Carolina Windom Antenna

[cigarsmoker]

Hello Everyone.  I am new to this group and to this field in general.  I have begun to study space weather, propagation and their effect on radio waves to become a more knowledgeable and "better" ham radio operator.  After having read the instructions for Proplab 2 and Proplab 3 I have a question that I hope someone here can help me with.

I use (primarily) an antenna called a Carolina Windom which is 65 feet above ground.  It has two horizontal sections; one is 83 feet, the other is 182 feet.  The vertical radiator is at the junction of the two horizontal radiators and is 22 feet long and is connected via a balun.  At the low end of the vertical radiator (43 feet height) is a line isolator which connects to the feed line.  The quality of the ground (soil) is poor.

I can model this antenna using EZNEC but haven't a clue how to use HFANT in VOAcap.  I have looked at it, but there are no instructions with it or HELP section.  Do any of you know how I can get my antenna into Proplab 3?  Thanks in advance for your help.

Cigarsmoker

[Cary]

Hi Cigarsmoker. I'm certainly not as experienced as others may be with respect to EzNEC. However, I do know that 4nec2 can produce output radiation patterns that are largely in a text format compatible with Proplab3. Just a little editing of the text file may be required.

Using 4nec2, load your antenna project. Then under the Settings menu option, make certain that the ITSHf sub-option "Calculate output plot file" is checked. I also have the "Create 'point' input file" checked. Then use the "Calculate -> NEC-output-data" function to create a radiation pattern plot display. You can select the Far Field option. When that display appears, the "Plot -> 3D Plot" function will create a file that contains the radiation pattern you need.

The format will be something like this...

Code:

0 -90 -31.82
10 -90 -31.82
20 -90 -31.82
30 -90 -31.82
40 -90 -31.82
.
.
.
320 -90 -31.82
330 -90 -31.82
340 -90 -31.82
350 -90 -31.82
360 -90 -31.82

0 -80 -19.61
10 -80 -21.88
20 -80 -22.88
30 -80 -19.53
40 -80 -15.72
.
.
.

The first column represents the azimuth. The second column represents the elevation angle (you only want positive elevation angles) and the third column represents the radiation intensity (this example is in dBi - Proplab requires the radiation intensity in dBi.

Also, note that the radiation angle increments above are every 10 degrees. Proplab needs them to be every 1 degree, so change the settings when you Calculate.

Proplab3 is only interested in the maximum radiation intensities. That is, find the elevation angle that corresponds to the maximum azimuthal radiation intensity and use that. You will have to hand-edit the file so that it matches the format used by Proplab3. To see the format that is used, go into the Antennas folder and look at the format of the files there using a text editor like Notepad. There is a blank template file called BLANK.DAT that is empty. You can change it to fit your needs, then when you save it, use Save As... to change the filename to something like Windom.dat.

There is also a way that you can write ITSHF format files (the HFAnt format in VOACAP) using 4nec2, but I'm not entirely familiar with that process. If it will write true ITSHF format files, the utility included in Proplab3 should be able to convert it to an equivalent Proplab3 antenna file.

I hope this helps.

[cigarsmoker]

Cary

Thanks for the response and help.  I pulled up 4nec2 and with very little study was able to load my antenna.  I checked the output data against Eznec and they are close enough to suggest that I have loaded the data correctly.  Your instructions werte clear and easy enough that even I could follow.

Thanks again.

George Bennett