| 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.

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

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.

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

On 8/19/2010 10:32 AM, wrote:
| From......: "Bill
| 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.

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

I like how everyone ignores the elephant in the room, thought I would
keep quite, sit back and see if anyone noticed the elephant stepping on
their foot--case of numb feet I guess.

So: What about MMANA-GAL. MMANA-GAL is about an exact work-a-like as
you can get to NEC. Is free, has no limitations in software, etc. Are
there any advantages to your program? Accuracy?

Regards,
JS

| "John Smith" wrote in message
| ...
| On 8/19/2010 10:32 AM, wrote:
|| From......: "Bill
|| 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.
|
| 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
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| I like how everyone ignores the elephant in the room, thought
| I would keep quite, sit back and see if anyone noticed the
| elephant stepping on their foot--case of numb feet I guess.
|
| So: What about MMANA-GAL. MMANA-GAL is about an exact
| work-a-like as you can get to NEC. Is free, has no
| limitations in software, etc. Are there any advantages to
| your program? Accuracy?
|
| Regards,
| JS
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Hello, again, JS!

For MMANA-GAL, I just took a look at:
http://mmhamsoft.amateur-radio.ca/pages/mmana-gal.php

where you can also read that, according to its developers,
this application is a descendant of MININEC, that is of NEC.
Therefore, there is no need to add nothing more on what already
written in some previous articles of this thread about VEMSA3D
and NEC.

Furthermore, I also just took a look at:
http://dl2kq.de/promm/

where you can read too that its developers clearly exhibit its
license and capabilities limitations. Therefore, there is also
no need to add nothing more on what they already wrote -not to
mention what it is lengthy said about software pattents and usage
restrictions in this tread.

Finally, the accuracy issue is also has been exhausted in
yesterday article:

| Sent......: Sunday, August 22, 2010 9:38 PM
| Newsgroups: sci.physics.electromag,rec.radio.amateur.antenna
| Subject...: vemsa3d 1.1 - a floss visual em simulator for
| 3d antennas
| From......:

so I have also nothing to add.

Well, after all, it seems that we only forgot to mention the
name of that elephant in the room -perhpas because its
advantageous name is /F/L/O/S/S/.

Best regards,

pez

On 8/22/2010 11:55 PM, wrote:

...
Well, after all, it seems that we only forgot to mention the
name of that elephant in the room -perhpas because its
advantageous name is /F/L/O/S/S/.

Best regards,

pez



Yes, the free, as in free beer is one great advantage, but an advantage
not all will be able to take advantage of. Since MMANA-GAL and EZNEC
have visual interfaces so similar, being able to use one is effectively
being able to immediately use the other. The learning curve into your
interface takes just a bit longer ... but, as you say, the availability
of the source makes it highly desirable to at least one group.

Thanks for the swift reply,
JS

| "John Smith" wrote in message
| ...
| On 8/22/2010 11:55 PM, wrote:
|
| ...
| Well, after all, it seems that we only forgot to mention the
| name of that elephant in the room -perhpas because its
| advantageous name is /F/L/O/S/S/.
|
| Best regards,
|
| pez
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| Yes, the free, as in free beer is one great advantage, but an
| advantage not all will be able to take advantage of. Since
| MMANA-GAL and EZNEC have visual interfaces so similar, being
| able to use one is effectively being able to immediately use
| the other. The learning curve into your interface takes just
| a bit longer ... but, as you say, the availability of the
| source makes it highly desirable to at least one group.
|
| Thanks for the swift reply,
| JS
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

You're very welcome!

But please take into account that our software is not free,
as in free beer or free gratis; is free, as in liberty, in
free speech or free libre*. Therefore, we don't support
license brokers, promote illegal code use or propagandize
software piracy.

Thank you very much for the chances you gave me to clearly
express our group point of view!

Kind regards,

pez

* Gratis versus Lib
http://en.wikipedia.org/wiki/Gratis_versus_Libre

wrote in message ...
| "John Smith" wrote in message
| ...
| On 8/22/2010 11:55 PM, wrote:
|
| ...
| Well, after all, it seems that we only forgot to mention the
| name of that elephant in the room -perhpas because its
| advantageous name is /F/L/O/S/S/.
|
| Best regards,
|
| pez
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
| Yes, the free, as in free beer is one great advantage, but an
| advantage not all will be able to take advantage of. Since
| MMANA-GAL and EZNEC have visual interfaces so similar, being
| able to use one is effectively being able to immediately use
| the other. The learning curve into your interface takes just
| a bit longer ... but, as you say, the availability of the
| source makes it highly desirable to at least one group.
|
| Thanks for the swift reply,
| JS
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

You're very welcome!

But please take into account that our software is not free,
as in free beer or free gratis; is free, as in liberty, in
free speech or free libre*. Therefore, we don't support
license brokers, promote illegal code use or propagandize
software piracy.

Thank you very much for the chances you gave me to clearly
express our group point of view!

Kind regards,

pez

* Gratis versus Lib
http://en.wikipedia.org/wiki/Gratis_versus_Libre

FYI I'll be posting information and links on your software on
antenneX.com's user group.

Antennex.com is, perhaps, the largest and most diverse website devoted
exclusively to antennas and related items. The website has both free (no
charge) and fee (charge for subscription) sections.

The user group is no charge and there are particiapnts from close to 100
countries with skill levels from enthusiastic amateur to world recognized
experts.

Bill

On 8/23/2010 12:42 PM, wrote:

...
You're very welcome!

But please take into account that our software is not free,
as in free beer or free gratis; is free, as in liberty, in
free speech or free libre*. Therefore, we don't support
license brokers, promote illegal code use or propagandize
software piracy.

Thank you very much for the chances you gave me to clearly
express our group point of view!

Kind regards,

pez

* Gratis versus Lib
http://en.wikipedia.org/wiki/Gratis_versus_Libre

Well, as you have seen, a concept such as "free" can mean many things to
many different people, splitting hairs on that is only a waste of time
some can engage in here ... However, I have downloaded the source, in
C++, and have been making notes and stub testing various parts. One
aspect of the source which really strikes me in the face, it is
un-commented! Ya' just gotta luv that software engineer! ROFLOL

Regards,
JS

| "John Smith" wrote in message
| ...
| On 8/23/2010 12:42 PM, wrote:
|
| ...
|
| Well, as you have seen, a concept such as "free" can mean
| many things to many different people, splitting hairs on that
| is only a waste of time some can engage in here ...
| However, I have downloaded the source, in C++, and have been
| making notes and stub testing various parts. One aspect of
| the source which really strikes me in the face, it is
| un-commented! Ya' just gotta luv that software engineer!
| ROFLOL
|
| Regards,
| JS
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Dear JS,

Thank you for pointed out this issue too!

As I already said, VEMSA3D is open source code, which is
distributed as free-libre; not free-gratis. Therefore, we
keep the right to publish full-comments about our source
code sometime in the future, as everybody else of course.
Please, see GNU GPL 3.0:
http://www.gnu.org/licenses/gpl.html

Free-gratis is the MS Windows application VEMSA3D, which
*everyone* can enjoy the production of it by simply following
the fully-commented instructions we already gave at the third
page, right column, of our paper:
http://arxiv.org/abs/1006.0031

Best regards,

pez, SV7BAX