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

It just keeps saying each line in that formula has a syntax error.
Hmm.

Well, I'll start reading all of that stuff... Maybe it will sink in.

On Wed, 24 Sep 2008 11:44:26 -0700 (PDT), wrote:

It just keeps saying each line in that formula has a syntax error.
Hmm.

Yep. I just got the same error (after wasting 30 mins doing updates).

"Syntax Error in external declaration: identifier CM"

CocoaNEC can't even parts a CM (comment) declaration. Something is
wrong. I found the examples for CocoaNEC at:
http://homepage.mac.com/chen/w7ay/Manuals/cocoaNEC/Manual/examples.html
which work as expected. I figured out that it wants to import a .NEC
files as a "spreadsheet". However, when I try that with the Jpole
file, I get "Cannot open xxxxx. File may have moved or been deleted".
After that, CocoaNEC "quits unexpectedly" and wants to know if it
should stay dead or restart. Lovely mess. I'll work on it some more
later tonite or this weekend. I may even RTFM.

Incidentally, my Mac G4 Cube only has 384MB of RAM, which may be the
problem.
http://en.wikipedia.org/wiki/Mac_Cube

Well, I'll start reading all of that stuff... Maybe it will sink in.

Not if you can't run a simple model with CocoaNEC. Have you
considered switching to the dark side and getting a PC? I haven't
tried running 4NEC2 or EZNEC under Bootcamp or one of the Windoze
emulators on OS/X but that might be worth a try.



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

On Wed, 24 Sep 2008 19:34:29 -0700, Jeff Liebermann
wrote:

It just keeps saying each line in that formula has a syntax error.
Hmm.

I broke down and read the documentation.
File - Import Card Deck
Load the Jpole.NEC file. It shows up correctly in the "card view" but
fails to appear in the "element inspector" and "spreadsheet view".

When I try to run it anyway, it complains with:
"NEC-2 error. Possible wire element that touches z=0".
No clue which card (line) it hates.

I'm going to give up in disgust for tonite.
Y're on your own for now.

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

On Sep 24, 8:13*pm, Jeff Liebermann wrote:
On Wed, 24 Sep 2008 19:34:29 -0700, Jeff Liebermann
wrote:

It just keeps saying each line in that formula has a syntax error.
Hmm.

I broke down and read the documentation. *
* File - Import Card Deck
Load the Jpole.NEC file. *It shows up correctly in the "card view" but
fails to appear in the "element inspector" and "spreadsheet view".

When I try to run it anyway, it complains with:
"NEC-2 error. *Possible wire element that touches z=0".
No clue which card (line) it hates.


Thanks for all the effort... With the exception of the app quitting, I
had all the exact same things happen. I could run XP on here, but it's
not worth it just for this. Seems like starting from scratch may be
the only way to go with this app. I'll keep at it.

Well, I've gotten a little farther... If Jeff or anybody that has
CoCoaNEC wants to take a look at this file, that would be great.

http://home.earthlink.net/~davepd/nec/

It's supposed to be a VHF log. I used an example file for an HF log to
compare it with and I think I have all the geometry for it right. But
it still doesn't run right. I know for a fact this antenna works in
the real world. Looking at the example log file, they only had the
smallest front element fed, which doesn't seem right to me, but that's
how I did mine. Maybe somebody has an idea how to feed all the
elements properly. The biggest problem is that the elevation pattern
is extremely spiked and the SWR is off the scale. Not sure what I'm
doing wrong.

On the slim-jim one... I have the basic wire shape, but I can't figure
out how to break the element in the right place on the stub side.

Dave

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.