Antenna Modeling Uploads

[ghz24]

Thanks for the welcome Marconi.

Modeling in its primairy stage should be done in freespace...
As that is the only way to illuminate all the other influences.

Agree 100%
My last step is usually to add a variable," SY AGL=240" and add it to all the Z coordinates

Regarding those phase currents thingy..
I am more than willing to help...but what is it you do not understand ?

Is it the sigma 4 baskets and the "trick" employed to help the model show the basket elements in phase with the main radiator?

Does this?

heck there are those who do modeling...let say....with room for improvement.

Hey! I might resemble that remark
Even well meaning and conscientious modelers can overlook some important factor (like AGT tests) it's easy to miss things when you have lots of models and variations and you alter them considerably.
I hope for someone to point out where my models have room for improvement.
Even though I mostly use them to compare or answer a certain question.

This is my study model of the sigma 4 (in freespace)
It is not intended to be an exact model of any specific antenna (and probably needs a mast)

CM 11 meter cb by ghz24 (sigma 4)
CE
SY z=324	'driven element length
SY rh=108	'ring height
SY zp=12	'avoid segment errors
SY rsf=1	'changes ring diameter
GW	1	1	0	0	0	0	0	zp	0.17
GW	2	67	0	0	zp	0	0	z	0.05260011
GW	6	7	0	0	0	0	30*rsf	rh	0.05260011
GW	7	7	0	0	0	0	-30*rsf	rh	0.05260011
GW	8	7	0	0	0	-30*rsf	0	rh	0.05260011
GW	9	9	0	0	0	30*rsf	0	rh	0.05260011
GW	100	1	29.99994*rsf	0*rsf	0+rh	27.7163225*rsf	11.4804889*rsf	0+rh	0.05260011
GW	101	1	27.7163225*rsf	11.4804889*rsf	0+rh	21.2131466*rsf	21.2131466*rsf	0+rh	0.05260011
GW	102	1	21.2131466*rsf	21.2131466*rsf	0+rh	11.4804889*rsf	27.7163225*rsf	0+rh	0.05260011
GW	103	1	11.4804889*rsf	27.7163225*rsf	0+rh	0*rsf	29.99994*rsf	0+rh	0.05260011
GW	104	1	0*rsf	29.99994*rsf	0+rh	-11.480489*rsf	27.7163225*rsf	0+rh	0.05260011
GW	105	1	-11.480489*rsf	27.7163225*rsf	0+rh	-21.213147*rsf	21.2131466*rsf	0+rh	0.05260011
GW	106	1	-21.213147*rsf	21.2131466*rsf	0+rh	-27.716323*rsf	11.4804889*rsf	0+rh	0.05260011
GW	107	1	-27.716323*rsf	11.4804889*rsf	0+rh	-29.99994*rsf	0*rsf	0+rh	0.05260011
GW	108	1	-29.99994*rsf	0*rsf	0+rh	-27.716323*rsf	-11.480489*rsf	0+rh	0.05260011
GW	109	1	-27.716323*rsf	-11.480489*rsf	0+rh	-21.213147*rsf	-21.213147*rsf	0+rh	0.05260011
GW	110	1	-21.213147*rsf	-21.213147*rsf	0+rh	-11.480489*rsf	-27.716323*rsf	0+rh	0.05260011
GW	111	1	-11.480489*rsf	-27.716323*rsf	0+rh	0*rsf	-29.99994*rsf	0+rh	0.05260011
GW	112	1	0*rsf	-29.99994*rsf	0+rh	11.4804889*rsf	-27.716323*rsf	0+rh	0.05260011
GW	113	1	11.4804889*rsf	-27.716323*rsf	0+rh	21.2131466*rsf	-21.213147*rsf	0+rh	0.05260011
GW	114	1	21.2131466*rsf	-21.213147*rsf	0+rh	27.7163225*rsf	-11.480489*rsf	0+rh	0.05260011
GW	115	1	27.7163225*rsf	-11.480489*rsf	0+rh	29.99994*rsf	0*rsf	0+rh	0.05260011
GS	0	0	0.0254
GE	0
GN	-1
EK
EX	0	1	1	0	1	0	0
FR	0	0	0	0	27.18	0
EN

Not a really elegant model but I think it serves the purpose.
OH!I just opened a .ez file in notepad now I see why you cant just post the model like I did the one above. Is that a proprietary format?
And Marconi I don't think your efforts are in vain.

 

[Marconi]

24, in looking at your model of the Sigma4, I see it looks to be a close depiction of the antenna, but I understand nothing in the data entry screen view. However, the way I see it, this is probably similar to what other guy’s see when they first check out Eznec...it looks confusing to the uninformed mind. Maybe this is also how others see the Eznec model results that I've posted, as confusing simply because of a lack of understanding. This is where my "in vain" comment comes from.

For per review to be useful, I would think the audience would have to be well informed with the subject. Thus I don't think we can expect this th happen regarding the subject of modeling on this forum...except maybe from a very few, and it doesn't look to me like many of those will come forward either.

I might try copying all the code into my computer and see if I can get the model to at least work. Then I might be able to figure out something useful for my use of 4ne2. However, I think there are a lots of steps needed other than just entering in the data before you can run scans that produce results, so I might need some help there.

Let me play around with your model and I'll get back with some questions.

Henry, thanks for you attempt to work with me on the current phase issues using Eznec, but I never got your point when you started stretching out the red line current indicators using the elevator feature in the Antenna View, captioned as "Current."

 

[Henry HPSD]

in short...

open 4nec2 with your "favourite" sigma 4 model
1- calculate a far field pattern using for example the F7 function.
2- press F3 (or it migth have opende depending...)

3- Now in that F3 screen click on "currents"...

4- Below that indicator you will find several options
phase, currents...phase and currents etc etc.

5- if you futher investigate them you will find out the phase shift is there where the angle changes fast. That does not have to be at 0 degree.

Us people like to think "o" is a nice "spot" for a shift, but a circle doesnt understand what its "o degree" point is...we human have given it a starting point (0 degree)
Only the magnitude of the current in reference to time can provide insigth in where that shift is.
If you watch close you will find out the degree of angle will change fast (in time) and thats where your phase shift is.

Perhaps ...playing a bit with those current / phase ...current and phase thingy will give some insigth...

As i perfectly understand it is difficult to "get"especially from me ....English not beeing my "best" aspect hihi

Ehmm...that in time thingy...is just looking upwards the antenna..a current goes on the antenna and "stops" at the top.
There is a time differnce between those two. That time difference can be seen in the different segmentations, cause the vertical radiator is buildt up with segmentations on top of each other and there for representing a different "time"


You can get the model of GHZ24 to work.
Open 4nec2
Main window........go to settings:
press notepad edit.
click on that icoon "red book/pencile"
And copy past everything what is there into the "wires" window.
"save" and your there...

I havnt really looked at the model, but GHZ24 already said about agt etc...so im sure it is "close"...(if not spot on)



h

 

[Marconi]

Thanks Henry, this maybe just what I needed to get started using 4nec2. I've tried to use my Eznec file before in 4Ne2, but I never heard about or saw and example for using the Red book/pencile feature. Thanks for the tip.

 

[Marconi]

Kind regards,
Henry

ps havnt put that sigma 4 in cst yet...but will come..when time permitts...already 23.30 local again...so off to bed.

Don't worry Henry, I can't wait to see your CST results, but believe me I didn't hold my breath on your promise.

 

[Marconi]

in short...

open 4nec2 with your "favourite" sigma 4 model
1- calculate a far field pattern using for example the F7 function.
2- press F3 (or it migth have opende depending...)

3- Now in that F3 screen click on "currents"...

4- Below that indicator you will find several options
phase, currents...phase and currents etc etc.

5- if you futher investigate them you will find out the phase shift is there where the angle changes fast. That does not have to be at 0 degree.

Us people like to think "o" is a nice "spot" for a shift, but a circle doesnt understand what its "o degree" point is...we human have given it a starting point (0 degree)
Only the magnitude of the current in reference to time can provide insigth in where that shift is.
If you watch close you will find out the degree of angle will change fast (in time) and thats where your phase shift is.

Perhaps ...playing a bit with those current / phase ...current and phase thingy will give some insigth...

As i perfectly understand it is difficult to "get"especially from me ....English not beeing my "best" aspect hihi

Ehmm...that in time thingy...is just looking upwards the antenna..a current goes on the antenna and "stops" at the top.
There is a time differnce between those two. That time difference can be seen in the different segmentations, cause the vertical radiator is buildt up with segmentations on top of each other and there for representing a different "time"


You can get the model of GHZ24 to work.
Open 4nec2
Main window........go to settings:
press notepad edit.
click on that icoon "red book/pencile"
And copy past everything what is there into the "wires" window.
"save" and your there...

I haven't really looked at the model, but GHZ24 already said about agt etc...so im sure it is "close"...(if not spot on)

h

Henry, I either messed up or you failed to indicate some step in the bottom process for trying to get Eznec code into 4Nec2.


As a note: the window that opens up when I click on the icon: "red book/pencil" does not open a "wires window," it opens a window in notepad, and the file is a .txt file. If I'm right when I copy my code in Eznec I think I'm copying it as a text file also. Maybe I should do something different when I copy the wires code in Eznec.

ghz24, are you familiar with the procedure Henry is suggesting to me, so I can use my Eznec code with 4Nec2?

BTW, can I copy your code above as a text file here and then add it to the edit window that Henry suggested? If not, how would you email me a copy of your file and if I opened it would it open up my 4Nec2 program automatically?

 

[Henry HPSD]

Marconi,

All good things will happen, and i always have kept my promisse.
Time is the only limitating factor.

Anyway regarding the file.

I never mentioned it was "the" way to copy a eznec file into 4nec2.

I SAID you can get GHZ24 his file this way.

And yes, copy past is all that is needed.

The "notepad" window is similair to the wires window, though it contains far more information. But yes ...you are in the rigth window.

Let me know how you are getting along with that current phase thing.

PS...4nec2 should open any eznec file from the start you dont have to "change" them.

Kind regards,

Henry

 

[Marconi]

Marconi,

All good things will happen, and i always have kept my promisse.
Time is the only limitating factor.

Anyway regarding the file.

I never mentioned it was "the" way to copy a eznec file into 4nec2.

I SAID you can get GHZ24 his file this way.

And yes, copy past is all that is needed.

The "notepad" window is similair to the wires window, though it contains far more information. But yes ...you are in the rigth window.

Let me know how you are getting along with that current phase thing.

PS...4nec2 should open any eznec file from the start you dont have to "change" them.

Kind regards,

Henry

You're right Henry, I should have worded my response about your CST project a different way. Take your time.

I have given up on trying to understand what I see regarding current and phase using Eznec.

If I'm jumping the gun here Henry, just let me know. I know you are aware that some of the discussion about how the Sigma4/Vector works pertains to the current activity in the bottom portion of that antenna. I can only assume your CST project will be exploring these currents and phase in this area. If that is not the case, then can you tell us what you think you might be able to determine?

Regarding the 4Nec2 program. Some time ago I tried to transfer a simple Eznec file into 4Nec2, but I was not successful there either.

I don't have any problems sending Eznec files out, but for me this 4Nec2 product is difficult to get an idea for how it does things and I don't seem able to find an instruction manual. I looked at a video on YouTube and the guy sounds knowledgeable enough, but he seems to skip around too much and he make key strokes that I cannot follow. I know what he does makes sense to him, but I just can't quite follow him.

I also used a instruction video using An-Sof, and I picked up what they were saying and doing right away, but they probably did that video using a professional instructor.

I copied my Eznec Wires data using the Save feature in the Wires window. I pasted these wire values to the window you noted in 4Nec2. I saved this notepad screen with a name I wanted to work with, but when I tried to open it in the 4Nec2 main window...the file did not show up in the list.

I also noticed that all the files that did show up in that list were .nec files, and I'm pretty sure the file I copied was probably a .txt file.

I then tried to save the file again as an .nec file, but that didn't seem to work either. I looked around on my computer for both the files I saved, but I have no idea where they were saved to. The way it looked at the point in time that I did the save, I thought the file was going into the proper 4Nec2 folder.

This is where I'm stuck. Whatever the problem is Henry, I'll let you know if I'm able to figure it out.

Is it possible I can use an import/export feature to do what I wish to do? I'm sill curious how these models can be exchanged or email to others as well.

 

[Henry HPSD]

REgarding cst..
Well, i thougth you guys asked a couple times what the freespace gain would be ?
Just the "standard" things...and yes..im sure those currents will come along as well.
those were my initial thougths.


To "get" a eznec file into 4nec2:

open 4nec2.
Go to...open 4nec2 in.out file
Now at the bottum rigth corner, click on "TXT" and change that to .ez.
Use the adress line at the top to direct you to where ever your eznec files are....and your can "upload" your eznec files.



Regards,

Henry

 

[ghz24]

The code I posted can be pasted into a editor (notepad ect.) and either "save as" sigma4.nec or just save as a .txt and change the name to .nec instead of .txt save it in the 4nec2/models directory.
Start the 4nec2 program, go to the little folder below "file " this should bring up a browse for file window ,find/select the sigma4.nec file click open.

If you want to see and follow the code ( it's hard in notepad ) go to settings and select "nec editor " then "edit input" or F-6 then the code will become more clear I'm sure
If you click on a GW line (geometry wire) it should highlight the wire in the "geometry window"

The NEC editor (new) is even more "friendly" and more more powerful
The geometry editor I almost never use but others love it ( it wont allow variables) but can be useful in early stages of model building .

The same little folder icon under file cen open your .ez models just go to the bottom drop down and select all files or .ez before it will let you "see" .ez or other formats.Also allows conversion to .nec format.(edit ..OPPS I see Henry
HPSDalready said that.)
F-1 brings up and almost overly helpful help menu.
Hope that get's you started.

 

[davev8]

Back to the i10k with sloping radials i find this A comparison of 10 meter verticals using modeling
it seams optimum angel is 20 degrees for the radials
What's he mean on page 5 "dual 5/8 collinear"......is a collinear when you have sort of 2 vertical antenna in phase ?????

 

[The DB]

What's he mean on page 5 "dual 5/8 collinear"......is a collinear when you have sort of 2 vertical antenna in phase ?????

From wikipedia.

In telecommunications, a collinear (or co-linear) antenna array is an array of dipole antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear, that is they are located along a common line or axis.

A collinear array is usually mounted vertically, in order to increase overall gain and directivity in the horizontal direction. Theoretically, when stacking idealised lossless dipole antennas in such a fashion, doubling their number will, with proper phasing, produce double the gain, with an increase of 3.01 dB. In practice, the gain realised will be below this due to losses.

The DB

 

[W5LZ]

From the sound of his write-up, he is probably talking about a vertical array of two 5/8 waves.
There are a couple of things you should keep in mind. The first one is that he's using the 'demo' version of the modeling program so it's not going to be very accurate (as he states). And the other thing is that it's 'isotropic', meaning not 'real world' results or abilities. Don't get your hopes up too much. There's a lot he didn't say, so there would be some 'problems' with using the antenna exactly as it's illustrated.
- 'Doc

 

[Marconi]

From the sound of his write-up, he is probably talking about a vertical array of two 5/8 waves.
There are a couple of things you should keep in mind. The first one is that he's using the 'demo' version of the modeling program so it's not going to be very accurate (as he states). And the other thing is that it's 'isotropic', meaning not 'real world' results or abilities. Don't get your hopes up too much. There's a lot he didn't say, so there would be some 'problems' with using the antenna exactly as it's illustrated.
- 'Doc

'Doc, I agree wm5k was suggesting a vertical array of two 5/8 waves, but I'm not sure that is what is happening.

I've referenced this work before and I've noted that I had my doubts even though he claims his real world setup was successful. I've done models of the Imax with slanted radials before, but I never had the idea to make the radials 22.5' feet long. So, I decided to do a model of his idea at 27.205 mhz using less the 20 segments...similar to what he did using Eznec Demo.

I set the model at 40' feet to the hub, and added 4 x 22.5' slanted down radials at about 45* degrees. I did not get the exact same results, but here is what my model produced. I diddled with the model to see if I could get the results closer, but to no avail. I also added a 1' wire to the bottom of my model in order to get the feed point source close to the bottom like his model shows when using just 3 segments for a 22.5' long radiator. He also modeled at 28.5 mhz and that could be the difference. I think his work is also quite old and he may have been using a different Eznec too.

View attachment wm5k's Imax with .625 slanted radials..pdf

I'm in the process of adding a mast and the feed line to this model to see what Eznec predicts under those circumstances too, and this may suggest that the common mode currents produced by such out-of-phase currents and imbalance at the feed point will need to be effectively mitigated somehow as well.

I don't think this model suggested by nm5k will produce the results he discusses. Right off the bat I don't think we will see a collinear array or in phase results from this setup either, and you can see by the red line on the antenna the currents on the radials are quite heavy. In the past I've suggested that the radial currents for such a setup are going to be very heavy on the radials, and that may well dominate this antenna modification idea.

Here are the currents for this simple model: View attachment wm5k's Imax currents.pdf

You will note that the top portion of wire #2 shows a - sign for its phase and the rest of the antenna is a + sign. That means the top 1/2 wave of the radiator is not in phase with the rest of the antenna. This is not an array of two 5/8 wave in phase elements working together.

Note: sorry I got Mark's call nm5k wrong in this post and in some pdf files I've posted.

 

[davev8]

'Doc, I agree wm5k was suggesting a vertical array of two 5/8 waves, but I'm not sure that is what is happening.

I've referenced this work before and I've noted that I had my doubts even though he claims his real world setup was successful. I've done models of the Imax with slanted radials before, but I never had the idea to make the radials 22.5' feet long. So, I decided to do a model of his idea at 27.205 mhz using less the 20 segments...similar to what he did using Eznec Demo.

I set the model at 40' feet to the hub, and added 4 x 22.5' slanted down radials at about 45* degrees. I did not get the exact same results, but here is what my model produced. I diddled with the model to see if I could get the results closer, but to no avail. I also added a 1' wire to the bottom of my model in order to get the feed point source close to the bottom like his model shows when using just 3 segments for a 22.5' long radiator. He also modeled at 28.5 mhz and that could be the difference. I think his work is also quite old and he may have been using a different Eznec too.

View attachment 10186

I'm in the process of adding a mast and the feed line to this model to see what Eznec predicts under those circumstances too, and this may suggest that the common mode currents produced by such out-of-phase currents and imbalance at the feed point will need to be effectively mitigated somehow as well.

I don't think this model suggested by wm5k will produce the results he discusses. Right off the bat I don't think we will see a collinear array or in phase results from this setup either, and you can see by the red line on the antenna the currents on the radials are quite heavy. In the past I've suggested that the radial currents for such a setup are going to be very heavy on the radials, and that may well dominate this antenna modification idea.

Here are the currents for this simple model: View attachment 10187

You will note that the top portion of wire #2 shows a - sign for its phase and the rest of the antenna is a + sign. That means the top 1/2 wave of the radiator is not in phase with the rest of the antenna. This is not an array of two 5/8 wave in phase elements working together.

Reading page 4 again although he models at 45 degrees but hes say the gain increases until approx 20 degrees when its starts to fall of, so maybe 25 degrees is optermon ....id be interested if you did a model with radials at 25 degrees