Re: NEC-LIST: OS X NEC versions

At 9:03 PM -0400 9/1/08, Wipf Heinz wrote:
>I am looking around for available OS X NEC versions
>on the internet.

I do not know of a Mac OS X version of NEC-4. However, an excellent
version of NEC-2 is available for Mac OS X. It is cocoaNEC,
available from
<http://homepage.mac.com/chen/w7ay/cocoaNEC/index.html>.

A few months ago, others and I tested several versions of NEC-2 with
an antenna model having many segments, including closely spaced
segments and segments that join with small angles between them.
(This model accurately represented a real antenna that is made of
wire and that I use for frequencies ranging from 1.8 to 29.7 MHz. I
will provide details if asked.) The NEC-2 versions that we tested
included several Windows and two Macintosh executables.

The ONLY version of NEC-2 that produced accurate results was
cocoaNEC, when cocoaNEC's quadruple-precision option was enabled.
All the double-prcision (REAL*8) versions crashed and burned.

No version of NEC-2 could compute feedpoint impedance or radiation
pattern accurately if lossy dielectric ground was within the near
field of the antenna. However, with the antenna modeled in free
space (no ground plane) or with perfectly electrically conducting
ground within the near field, cocoaNEC's results matched NEC-4's
results quite well.

Chuck, W1HIS

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