 AM, Kenneth Goodwin wrote:
> Whether it works or doesn't work, what's your alternative? Biggest problem
> with antenna modeling software is that the software can't take into
> consideration the physical constraints without extensive sensitivity
There are tools now that let you do that kind of sensitivity analysis in
an automated way - since it doesn't take hours to run the NEC model for
And, from a sensitivity analysis standpoint, you can use a "reduced
complexity" model - you're interested in whether there are major
changes in VSWR or gain or null depth (mostly the latter) as things move
in the wind or relative to surroundings.
The surroundings can be modeled fairly simply for this kind of thing
(sure, if you have a really good model of your house and surrounding
trees, then load it in as numerical Green's function, but you probably
don't need that).
And if you move your baseline model by 6 inches, the whole thing
> changes and you don't have the means to control the physical parameters to
> that degree. Here is what you are supposed to have learned in numerical
> analysis, the optimum solution is not necessarily the best solution. Ken
Very much so.
Or another way - HF Yagi-Uda designs which have performance that falls
apart if the end of the element moves an inch are probably not "robust"
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