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Old September 25th 08, 02:29 AM posted to rec.radio.amateur.antenna
Jeff Liebermann[_2_] Jeff Liebermann[_2_] is offline
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First recorded activity by RadioBanter: Jun 2007
Posts: 1,336
Default Help with slim jim nec model

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.

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