I'm trying to create a model for a slim-jim type of jpole in NEC, but
I'm having a hard time figuring out how the coordinates should go in.
Can anybody help me with some hints? If I can get where each side
basically goes in X Y & Z and the feed, I can probably get the rest.
Or maybe there's a file online somewhere? I wouldn't mind figuring out
how to do a UHF/VHF log either. Thanks,

On Fri, 19 Sep 2008 01:13:20 -0700 (PDT), wrote:

I'm trying to create a model for a slim-jim type of jpole in NEC, but
I'm having a hard time figuring out how the coordinates should go in.
Can anybody help me with some hints? If I can get where each side
basically goes in X Y & Z and the feed, I can probably get the rest.
Or maybe there's a file online somewhere? I wouldn't mind figuring out
how to do a UHF/VHF log either. Thanks,

Draw either on a piece of graph paper. You will have your coordinates
that way when you mark up the grid.

73's
Richard Clark, KB7QHC

On Fri, 19 Sep 2008 01:13:20 -0700 (PDT), wrote:

I'm trying to create a model for a slim-jim type of jpole in NEC, but
I'm having a hard time figuring out how the coordinates should go in.
Can anybody help me with some hints? If I can get where each side
basically goes in X Y & Z and the feed, I can probably get the rest.
Or maybe there's a file online somewhere? I wouldn't mind figuring out
how to do a UHF/VHF log either. Thanks,

Go unto:
http://mmhamsoft.amateur-radio.ca/mmana/index.htm
and download MMABA-GAL modeling software. It's free. Included in the
samples is a 145MHz J-Pole antenna as:
\ANT\VHF\J-ant144.mma

For NEC2 output, see utility at:
http://www.qsl.net/ua3avr/
which is the same engine used for 4NEC2 (by the same author).

More antenna models at:
http://dl2kq.de/mmana/4-3.htm

--
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:
[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?

Just a thought,
regards,
JS

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