[TowerTalk] antenna modeling software newbie

[jimlux]

On 7/13/19 6:02 PM, Jamie WW3S wrote:
> Whats a good entry level modeling program, I'm interested in learning 
> more about modeling, and running different models on a 2 element beam, 
> comparing 2 different boom lengths.

On Windows:

4nec2 and eznec are probably the two you should consider, both have a 
variety of ways to enter the geometry, both have decent graphics, etc.

4nec2 is free

there's a free starter edition of eznec with the ARRL antenna book

Both run the NEC2 engine underneath.

I've used 4nec2 for decades now, so I'm used to it. Folks who have used 
EZNEC for decades are used to it.

Both generate decent output.

Both will run the NEC4 engine if you license it from Lawrence Livermore 
National Lab.

Both have features to make things like tapered elements, etc. easier.



On Mac:
CocoaNEC - free - runs the NEC2 engine, has appropriate editors and 
display options - I have a Mac, but I'm so used to 4nec2, I run 
parallels.  It has a lot of nifty features.


ALL of the above have ways to have "calculations" in the model 
description which is really, really useful.  For instance, maybe you 
want a drooping dipole, and you want to fool with different support 
heights and droop angles.. You can do it.




On Linux:

Cowboy/cowgirl up and use your favorite editor (vi, emacs, nano, cat ) 
to build card image decks, and run it from the command line, like the 
modeling gods intended. Read the line printer output with columns of 
numbers to figure out what the pattern is.

Write shell scripts or python or whatever to do optimizing.

(There actually is a fair amount of stuff out there to run NEC on Linux, 
some of which purports to have graphical interfaces, but I've never 
contemplated it..




Any of these is sufficient to fool with a 2 element beam, and all of 
them come with samples to start with (which is invaluable!! - the NEC 
input deck format is not exactly self explanatory, but after a while 
everything makes sense.

Virtually all versions of NEC (including commandline versions) do not 
require strict adherence to the column formatting in the original 
FORTRAN version.  White space serves as a delimiter.



---

There's a lot of tricks that are non-obvious, but make sense once you 
know them.  Ask...

(I just figured out how to have it compute the pattern of the antenna 
inside the ground under a low dipole, for instance.  )