Hi,


Last friday, there was a (very interesting) talk in a radioclub here on
the topic of using 4nec2 for antenna-modelling.

Afterwards, we had a discussion about it, ... and also about using the
tool in the classes for getting your ham-radio license, especially for
visualising radiation-patterns.
(e.g. the radiational pattern of a dipole antenne at 2 meter above
ground and at wavelength/2 above ground)


The most logical thing to do is provide a number of prepared
antenna-models beforehand and teach the people giving these clases to
use nec, ... but the people giving these classes are not necessairy
people very comfortable with these tools.


I know there is the possible to export radio-patterns into a format that
can easily to viewed in 3D?

Or does anybod see other opions?

Perhaps using necpp, python and one of the visuealisation libraries for
python?


This is intended for people using windows or mac.



Thanks in advance for any advice.

73
kristoff - ON1ARF

On Sun, 25 Mar 2018 15:26:54 +0200, kristoff
wrote:

I know there is the possible to export radio-patterns into a format that
can easily to viewed in 3D?

Some antennas (not all are my designs) in 4NEC2:
http://802.11junk.com/jeffl/antennas/

I asked Arie Voors (author of 4NEC2) if he could provide such a
feature. I'll spare you the details, but basically the answer was no.
Try your luck in his forum:
https://www.tapatalk.com/groups/fornectoo/

What I had to do was:
- Screen grab the output using altPrtScr and paste to Irfanview.
- Resize to a standard JPG size.
- Save all the screen grabs to an empty directory.
- Use Jalbum to create a "photo album".
- From the starting image, typically named the same as the
antenna, save the NEC deck, and hand edit the HTML.

For example:
http://802.11junk.com/jeffl/antennas/AMOS-5-1090MHz/index.html
Notice that the NEC deck below the JPG of the main page:
Main page:
http://802.11junk.com/jeffl/antennas/AMOS-5-1090MHz/amos-5-1090.jpg
NEC deck:
http://802.11junk.com/jeffl/antennas/AMOS-5-1090MHz/amos-5-1090.nec
TXT file:
http://802.11junk.com/jeffl/antennas/AMOS-5-1090MHz/amos-5-1090.txt
in the form:
PRE
(NEC deck and comments
/PRE
I probably forgot something, but this should get you started. The
reason for the .txt file is that Jalbum would not display a text file,
only graphic images. This mess was the least disgusting workaround.

I had some ideas for creating a template for displaying 4NEC2 files
but never did anything with the idea. Need a project?

Jalbum:
https://jalbum.net/en/
Irfanview:
https://www.irfanview.com

You can also do animated GIF files with a series of antenna patterns:
Static:
http://802.11junk.com/jeffl/antennas/vertical-dipole/index.html
Animated:
http://802.11junk.com/jeffl/antennas/vertical-dipole/slides/animated-v-dipole.html

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Hi jeff and Jeff,


Thanks both for replying.



To limit the number of mails, I'll reply to both of you in one mail.


Jeff,

Thanks. I am aware of that. As this is only for visualitation, I'm just
looking at the different options out there.
The people giving ham-radio classes are not necessairy people who have a
very solid background in computers, so that is why as I was looking for
an option that is as simple as possible to use.





On 25-03-18 19:39, Jeff Liebermann wrote:
On Sun, 25 Mar 2018 15:26:54 +0200, kristoff
wrote:

I know there is the possible to export radio-patterns into a format that
can easily to viewed in 3D?

Some antennas (not all are my designs) in 4NEC2:
http://802.11junk.com/jeffl/antennas/

I asked Arie Voors (author of 4NEC2) if he could provide such a
feature. I'll spare you the details, but basically the answer was no.

To bad 4nec2 isn't open source.



I'll concidering writing something myself to do this as there are python
libraries that interact with nec directly.
Perhaps it would be a good exercise to learn more about the 3D plotting
libraries in python.

You methode looks interessing but seams to require a lot of manual work.

I'm a bit surprised there are no standard way to visualise 3D wireframes
objects.


Kristoff

On Tue, 27 Mar 2018 18:27:42 +0200, kristoff
wrote:

I'll concidering writing something myself to do this as there are python
libraries that interact with nec directly.
Perhaps it would be a good exercise to learn more about the 3D plotting
libraries in python.

I'm confused. Do you want to "plot" the output in 3D or do your want
to "visualize" the output in 3D? Plotting implies a 2D display, such
as an LCD display, projector, or piece of paper. Visualization
implies the use of a HUD (heads up display), polarizing glasses, or if
desperate, anaglyph glasses. Which are you looking for?

I just did some searching for antenna models that used anaglyphs.
Nothing found.

It shouldn't be too difficult to make a movie or viewer using only
4NEC2 3D screen output. When viewing an antenna, capture the current
3D screen as well as the next screen after about a 2 degree rotation.
Convert one image to shades of red, the other to shades of blue.
Conglomerate into an anaglyph image. With blue/red glasses, you
should see it in 3D. The difficult part will be determining the
rotating angle and antenna size that corresponds to the spacing
between your eyes. Then, writing a program that captures successive
frames and creates the anaglyph.

Your method looks interessing but seems to require a lot of manual work.

Yep. I could automate the process with a scripting language or even
keyboard macros. Not a big deal, but without a paying customer, I'm
just too lazy to do it.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff,


(inline comments)

On 28-03-18 08:44, Jeff wrote:
I don't see what is not simple about loading a pre recorded .out file
into 4nec2 and viewing it in the 3D viewer? It is just as simple as
loading a file into any other viewer. There is no calculation or
analysis involved.

During the talk about antenna-modelling in that radioclub last week, the
first reaction of the audience when the presenter opened 4nec2 was
"pppfff .. so many menus and windows". :-)

Anycase, it would be nice to be able to view multiple 3D
radiation-patterns in one view (e.g. a 3, 6 and 9 element yagi) all with
one and the same scale.


Jeff
Kristoff