RE: NEC-LIST:Re: Accuracy

All:

There are code vs code comparisons, but there are also code vs measurements
comparisons. I did the latter for Jim Breakall when he was at Lawrence
Livermore National Laboratory (LLNL) with Gerry Burke some years ago when
Nec-3 came out. NEC-3 did great. There is, with any MOM code, the challenge of
getting the segmentation right, etc. You need something to use as the
"standard" against which to compare the others. The code developed at Penn
State by Doug Werner, using the exact solution for the magnetic vector
potential of cylindrical wires of arbitrary radius is a good candidate for
such a standard. Doug has published some example calculations that could be
used to benchmark other code results. Perhaps Doug could post some of them to
NEC-List.

George
George
Original Message:
-----------------
From: R.P.Haviland bobh_at_iag.net
Date: Sun, 14 Oct 2001 20:03:04 -0400
To: bibby_at_mediaone.net, kentenna_at_yahoo.com, nec-list_at_gweep.ca
Subject: NEC-LIST:Re: Accuracy

Of course, all antenna anaylsis program use a series of approximations, so
the result are approximate. The standard test is run several simulations,
starting with a small number of segments, and increasing towards the maximum
allowed by the
program; if the results appear to converge towards a constant value, the
results are dependable.

I have compared NEC, Mininec 1-3 and the ohio state program (see separate
posting for sources) on a few difficult antennas, such a loops. NEC and the
ohio state program agree well, with mininec showing an 'offset". I have not
tried the later versions of mininec.
w4mb

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