wrote in message ...
| From......: "Bill Miller"
| Newsgroups: sci.physics.electromag
| Sent......: Wednesday, August 18, 2010 10:44 PM
| Subject...: vemsa3d 1.1 - a floss visual em simulator for 3d
antennas
|
| wrote in message ...
| -
| ...
|
| How does this work differ from NEC Numeric Electromagnetic Code for
antenna
| analysis?
|
| Bill Miller
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Dear Mr. Miller,

VEMSA3D can not work differently, because it is based
on the same theoretical method as NEC does, that is on
the Method of Moments.

However, since each of these numerical applications use
a different basis of the current function space and since
their corresponding computer programs use unavoidably
finite linear combinations of them, in general, they
produce different results.

Can you quantify further or explain the nature of thes "different results?"

Are there certain classes of antennas for which VEMSA3D might produce more
accurate results than NEC?

Thanks!

Bill Miller



To be specific, the two bases details are included in the
following:

VEMSA3D current basis:
J. H. Rischmond, Radiation and Scattering by Thin-Wire
Structues in the Complex Freqeuncy Domain, (15), p.6
http://tinyurl.com/24zwycy

NEC current basis:
G. J. Burke, A. G. Poggio
Numerical Electromagnetics Code - Method of Moments
Equation (20), p. 11
http://www.si-list.net/NEC_Archives/nec2prt1.pdf

Regards,

Petros Zimourtopoulos

| "Bill Miller" wrote in message
| ...
|
| wrote in message
| ...
|| From......: "Bill Miller"
|| Newsgroups: sci.physics.electromag
|| Sent......: Wednesday, August 18, 2010 10:44 PM
|| Subject...: vemsa3d 1.1 - a floss visual em simulator
|| for 3d antennas
||
|| wrote in message ...
|| -
|| ...
||
|| How does this work differ from NEC Numeric Electromagnetic
|| Code for antenna analysis?
||
|| Bill Miller
| - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| Dear Mr. Miller,
|
| VEMSA3D can not work differently, because it is based
| on the same theoretical method as NEC does, that is on
| the Method of Moments.
|
| However, since each of these numerical applications use
| a different basis of the current function space and since
| their corresponding computer programs use unavoidably
| finite linear combinations of them, in general, they
| produce different results.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| Can you quantify further or explain the nature of thes
| "different results?"
|
| - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Well, I can try. These numerically different results are due
to the different coupling -reaction, or impedance- between two
current distributions for which different function -expression,
type, formula, or equation- is used to describe them in each
one of the two applications, VEMSA3D and NEC.

2
| - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| Are there certain classes of antennas for which VEMSA3D
| might produce more accurate results than NEC?
|
| Thanks!
|
| Bill Miller
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

You are welcome!

VEMSA3D is a thin-wire polygonal modeler in "free space".
Therefore, it has to "exactly" predict or justify the
characteristics of any thin-wire antenna. For this class of
antennas VEMSA3D can be certainly compared with NEC. Anyhow,
this comparison can only be indirect: you have to build and
measure the specific thin-wire antenna first and then to
overlay the results of both applications upon the
measurements. But since this kind of knowledge is definitely
a posteriori, you can try a comparison of both applications
for *any* class of antennas. Here, only the advertisement
builds knowledge a priori; but usually this is followed by
a deep disillusionment.

Regards,

Petros Zimourtopoulos