On Sat, 20 Sep 2008 19:49:21 -0700, John Smith
wrote:

Jeff Liebermann wrote:
[stuff]

What amazed me, after looking them both over, eznec/mmana-gal, the
similarities are greater than their differences ... could the
instructions/examples from eznec be useful?

Yep. 4NEC2 will open .EZ files from EZNEC directly. I'm not very
familiar with MMANA-GAL but it appears that Ari's utility will both
import and export .NEC files.

Any tutorial from any vendor is useful. There's no reason to just use
one modeling program. If you had a workshop, would you use one tool
for every job? Probably not. If you sign in to the free Antennex
"guest room", there's a rather long and detailed NEC2 manual, along
with lots of tutorials and articles from back issues.

However, despite the wealth of tutorials and articles, I find it best
to learn by destroying. I hate to recommend my method because it's
not for everyone, but I like to start with a similar model, and
butcher it so I know how it works and what it does. If I can't figure
out how to do something, I search and read the docs. Not the best
method, but works for me.

I use mostly 4NEC2 because I'm familiar with it and because it
includes a surface, dish, cylinder, etc generator. I sometimes use
the free version of EZNEC, because it's somewhat easier to use. I
also use NEC-Win Synth to build tower and geometric structures:
http://www.nittany-scientific.com/nws/index.htm

There are lots of antennas available at various sites to plagerize.
For example:
http://www.nittany-scientific.com/examples.htm
http://www.cebik.com
http://www.antennex.com

Drivel:
Various commercial digital TV antennas:
http://www.hdtvprimer.com/ANTENNAS/comparing.html
with Eznec NEC2 files at:
http://hometown.aol.com/kq6qv/SIMS/
I'm amazed at how well some of these antennas work over the very wide
TV VHF/UHF range. In the past, I've assumed that much of the metal
work on the typical TV antenna were decorations and that the antenna
was at best a marginal proposition. Apparently not, as most of the
commercial antennas seem to be rather well designed.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
[real stuff]

Uh, Jeff ...

Eznec vs. Mmana-Gal ... be careful--play dumb ... :-)

Regards,
JS

On Sat, 20 Sep 2008 21:15:01 -0700, John Smith
wrote:

Jeff Liebermann wrote:
[real stuff]

Uh, Jeff ...
Eznec vs. Mmana-Gal ... be careful--play dumb ... :-)

You left out about a dozen other packages including 4NEC2. I've never
played dumb and don't plan to start now. What am I missing? Some
kind of religious issues in modeling software? A battle to the death
between the fanatics? Conflicting results?

Well, actually.... I did play dumb once. I came face to face with a
mountain lion on a hiking trail. Trying to act non-threatening does
not come naturally to me.

Incidentally, MMANA-GAL Yahoo Group:
http://groups.yahoo.com/group/MM-HAMSOFT/

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for the help... I'm actually using cocoaNEC for OSX, so
unfortunately I can't use those files. Otherwise that would probably
be a big help. I know if I could just see one example of each, I could
adjust the rest myself.

On Tue, 23 Sep 2008 17:40:28 -0700 (PDT), wrote:

Thanks for the help... I'm actually using cocoaNEC for OSX, so
unfortunately I can't use those files. Otherwise that would probably
be a big help. I know if I could just see one example of each, I could
adjust the rest myself.

No problem. We'll do it differently and easier. Here's the NEC2 file
for a 145MHz JPole for stolen from the 4NEC2 samples.
http://802.11junk.com/jeffl/crud/J-ant.nec

I just discovered that the conversion program from .MMA to .NEC will
generate a perfectly usable .OUT file, but not a .NEC input file. I'm
probably doing something wrong, but I don't have time to debug it
right now.

Note to self: Make an index of .NEC files. It's becoming difficult
to find specific antennas.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for the effort Jeff, but for some reason it doesn't seem to be
compatible. It won't open as an NEC file and I also tried giving it
just an NC tag. The closest I can get is importing it as a card deck,
but it says it has errors, and when I look at the code, it looks
totally different from other formulas that do work in the app.

Art, it does have variables... I don't know if the segments are
unlimited. It seems to work great with the included files. Normally
I'm pretty good at this stuff. I can do my own html and some other
code stuff, but I'm just having difficulty getting a grasp on this for
some reason. I did find a tutorial for NEC and read the whole thing,
but it didn't help much. I guess I'm not great with the scientific
stuff.

Dave

On Tue, 23 Sep 2008 22:50:04 -0700 (PDT), wrote:

Thanks for the effort Jeff, but for some reason it doesn't seem to be
compatible.

Can you read the .NEC file as a text file with an editor? I might
have tossed in a few extra carriage returns, word wrapped it, or
something equally stupid. Maybe some extra characters at the
beginning or end?

It won't open as an NEC file and I also tried giving it
just an NC tag. The closest I can get is importing it as a card deck,
but it says it has errors, and when I look at the code, it looks
totally different from other formulas that do work in the app.

An NEC file is a card deck. I have a Mac Cube with OS/X sitting in
the office. When I have time (which means after Sunday), I'll see if
I can feed it to cocoaNEC and see what breaks.

I'm pretty good at this stuff. I can do my own html and some other
code stuff, but I'm just having difficulty getting a grasp on this for
some reason. I did find a tutorial for NEC and read the whole thing,
but it didn't help much. I guess I'm not great with the scientific
stuff.

NEC user guide and manuals:
http://www.nec2.org

EZNEC 5 manual:
http://www.eznec.com/ez50manual.html

Basic Antenna Modeling by L.B. Cebik:
http://www.nittany-scientific.com/book/index_beg.htm

Advanced Antenna Modeling by L.B. Cebik:
http://www.nittany-scientific.com/book/index_inter.htm

Antennex Guest Room:
http://www.antennex.com/guests.html
Get a login and password. Lots of goodies inside including plenty of
tech articles, CD's full of past issues, etc.

ARRL Antenna Modeling page with plenty of documents and links at the
bottom of the page:
http://www2.arrl.org/tis/info/HTML/antenna-modeling/index.html

NEC misc programs, docs, examples, whatever. Somewhat old:
http://www.si-list.net/swindex.html

There's probably more but that should keep you occupied for a while.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 23 Sep 2008 22:50:04 -0700 (PDT), wrote:

Thanks for the effort Jeff, but for some reason it doesn't seem to be
compatible.

Ok, if all else fails, we use brute force.

-------- cut here ------------

CM J-antenna 144MHz
CE

sy H=7.12 ' Height above ground

SY l1=0.47, la=H+l1
SY l2=1.483, lb=H+l2

GW 1 20 0.0 0.0 la 0.0 0.0 lb .003
GW 2 10 0.0 0.0 la 0.0 0.0 H .003

SY d=0.0354, dd=H-d
GW 3 1 0.0 0.0 H 0.0 0.0 dd .003
GW 4 1 0.0 0.0 dd 0.0 .01 dd .003
GW 5 1 0.0 .01 dd 0.0 .01 H .003
GW 6 10 0.0 .01 H 0.0 .01 la .003
GW 7 1 0.0 0.0 H 0.0 .01 H .003
GE 1

EK
LD 5 0 0 0 25000000
GN 2 0 0 0 13 0.005 0.0 0.0
EX 0 7 1 0 1.0 0.0
FR 0 1 0 0 145 1
EN

-------- cut here ------------

What can go wrong, go wrong, go wrong, go wrong....


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

wrote:
Thanks for the effort Jeff, but for some reason it doesn't seem to be
compatible. It won't open as an NEC file and I also tried giving it
just an NC tag. The closest I can get is importing it as a card deck,
but it says it has errors, and when I look at the code, it looks
totally different from other formulas that do work in the app.

Art, it does have variables... I don't know if the segments are
unlimited. It seems to work great with the included files. Normally
I'm pretty good at this stuff. I can do my own html and some other
code stuff, but I'm just having difficulty getting a grasp on this for
some reason. I did find a tutorial for NEC and read the whole thing,
but it didn't help much. I guess I'm not great with the scientific
stuff.


NEC takes some getting used to, and, the tutorials that come with it are
aimed at computational electromagnetics folks, who already understand
how NEC works under the hood, and are really looking at "how do I put my
problem into a form for THIS particular code".

There's some pretty common "tricks of the trade" used with NEC, like
using a network to create a current source (4nec2 does this for you
automatically).

Mostly, though, it's just slogging through it the first few months until
you get your mind wrapped around the conceptual model.

Start with something fairly simple (but non trivial).. like a multiband
dipole or a 3 element Yagi with just wires (i.e. don't start out trying
to model the U-bolts and stuff).

A dipole is nice to fool with, because you can put a wire in under it to
represent a tower, for instance, and see what effect it has on the
pattern. Likewise, you can do something like model your rain gutters or
the feedline as a single wire, and see how much current is induced in them.

On Sep 21, 12:11*am, Jeff Liebermann wrote:
On Sat, 20 Sep 2008 21:15:01 -0700, John Smith

wrote:
Jeff Liebermann wrote:
[real stuff]

Uh, Jeff ...
Eznec vs. Mmana-Gal ... be careful--play dumb ... :-)

You left out about a dozen other packages including 4NEC2. *I've never
played dumb and don't plan to start now. *What am I missing? *Some
kind of religious issues in modeling software? *A battle to the death
between the fanatics? *Conflicting results?

Well, actually.... I did play dumb once. *I came face to face with a
mountain lion on a hiking trail. *Trying to act non-threatening does
not come naturally to me.




Incidentally, MMANA-GAL Yahoo Group:
http://groups.yahoo.com/group/MM-HAMSOFT/


Does this have unlimited segments and variableswith it's optimizer?








--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558