hello Ed, Guy and Dave,
there seems to be some misunderstanding... as I see it Guy hasn't suggested
modeling a feedline but using the (virtual) feedline option in EZNEC, which
will serve Dave's purpose of calculating the impedances to be expected at
the bottom end of the feedline...
BTW, Ed, there is quite an interesting article on (explicit) modeling 2-wire
feedlines by Prof. Janzen, DF6SJ, in the German magazine "Der Funkamateur"
12/2004 and 1/2005 dealing with the shortcomings of NEC2 and ways to
overcome them...
so if you understand German it may be worthwhile to get hold of the
article...
unfortunately I do not have the facilities to turn it into a pdf-file, but I
can try to find somebody on our local contest reflector to do that for me
(and you)...
nevertheless, Dave should be ok with the method that Guy suggested as long
he is interested just in the impedance transformation of a specific
feedline...
regards from Germany
Uli, DJ2YA
----- Original Message -----
From: "K4SB" <k4sb@bellsouth.net>
To: <antennaware@contesting.com>
Sent: Monday, March 14, 2005 6:26 AM
Subject: Re: [Antennaware] Modelling transmission lines.
> "Guy Olinger, K2AV" wrote:
> > Many antenna programs have a method for placing a simple transmission
> > line in the model.
> >
> > EZNEC, for instance will allow you to define a very short wire (like
> > one inch) place it just about anywhere at a distance from the antenna
> > wire parts, and define a transmission line (including substituting a
> > specified length for the actual distance). You then place a source on
> > the short wire and you can run impedances on it. Great for coming up
> > with tuned feeder multiband solutions.
> --------------
>
> Have to agreeably disagree with Guy on this one. EZNEC does NOT like
> closely spaced lines according to the documentation, and segmentation
> on a 1" line at 160 meters would just not be reliable.
>
> One of the big problems with the NEC-2 engine, and I wish I had the
> answer.
>
> 73
> Ed
> _______________________________________________
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> Antennaware@contesting.com
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