RE: NEC-LIST: An interface to NEC in Mathematica

Wayne:

You raise several interesting points:

1. Interfaces for NEC, and

2. How to treat dielectrics and ferromagnetics in programs such as
NEC.

3. Optimizers

Regarding the former, it would be useful to have relatively standard
interfaces to MATLAB, Mathcad, and Mathematica. I know several folks
have spent a lot of their own time doing their own custom interfaces
to MATLAB and Mathcad. Leveraging these powerful programs is a very
good idea. Maybe NEC-LIST can serve as a software exchange for info
and subroutines of the type you mention. Also, the ACES Newsletter and
the ACES Journal are media appropriate for such "work offline" sharing
of similar info. Good luck with this and thanks for your willingness
to share.

Regarding dielectric, ferromagnetic, and even chiral media, there are
various ways to work this. In the 1960s, I looked into the use of
"artificial dielectrics" to emulate "jungle". So I am confident that
you can use this method in NEC, if you have the patience to generate
the structures. You may want to look into the literature of chiral
media, and how they are modeled, to get some insights on how to model
conducting structures with such media surrounding them. Papers by the
group at the University of Pennsylvania come to mind (e.g., Jaggard,
et al.). If you set up for chiral media, you can treat other cases
(e.g., just one or the other) as subsets.

Regarding optimizers, I got my first dose of that in discussions with
Jim Breakall of Penn State. He and students generated a commercial
product for that purpose, and others have also. More recently the guys
at the University of Illinois, and Raj Mittra and colleagues (e.g.,
Ping Werner, et al.) at Penn State have used the genetic algorithm to
good use. Certainly the use of NEC as part of such an optimizer makes
it important to have efficient algorithms when you need to go through
many generations to reach your "quasi-optimum" result.

So is it time for NEC-LIST to have sublists?

Good luck in your endeavors, and thanks again for your willingness to
share the fruits of your labors.

Regards,

George Hagn

Original Message:
-----------------
From: Wayne Shanks wshanks3_at_home.com
Date: Fri, 26 Jan 2001 23:35:17 -0200
To: nec-list_at_ee.ubc.ca
Subject: NEC-LIST: An interface to NEC in Mathematica

My name is Wayne Shanks

I am a RF engineer with a BS in physics.

I am now working on printed antenna designs.
I am using Microwave office 2000 and some other RF design packages, but
I would like to use NEC to do some of my more ambitious antenna designs
and optimizations.

I would like to implement genetic algorithm and possibly simulated
annealing to search for good solution to some of my problems.

To this end I am writing an interface to NEC in Mathematica.

I currently have about a dozen NEC commands implemented in Mathematica.

I will be happy to share this system with the group.

I hope I can get suggestions and pick some of your brain on the finer
points of NEC.

Perhaps a few of you might like to contribute a subroutine.

Attached with this message is my Mathematica interface so far.

[Since attachments are not permitted, I've uploaded the file to

 http://members.home.net/nec-list/NEC_antenna_001.nb (13 kB) -- DGM]

If you have Mathematica, put this Mathematics notebook in the same
directory as your NEC executable.

Currently I am using "Nec2d1k4", but that can be changed easily in the
definition of the "Spawn" command.

Currently documentation is next to nothing, but I will add things as I
go along.

Here is my first question.....

can you simulate a dielectric or feroelectric object with a patch or
wire mesh frame with mostly imaginary impedance?

Ideally I would like to make a Mathematica subroutine that can
automatically create a rectangular or triangular mesh with the desired
electrical properties.

Wayne Shanks

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Received on Mon Jan 29 2001 - 13:31:57 EST