You can select NEC-4, but that requires downloading some source code, getting a fortran compiler and building the NEC-4 app.
Plus $300 for the license, heh.

Try this NEC file, same as above, except converted to metric and XQ and EN included.

CM NEC file by 300ohm
CM Dimensions per Escape Velocity
CM Length of each diagonal sub-section = 7 inches
CM Gap at feedpont = 2 inches
CM Length of stubs 5 inches
CM Rod reflectors with a gap of 1.5 inches and with the following lengths
CM - Top and Bottom = 14" + 1.5" + 14" = 29.5"
CM - Middle = 10" + 1.5" + 10" = 21.5"
CM - Reflector Spacing = 4 inches
CE
GW 19 15 0.1016 -0.0254 2.1209 0.1016 -0.15875 2.00025 1.02626e-3
GW 20 15 0.1016 -0.15875 2.00025 0.1016 -0.0254 1.8796 1.02626e-3
GW 21 15 0.1016 -0.0254 1.8796 0.1016 -0.15875 1.75895 1.02626e-3
GW 22 15 0.1016 -0.15875 1.75895 0.1016 -0.0254 1.6383 1.02626e-3
GW 23 15 0.1016 -0.0254 1.6383 0.1016 -0.15875 1.51765 1.02626e-3
GW 24 11 0.1016 -0.15875 1.51765 0.1016 -0.28575 1.51765 1.02626e-3
GW 25 15 0.1016 -0.0254 2.1209 0.1016 -0.15875 2.24155 1.02626e-3
GW 26 11 0.1016 -0.15875 2.24155 0.1016 -0.28575 2.24155 1.02626e-3
GW 27 15 0.1016 0.0254 2.1209 0.1016 0.15875 2.00025 1.02626e-3
GW 28 15 0.1016 0.15875 2.00025 0.1016 0.0254 1.8796 1.02626e-3
GW 29 15 0.1016 0.0254 1.8796 0.1016 0.15875 1.75895 1.02626e-3
GW 30 15 0.1016 0.15875 1.75895 0.1016 0.0254 1.6383 1.02626e-3
GW 31 15 0.1016 0.0254 1.6383 0.1016 0.15875 1.51765 1.02626e-3
GW 32 11 0.1016 0.15875 1.51765 0.1016 0.28575 1.51765 1.02626e-3
GW 33 15 0.1016 0.0254 2.1209 0.1016 0.15875 2.24155 1.02626e-3
GW 34 11 0.1016 0.15875 2.24155 0.1016 0.28575 2.24155 1.02626e-3
GW 35 5 0.1016 -0.0254 1.8796 0.1016 0.0254 1.8796 7.24766e-4
GW 36 29 0 -0.01905 1.524 0 -0.37465 1.524 4.7625e-3
GW 37 21 0 -0.01905 1.7526 0 -0.27305 1.7526 4.7625e-3
GW 38 21 0 -0.01905 2.0066 0 -0.27305 2.0066 4.7625e-3
GW 39 29 0 -0.01905 2.2352 0 -0.37465 2.2352 4.7625e-3
GW 40 29 0 0.01905 2.2352 0 0.37465 2.2352 4.7625e-3
GW 41 21 0 0.01905 2.0066 0 0.27305 2.0066 4.7625e-3
GW 42 21 0 0.01905 1.7526 0 0.27305 1.7526 4.7625e-3
GW 43 29 0 0.01905 1.524 0 0.37465 1.524 4.7625e-3
GE 0
EK
EX 0 35 3 0 1 0
GN -1
FR 0 1 0 0 473 0
RP 0 1 73 1510 90. 0. 1 5 0. 0.
XQ
EN

Still no go on the file. I'm going to take a look at this again tomorrow. I'm using Snow Leopard (OS X 10.6) so maybe there is an incompatibility. I'll try on 10.5 and 10.4 and a older PPC Mac to see if there is some OS X compatibility issue.

"It might be time to invite W7AY here to give advice on his CocoaNEC program."

That's a great idea. I sort of put the Nec modeling on the back burner, but I really wanted to look at all the NEC files posted here to learn more. There are plenty of ideas in my head I'd like to try and I really like the CocoaNec interface.

If the tab spacings are not being correctly represented It may be that CocoaNec and 4Nec2 are using different default text encodings.
I tried a bunch of different text encodings and line endings. None of those made any difference.

Try this NEC file, same as above, except converted to metric and XQ and EN included.

I converted the tabs to spaces (it's a simple find and replace all in TextEdit) and that worked! (Oh, and I'm running 10.6 as well)

Obligatory Screenshot:
http://img695.imageshack.us/img695/5500/screenshot20100107at211.th.png (http://img695.imageshack.us/i/screenshot20100107at211.png/)

"I converted the tabs to spaces (it's a simple find and replace all in TextEdit) and that worked!"

Awesome. How did you get it to find tabs, everytime I press the tab key it would go to the next textfield instead of searching for the 'tab' character?

Awesome. How did you get it to find tabs, everytime I press the tab key it would go to the next textfield instead of searching for the 'tab' character?
I just copied and pasted.

I converted the tabs to spaces (it's a simple find and replace all in TextEdit) and that worked!
Ahh, yes. Windows and MSDOS do that. That brings back 20+ year old memories. And IIRC, some other system wanted commas as field delimiters, heh (RS Model2's ?).
I kind of thought the browser would take care of that between different systems. :confused:

Ahh, yes. Windows and MSDOS do that. That brings back 20+ year old memories. And IIRC, some other system wanted commas as field delimiters, heh (RS Model2's ?).
I kind of thought the browser would take care of that between different systems. :confused:

I tried replacing the original tabs with a new tab, and that didn't help. It must just be that CocoaNEC expects spaces?

So spaces + metric works... now how to convert all these existing ones to metric (and why aren't all you Canadians using metric to begin with! ;) )

that's just so easy! wow, never fails that I learn something new every day :D

OK. So now that I got one loaded, how do I rotate the model? I tried left clicking, right clicking, 2 finger clicking, holding down command, option, control, and space while clicking... I expected it to work similar to 4nec2 where you just click and drag a curved line and it rotates...

now how to convert all these existing ones to metric
Well, its only 2 mouse clicks and a save to convert in 4nec2. If you specify which model you want, Im sure most on this forum will convert it for you. :p

Edit:
For calculations, the GS card (Scale Structure Dimensions) that all models in inches use, is used to scale it back to meters. CocoaNEC should be able to read the GS card, so you have no problem doing the calculations. The card specification is in the Lawrence Livermore Laboratory necmanual3 I uploaded here :
http://www.wuala.com/300ohm/Documents/nec2manual3.pdf

For the other 2 parts:
http://www.wuala.com/300ohm/Documents/nec2manual1.pdf
http://www.wuala.com/300ohm/Documents/nec2manual2.pdf
Part 3 has the card specifications. Parts 1 and 2 have the extensive formulas that the NEC2 engine uses.

So now that I got one loaded, how do I rotate the model?
I think youre going to have to resort to reading his manual, heh.

I think youre going to have to resort to reading his manual, heh.

I was afraid of that ;) I should've done that before spending 15 minutes trying to figure out how to do it on my own. Turns out, you have to adjust the values on the bottom left for elevation and azimuth (you can see it in my screen shot). You can't use the mouse.

There were some recommended default settings to make in 4nec2 but I can't seem to find the post now. I have installed it on my new computer and I know they are off because the centipede shows negative gain even after i changed default imp from 50 to 75.

I think most of what youre looking for is here : http://www.digitalhome.ca/forum/showthread.php?t=107457
Also, if you have a relative recent processor and more than say a 1/2 gig of memory, change the NEC engine to Nec2dXS*.exe.
And in Folders > Notepad Editor change the location to C:\WINDOWS\SYSTEM32\NOTEPAD.EXE for windows XP.


I know they are off because the centipede shows negative gain even after i changed default imp from 50 to 75.
Should be 300.

That's right, antenna is on the other side of the matching transformer :)

Computer is a 3Ghz AMD quad core with 8Gb of ram and running w7-x64

Changing to 300 didn't fix it. When I sweep 470-700 in 5Mhz steps it shows a range of -20 to -2 for the forward gain. The pattern, if I do a vertical shows a pattern, but if I do horizontal, it's just a circle. Seems like there should be a pattern for ether and that vertical should be a side view and Horizontal a top down view.

In 4nec2's Gain plot, check the top left to see whether it is plotting FORWARD GAIN (Azimuth=90-deg)
or REVERSE GAIN (Azimuth=270-deg)....or something else. 4nec2 will start with the lowest frequency
and calculate the azimuth of maximum gain....this angle is what is thereafter plotted.

Some antennas won't have max gain in the FORWARD direction at the lowest freq....

You can force 4nec2 to plot FORWARD GAIN (at the expense of no Azimuthal Plot) as was discussed here:
http://www.digitalhome.ca/forum/showthread.php?p=981550

Keep playing with it....it really isn't that hard....and be sure to understand the options
in the fairly few number of "Card" types you'll find in posted 4nec2 files....
You can start with Geometry Editor (which doesn't support SYmbol Cards),
but to use the Optimizer/Sweeper, you'll need to convert over to variable SYmbols.

I had this working on my old system, but on the new, I still have something wrong. I found a few settings that didn't match, but they had no effect on this: http://24.255.17.209:2400/temp/Untitled.png

Ah, there's the problem: Elev=85 degrees instead of 0 degrees.
At 470 MHz the Max Gain beam must have been nearly overhead....or your entries were incorrect.
[After running the file, Max Gain beam at 470 MHz is NOT overhead....must have been your entries.]

I copy/pasted the file in your x0814 post and noticed you didn't include an "RP" statement, so
either you entered plot parameters manually....(or 4nec2 used whatever it had used before???)

I copied my "standard" set of FR & RP statements to the end of your file, instead of your FR statement.
It runs without problems. I pick and chose one FR and one RP statement and comment out the
remaining with an apostrophe at the beginning of each line:

' FR Freq Sweep choices in order of increasing calculation time (fm holl_ands):
' FR 0 0 0 0 602 0 ' Fixed Freq
FR 0 29 0 0 470 12 ' Freq Sweep 470-806 every 12 MHz - OLD UHF BAND
' FR 0 34 0 0 410 12 ' Freq Sweep 410-806 every 12 MHz - Even Wider Sweep
' FR 0 39 0 0 470 6 ' Freq Sweep 470-698 every 6 MHz - PREFERRED FOR UHF
' FR 0 77 0 0 470 3 ' Freq Sweep 470-698 every 3 MHz
' FR 0 153 0 0 470 1.5 ' Freq Sweep 470-698 every 1.5 MHz
' FR 0 71 0 0 300 10 ' Freq Sweep 300-1000 every 10 MHz - WIDEBAND SWEEP
' FR Hi-VHF choices:
' FR 0 15 0 0 174 3 ' Freq Sweep 174-216 every 3 MHz
' FR 0 29 0 0 174 1.5 ' Freq Sweep 174-216 every 1.5 MHz - PREFERRED
' FR 0 43 0 0 174 1 ' Freq Sweep 174-216 every 1 MHz - Hi-Rez
' FR 0 26 0 0 150 6 ' Freq Sweep 150-300 every 6 MHz - WIDEBAND SWEEP
' FR Lo-VHF choices:
' FR 0 35 0 0 54 1 ' Frequency Sweep every 1 MHz for Ch2-6
' FR 0 36 0 0 75 1 ' Frequency Sweep every 1 MHz for Ch5 + Ch6 + FM
' FR 0 28 0 0 54 6 ' Wide Freq Sweep every 6 MHz for Ch2-13
' FR 0 64 0 0 54 12 ' Super Wide Freq Sweep 54-810 every 12 MHz
' RP choices in order of increasing calculation time:
' RP 0 1 1 1510 90 90 1 1 0 0 ' 1D Gain toward 0-deg Azimuth - SIDE GAIN
' RP 0 1 1 1510 90 0 1 1 0 0 ' 1D Gain toward 90-deg Azimuth - FORWARD GAIN
' RP 0 1 1 1510 90 180 1 1 0 0 ' 1D Gain toward 270-deg Azimuth - REVERSE GAIN
' RP 0 1 37 1510 90 0 1 5 0 0 ' 2D (Left only) Azimuthal Gain Slice
RP 0 1 73 1510 90 0 1 5 0 0 ' 2D Azimuthal Gain Slice - PREFERRED
' RP 0 73 1 1510 90 0 5 1 0 0 ' 2D Elevation Gain Slice
' RP 0 73 73 1510 90 0 5 5 0 0 ' 3D Lower Hemisphere reveals antenna - Use Fixed Freq
' RP 0 285 73 1510 90 0 5 5 0 0 ' 3D Full Coverage obscures antenna - Use Fixed Freq
EN

Much better :D. Figured it was something simple. Don't know where it got that 85, that was the default setting with the new install

I keep getting error messages since Bokakobs centipede-2 file, now I cant run any nec files, regardless of size, its after I added the mesh - ive run much bigger files with no problems - so any ideas about these messages...

ive tried fewer segments, different settings, different engines, erased all.out files, reuploaded 4NEC2 all programs, restarted the computer, ahhggg :mad:

http://www.digitalhome.ca/forum/picture.php?albumid=355&pictureid=2031

You need to install 4nec2x. It installs after 4nec2