On Tue, 23 Sep 2008 19:09:10 -0700 (PDT), Art Unwin
wrote:

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

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

I couldn't find any documentation as to the program limits. As I
understand it, MMANA-GAL has a stripped down NEC2 engine. 4NEC2 and
EZNEC use the full NEC2 engine from Lawrence Livermore Labs. I'm not
sure what you're building but allow me to offer a clue. I recently
threw together a model of a truly ugly tower with about 8000 segments
including about 2000 pattern lines for various grids and reflectors.
After about 14 hours running, my PIII/933MHz finally spewed out a
result (that told me that I goofed and had to make corrections). I
dragged home a P4/2.8GHz with hyperthreading, which took about 8 hours
to run. This was getting ridiculous, so I dragged the program and
model to a customers office, and ran it overnight on his P4 2.8GHz
dual core, 4GB RAM, 1333MHz FSB, SATA2 drive, etc. It doesn't get
much better. It ran in 3 hours.

The optimizer isn't much better. It will automagically tweak
dimensions to meet a pre-defined set of criteria. If you set the
final criteria too close to perfection, you may get an answer after
the next ice age.

Anyway, I suggest you use a machine with lots of horsepower and start
with EZNEC, 4NEC2, NEC-WIN, MMANA-GAL, or other modeling program using
some of the sample files included with each program. Once you have
figured out how to manipulate and modify those, you can step up to
more complexicated models (such has the giant mess I stupidly created
by throwing every piece of metal on the tower into the model).

--
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:

I couldn't find any documentation as to the program limits. As I
understand it, MMANA-GAL has a stripped down NEC2 engine. 4NEC2 and
EZNEC use the full NEC2 engine from Lawrence Livermore Labs. I'm not
sure what you're building but allow me to offer a clue. I recently
threw together a model of a truly ugly tower with about 8000 segments
including about 2000 pattern lines for various grids and reflectors.
After about 14 hours running, my PIII/933MHz finally spewed out a
result (that told me that I goofed and had to make corrections). I
dragged home a P4/2.8GHz with hyperthreading, which took about 8 hours
to run. This was getting ridiculous, so I dragged the program and
model to a customers office, and ran it overnight on his P4 2.8GHz
dual core, 4GB RAM, 1333MHz FSB, SATA2 drive, etc. It doesn't get
much better. It ran in 3 hours.


If your optimization is just changing a small part of the overall
structure (e.g. the position of an antenna on the tower), then you
should be looking at the Write Greens Function and Read Greens Function
cards.
http://www.nec2.org/part_3/ngf.html

This is how they do things like analyze antenna placement on a ship or ISS.

On Wed, 24 Sep 2008 10:39:47 -0700, Jim Lux
wrote:

If your optimization is just changing a small part of the overall
structure (e.g. the position of an antenna on the tower), then you
should be looking at the Write Greens Function and Read Greens Function
cards.
http://www.nec2.org/part_3/ngf.html

This is how they do things like analyze antenna placement on a ship or ISS.

Thanks. I haven't done much with the optimizer beyond tinkering to
see how it works. I've never tried the NGF feature, but it certainly
looks interesting. Looking at the above page, I'm instantly lost.
However, I'll be taking yet another medical vacation shortly, so I'll
have plenty of time to RTFM.

Incidentally, the tower in question is at a friends radio site. It's
loaded with a mixture of commercial, FM translator, and ham systems.
There was almost no planning in the tower antenna arrangement. The 2
ton gorilla in the mix are 3ea 250 watt 900MHz paging xmitters, that
are causing problems with the other users. I can't touch their
antennas because they pay the bulk of the bills. There are also some
nulls that need to be moved to placate some of the customers. I'm
trying to first model, and later optimize the location of the other
antennas. So far, simple solutions like vertical isolation and
positioning antennas on opposite sides of the tower from the paging
antennas look promising. Sorry, no photos as the owner wants me to
keep the location secret.

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