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[TowerTalk] High Antenna Modelling

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Subject: [TowerTalk] High Antenna Modelling
From: (Hisashi T Fujinaka)
Date: Sat, 2 Feb 2002 09:31:47 -0800 (PST)
While I trust the NEC-2 engine, it is still idealized and computer
simulations should not replace common sense. I say this with a lot of
experience modelling analog and digital ICs pre-layout. There are
conditions where the simulation just doesn't work out the way it really
turns out.

Common sense is sometimes hard to come by in ham radio, where peoples'
knowledge of science comes from an odd collection of study, anecdotes, and
hearsay. For this reason, it might be better to trust the simulation than
"ham sense." But don't think the simulation is the be-all and do-all.

On Sat, 2 Feb 2002, Pete Smith wrote:

> At 10:40 AM 2/2/02 -0500, N8DE wrote:
> >Pete,
> >Perhaps my use of the word 'excessive' wasn't quite correct for the
> >situation described, but the results of modelling are still IDEALIZED.
> >
> >You say you don't agree .. but then you talk about a 'smooth and
> >predictable change in the radiation pattern' ... this is IDEALIZED ..
> >
> >As I said:
> >
> >This is one of the reasons that we must NOT trust the software to give
> >EXACT answers, but rather to give 'idealized' situational results of the
> >MATHEMATICS involved [not shouting ... just emphasis].
> Again, I disagree.  For a flat, smooth foreground, the change in the real
> radiation pattern IS smooth and predictable.  Then you put the same antenna
> over an irregular foreground, and of course the resulting far field is no
> longer smooth or regular, but that's a whole 'nother topic, one which is
> every bit as difficult as modeling the antenna's field in the first place.
> But I repeat, good modeling aims to use mathematics to produce a good match
> to the observable world.  Unless it is close enough to real, it is
> essentially useless.  NEC-2 is far from useless.

Hisashi T Fujinaka -
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