On Thu, 19 Mar 1998 10:23:14 -0700 Eric Gustafson Courtesy Account
<n7cl@sparx.mmsi.com> writes:
>
>>From: km1h@juno.com (km1h @ juno.com)
To: <topband@contesting.com>
>>Date: Wed, 18 Mar 1998 10:25:31 EST
>>
>
>Snip...
>
>>Re..your other post and the April '98 QST comments by
>>N6BV... Does not the military use NEC-4xx to model their field
>>installed and stealth antennas? The question remains; are those
>>models accurate to within < 1dB?
>>
>
>In a lot of cases they can be. Just as other modeling based on
>previous versions of the NEC code can be. In this specific case
>of correctly accounting for all of the system losses of a
>vertical with a radial field of varying density under it, at
>varying distances in close proximity to earth, apparently not. I
>say this because they report results that do not agree with
>measurements taken at various times spanning many years in
>various locations by various researchers.
But you said earlier that you have no experience with NEC-4...?? That was
the ONLY program I asked about.
>
>By the way... I personally use several of the modeling programs
>both for my hobby and at work. I find them to be extremely
>useful. I find them to be even more useful if you understand
>their limitations (which I don't pretend to do completely), and
>can devise model adjustments and/or compensations to mitigate the
>effects of the limitations. But from MININEC right on up, I have
>found that in general, unless you have a pathological model
>construction, they get the pattern SHAPE very nearly exactly
>correct when fed the correct constants for conductor and ground
>losses.
>
>I'm not running down the modeling programs at all.
I thank you for this but another constantly does run them down but with
no real paper to back it up. This is where the confusion starts for me.
On the one hand this individual condemns a lot of stuff as "hamlore" but
possibly generates as much more on his own....and is unpublished as far
as I know ( Outside of one joint effort with acknowledged experts). I
thought peer review was paramount?
I just
>recognize that for this particular case, in my experience, they
>do not completely agree with reality. They still permit me to
>gain vastly more insight into the antenna systems than I could
>without the models to play with.
>
I have absolutely no argument with you that some modeling programs have
serious flaws....BUT they are known, published and compensated for by the
serious users.
I hope that I can get some "real" suggestions here to improve my system
...before fishing season starts.
73 Carl KM1H
>73, Eric N7CL
>
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