-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
I-10K/Sockwave model first run
- Thread starter The DB
- Start date
Your video is very slick dB, and you did a very good job of presenting. Work on the camera focus a bit, and you may create some real interest in modeling for the members.
Good voice, confident, and well tuned at working the software. I saw a few o'heck situations and that might be expected, but you did a very good job of recovery...and I'm impressed.
Ole grampa had something unexpected happen in some of his videos...and I fumble and got completely off script at times. My big thing was being able to see what the camera saw as screen shots, but that was not a problem with you. Later if I get interested in videos again...I will be seeking you advise on your camera handling.
I like the 4Nec2 approach and slick reporting, but there are also lots of functional features in Eznec that are somewhat similar. Again, I love all the additional reporting and the optimizing is slick and fast. I see the idea about using formulas or code to expand control and build the model. I think something like the geometry entry is available in the Eznec Pro versions.
I love the optimizer and you can see me doing the same...one wire at a time.
You auto segmentation process is different from mine, and now I understand how you get past all the geometry and segment errors and don't have to worry about segments.
Does 4Nec2 produce data that shows the number of segments per wire when using the Auto Seg feature?
Without that info in a wire description from you how would I know the segment count per wire on a model you post?
DB, I couldn't read the details and I'm a little slow sometimes, but I think you made the radiator using a variable for wavelength x .625" inches, and the model you posted above has a radiator close to 20' feet long. This is way short for a 5/8 wave at 11 meters????
You suggested to us earlier this linear loaded idea was to electrically make the 5/8 wave look like a 3/4 wave...how do you do that with a shorter than 5/8 wave radiator or is the radiator also required to be short? According to my version of you model it shows to be terribly short of resonance with > -300 ohms of reactance and the resistive part at over 900 ohms?
I'll have some more questions I'm sure. Can you post the wires for the optimized model? That would save me some time, but for now...I'll be trying to adjust the space for the load.
What frequency did you use?
Good voice, confident, and well tuned at working the software. I saw a few o'heck situations and that might be expected, but you did a very good job of recovery...and I'm impressed.
Ole grampa had something unexpected happen in some of his videos...and I fumble and got completely off script at times. My big thing was being able to see what the camera saw as screen shots, but that was not a problem with you. Later if I get interested in videos again...I will be seeking you advise on your camera handling.
I like the 4Nec2 approach and slick reporting, but there are also lots of functional features in Eznec that are somewhat similar. Again, I love all the additional reporting and the optimizing is slick and fast. I see the idea about using formulas or code to expand control and build the model. I think something like the geometry entry is available in the Eznec Pro versions.
I love the optimizer and you can see me doing the same...one wire at a time.
You auto segmentation process is different from mine, and now I understand how you get past all the geometry and segment errors and don't have to worry about segments.
Does 4Nec2 produce data that shows the number of segments per wire when using the Auto Seg feature?
Without that info in a wire description from you how would I know the segment count per wire on a model you post?
DB, I couldn't read the details and I'm a little slow sometimes, but I think you made the radiator using a variable for wavelength x .625" inches, and the model you posted above has a radiator close to 20' feet long. This is way short for a 5/8 wave at 11 meters????
You suggested to us earlier this linear loaded idea was to electrically make the 5/8 wave look like a 3/4 wave...how do you do that with a shorter than 5/8 wave radiator or is the radiator also required to be short? According to my version of you model it shows to be terribly short of resonance with > -300 ohms of reactance and the resistive part at over 900 ohms?
I'll have some more questions I'm sure. Can you post the wires for the optimized model? That would save me some time, but for now...I'll be trying to adjust the space for the load.
What frequency did you use?
Last edited:
Below is my I-10K without a matching network in the model.
I present this first PDF file, because it tends to show a very little difference in the effects of changing the segment count in models without a physical match attached.
I'm not sure how this issue, if true, will effect one of your similar models...if you add matching using the matching feature in 4Nec2.
You will see in the second PDF, which we both have modeled, how the effects of adding a physical matching device might effect results for the pattern, gain, match, etc. At least this is what I've found.
I think this will help explain the segments issue that I commented on earlier...and I was surprised at what I saw in my models where I had added a physical match.
DB, I don't think this situation has anything to do with your Automatic Segment feature.
I will add the I-10K model with a matcher included in another post, and I think you will see my models fall apart if I reduce the segment count dramatically.
This is what I was a asking for when I requested you check your models of the I-10K with and without a matcher, and let me know if you see something similar...especially the skewing that you have reported with your models.
After I saw this I had the thought that the skewing you saw might be due to a segment issue, and maybe you were using too few segments.
I wasn't thinking about segments at the time, but I was surprised at this development on my end.
I present this first PDF file, because it tends to show a very little difference in the effects of changing the segment count in models without a physical match attached.
I'm not sure how this issue, if true, will effect one of your similar models...if you add matching using the matching feature in 4Nec2.
You will see in the second PDF, which we both have modeled, how the effects of adding a physical matching device might effect results for the pattern, gain, match, etc. At least this is what I've found.
I think this will help explain the segments issue that I commented on earlier...and I was surprised at what I saw in my models where I had added a physical match.
DB, I don't think this situation has anything to do with your Automatic Segment feature.
I will add the I-10K model with a matcher included in another post, and I think you will see my models fall apart if I reduce the segment count dramatically.
This is what I was a asking for when I requested you check your models of the I-10K with and without a matcher, and let me know if you see something similar...especially the skewing that you have reported with your models.
After I saw this I had the thought that the skewing you saw might be due to a segment issue, and maybe you were using too few segments.
I wasn't thinking about segments at the time, but I was surprised at this development on my end.
Last edited:
Actually, that wasn't a camera, I have a program that captured the video directly from my screen. That focus issue happened when I had an editor software remove the first and last part of the video and convert the rest to a Youtube compatible format. The original video didn't have it, however, the edited video did. Maybe I have something set wrong in that software, I don't recall it doing that when I played around with it the last time... Maybe I need to reinstall it fresh and set it up again, or perhaps convert the video to a more standard format before editing? I'll have to play around with it.
Thank you. The voice was picked up by a webcam microphone. I could have put video of me in a corner, but decided not to, at least not yet.
I know it tells me the total segments used with the model, it might have that information in the file that it drops to the Nec2 engine, which is a separate software. I'll have to look.
That is a good question.
I used the wavelength, and multiplied it be .625, which is decimal form for 5/8. Inches had nothing to do with it.
In my model the radiator goes from the top of the matching section to the tip, which is 5/8 wavelength above the radials. It is shortened some as it starts at the top of the matching section. That fact that it is actually shorter than 5/8 wavelengths is incidental. I can make that specific piece 5/8 wavelengths long if need be. I don't see it making a huge difference.
Yea sure, no problem. I even found a file that included the segment counts for you, along with the calculated lengths of said wires after the formulas so you don't have to calculate them yourself. I put the data in a hopefully more familiar layout, for easy reading... I know, it takes all the work out of it... In this one, the feed point is the second segment in wire 5. Also, this is in meters.
27.2 MHz
On your other post, the matching systems, namely the trombone like sections, are what is causing the skewing, I have made many models without the matching systems, and they have no skewing. The matching features built into Nec2 don't cause skewing either.
One thing I do need to correct, I have multiple times in the past said that .006 meters is about a half an inch, I was wrong, that is closer to a quarter inch.
The DB
A fix is always good when discovered. What are you using and is the editor a part of the program or an add-on?
Last edited:
DB, the PDF below shows the effects I see here by changing the segment count by a significant amount in a model. It just so happens that I used the Auto Segment feature in Eznec to demonstrate the effects, but this is not the problem...the problem is a model with too few segments being used is no-way-no going to be accurate.
You will also note that the length of the segments gets longer as the segment count gets smaller. I knew that segments were important and I figured this is likely what happens, but I didn't know it was this dramatic. When the segments vary substantially the currents are dramatically changed, and we can also see the change in the Antenna View as well. Just compare the red lines (the currents).
With this said, we don't see this much skewing when the matcher I added is missing from the models like I posted earlier with no matcher attached just to be clear.
So, I'm not too sure we should ever add a physical match to a model, else we risk the model breaking if we make a change in segments and maybe other settings will have similar effects as well.
What I ask you to do is confirm if this happens when you use the mathematical matching feature that comes with your 4Nec2? I don't know how to use the feature in Eznec or else I would check this out.
With these models compared to the previous models without the physical matcher added to the model...I hope I'm making my point on this clear for you. This has nothing to do with your use of the Auto Segmentation in 4Nec2 unless it is assigning to few segments...but looking at your new wires description that shows the accurate # of wires...I don't think you have any problem.
This is not a big deal, but maybe something to consider in our modeling.
You will also note that the length of the segments gets longer as the segment count gets smaller. I knew that segments were important and I figured this is likely what happens, but I didn't know it was this dramatic. When the segments vary substantially the currents are dramatically changed, and we can also see the change in the Antenna View as well. Just compare the red lines (the currents).
With this said, we don't see this much skewing when the matcher I added is missing from the models like I posted earlier with no matcher attached just to be clear.
So, I'm not too sure we should ever add a physical match to a model, else we risk the model breaking if we make a change in segments and maybe other settings will have similar effects as well.
What I ask you to do is confirm if this happens when you use the mathematical matching feature that comes with your 4Nec2? I don't know how to use the feature in Eznec or else I would check this out.
With these models compared to the previous models without the physical matcher added to the model...I hope I'm making my point on this clear for you. This has nothing to do with your use of the Auto Segmentation in 4Nec2 unless it is assigning to few segments...but looking at your new wires description that shows the accurate # of wires...I don't think you have any problem.
This is not a big deal, but maybe something to consider in our modeling.
Last edited:
I'm using software that was designed to make animation, but is also a very power video editing software, called Blender. It is free.
I would expect to few segments to have that effect, when you made these models did to check AGT on every one? I have found that changing the segment count, sometimes even by a small amount will have an effect on AGT.
You mean 4Nec2's ability to add a matching network to the model or are you referring to the optimizer feature that I used in the video above?
The DB
What you are saying does make sense, to few segments can screw up a model. I have also modified a model's segment count in the past to get it's AGT closer to 1, and from this I have learned that there is always one auto segmentation setting that will get me as close as possible to that point.
To test this I took the linear loaded model I made in the video and did some testing. I made 5 copies of this model, one to be run with 50 segments per half wavelength, the others have 40, 30, 20, and 10 segments per half wavelength. As I did in the video, I will modify the s variable, which is a separator between the elements of the linear loading section, so, in short, I will attempt to use the distance between the linear loading sections as a control for AGT. I am hoping the differences in this variable are relatively minor, but we will see. This is my biggest concern, if I have to significantly change this variable to maintain my AGT requirements I will have a model that will naturally have a different pattern.
I have two requirements for each of these models, I want to be able to tune SWR to be as low as possible, I will use the optimizer for that, and I want to keep AGT as close to one as I can. preferably between .99 and 1.01. This range is to make sure we are comparing apples to apples.
Taking a look at said S variable:
50 segments, 0.3
40 segments, 0.36
30 segments, 0.5
20 segments, 0.6
10 segments, 1.0
This is what it took to maintain the AGT requirements I put on this project. The 50 segments is the baseline, 40 segments is near as makes not real difference. At 30 and 20 segments, we are beginning to push the limits, and the 10 segments model is beyond what I would consider acceptable in any way, it is over three times the difference in length, and this is applied to the antenna model three times. I will run through the results, but I won't consider the 10 segments per half wavelength model accurate, it simply required to much of a modification of the antenna to be achieved.
The SWR results for these models is as follows:
50 segments, 1.32 SWR
40 segments, 1.32 SWR
30 segments, 1.33 SWR
20 segments, 1.35 SWR
10 segments, 1.49 SWR
It seems the ability to tune SWR is pretty stable, at least to a point. All of these models are also close to resonance.
I'm not going to show them here, but the SWR curves are also very similar, except the 10 segments per half wavelength model the curve has shifted up to a higher SWR compared to the others.
Now for the pattern comparisons...
Most of the patterns are consistent, although again the 10 segment per half wavelength model, as expected, is the most different. The problem is, the big change I needed to maintain a reasonable AGT is more likely to be responsible for this than the segment count itself.
I am going to have to rethink how to do this type of testing to rule out said types of changes. However, based on my experiences with modeling, I am reasonably certain your low segment count causing problems idea has merit, there has to be a minimum reliable segment count. The data above shows that as you go up in segments, the results change less and less. It might me interesting to do the same thing with more segments as well, up to 100 segments per half wavelength, to see if everything stabilizes further, or if other problems are created. That will have to wait, however.
The DB
To test this I took the linear loaded model I made in the video and did some testing. I made 5 copies of this model, one to be run with 50 segments per half wavelength, the others have 40, 30, 20, and 10 segments per half wavelength. As I did in the video, I will modify the s variable, which is a separator between the elements of the linear loading section, so, in short, I will attempt to use the distance between the linear loading sections as a control for AGT. I am hoping the differences in this variable are relatively minor, but we will see. This is my biggest concern, if I have to significantly change this variable to maintain my AGT requirements I will have a model that will naturally have a different pattern.
I have two requirements for each of these models, I want to be able to tune SWR to be as low as possible, I will use the optimizer for that, and I want to keep AGT as close to one as I can. preferably between .99 and 1.01. This range is to make sure we are comparing apples to apples.
Taking a look at said S variable:
50 segments, 0.3
40 segments, 0.36
30 segments, 0.5
20 segments, 0.6
10 segments, 1.0
This is what it took to maintain the AGT requirements I put on this project. The 50 segments is the baseline, 40 segments is near as makes not real difference. At 30 and 20 segments, we are beginning to push the limits, and the 10 segments model is beyond what I would consider acceptable in any way, it is over three times the difference in length, and this is applied to the antenna model three times. I will run through the results, but I won't consider the 10 segments per half wavelength model accurate, it simply required to much of a modification of the antenna to be achieved.
The SWR results for these models is as follows:
50 segments, 1.32 SWR
40 segments, 1.32 SWR
30 segments, 1.33 SWR
20 segments, 1.35 SWR
10 segments, 1.49 SWR
It seems the ability to tune SWR is pretty stable, at least to a point. All of these models are also close to resonance.
I'm not going to show them here, but the SWR curves are also very similar, except the 10 segments per half wavelength model the curve has shifted up to a higher SWR compared to the others.
Now for the pattern comparisons...
Most of the patterns are consistent, although again the 10 segment per half wavelength model, as expected, is the most different. The problem is, the big change I needed to maintain a reasonable AGT is more likely to be responsible for this than the segment count itself.
I am going to have to rethink how to do this type of testing to rule out said types of changes. However, based on my experiences with modeling, I am reasonably certain your low segment count causing problems idea has merit, there has to be a minimum reliable segment count. The data above shows that as you go up in segments, the results change less and less. It might me interesting to do the same thing with more segments as well, up to 100 segments per half wavelength, to see if everything stabilizes further, or if other problems are created. That will have to wait, however.
The DB
I will check Blender out. I tried doing screen capture video with my Logitech, but tracking that was a beast. Your video is slick and is just what is needed to capture my desktop view for a video.
No, I thought about it, but first I wanted to see if you could confirm my claims. I wasn't sure it was just the way I modeled my I-10k adding a physical matcher to the mix. Your suggestion for checking the AVG is probably the best way to test our segment decisions.
Yes, using the matching network idea instead of adding the physical matcher, like I did. This is not about using the optimizer.
When I first tried adding the trombone matcher to my I-10K model I thought doing so would possibly show better results and maybe be more accurate. Now, I don't think adding a physical matcher to a model is a good idea. However, I would still like to know what you find, in this regard, using the 4Nec2 software matching feature.
I take you word for this one. I haven't tried this with Free Space models yet. I also notice, and maybe you can see this in the models I just posted, that as the segment count get lower in numbers the red "O" indicating the Feed Point also changes in relationship to it normally assigned location, and IMO this too may be a play in what we see here.
I agree, so for me this conversation has shed more light on my approach to modeling, and when I learn something new...it is a good day.
Can you optimize using AVG as a goal for success?
DB, I have to start modeling using 4Nec2, for me to do something similar I have to use trial and error, write down the results as I make changes, and then try and analyze what the data shows.
I'm not in the weeds with my math skills, but I'm not a math man either. Do you think I can master the seeming complicated code to setup the optimizer and use the geometry editor that you use?
Like I said above, if you check the FP out as noted on my Antenna view, and look for the segments set at 10/.50w vs. 50/.50w you will notice the FP is not anywhere near the point it was set at on the antenna compared to the model I originally made using my segment scheme of approximately 3" inches per segment.
The 10/.50w ratio above would generate a segment length of about 43.2" inches per segment, and the 50/.50w would be 8.64" inches per segment, while my model is set at about 3" inches per segment.
Now for the pattern comparisons...
Here are my overlays of my models with and without the matcher added that shows me the difference to be noted when we add a physical match to the model, which IMO is no-way-no. I think if you expand you image above you will see my models compared to your models.
Most of the patterns are consistent, although again the 10 segment per half wavelength model, as expected, is the most different. The problem is, the big change I needed to maintain a reasonable AGT is more likely to be responsible for this than the segment count itself.
Your work here suggest what I recall reading in the Eznec manual where Roy Lewallen posed below. He told us that segments were very important to the success of a model. You will also note some similar words in the manual that you suggested above.
I agree
Last edited:
You guys have gone deep into antenna modeling here and it truly is something for others to appreciate if they so wish to. I am truly glad to see this thread continue the way it has and all I can say is WOW!! Good work gents and keep at it!! Not everyday do we get all this kind of info. Just goes to show that with some proper sharing of thoughts and ideas how far and how much can and has been achieved. Well done to both of you guys and hope to see more out of this thread. It truly does open your eyes to how things actually work and the way they work. Keep at it!!
DB, I made a mistake in my post above comparing our overlays. I think I posted my 2 overlays in the window of your overlay image by mistake. You may get down there and not see what I added as a last minute edit, so I think you might have to expand your original image to see what I added. If I have time before the clock runs on editing the post...I will try and fix it.
The screen capture software is OBS, or Open Broadcaster Software. That saved in a non-standard (or at least unfamiliar to me) video format. Blender was used to edit said video and convert it to a more standard format. Blender took some playing with to make it work that way as it is intended as an animation rendering software. If you don't want to edit, only convert, VLC can do that for you.
I will have to do this. I don't normally use said matching networks anymore as they more often than not seem to be made out of ideal or near idea components, and I'm reasonable certain that does not simulate the real world as I want it to, hence my experimenting with physical matching networks.
I am still working with them, I want to make at least a Maco ring style matching network that I can tune, at lest to a point, I am concerned about the tap points, their won't be as many as there are on the actual antennas. I also don't have the capacitance of the hidden, if you will, built in capacitor on that antenna design. I don't think this capacitor would be required to make a functioning model, but it would be useful in comparing an antenna design with and without said capacitor.
I also want to expand the I-10K/Shockwave model some. I want to give the ends of the matching section more of a curve rather than just be straight up and down. I think that will lessen the skewing some, but not eliminate it. Weather or not the skewing exists on the actual model isn't in question to me, the question is how much. Not that anyone would notice the small amount of skewing most of the models are showing.
That wasn't an issue in my case. The models I made all had the feed point centered on said wire. That being said, adding more segments to said wire as I had to lengthen it on the models with fewer segments would have an effect as well.
Unfortunately no. I have the options of SWR, Gain, Front to Back, Front to Rear, R, X, and Efficiency as options.
While I use math in many of my models, it isn't always required, but when you need it you need it. It is more or less used in what I call the planning stage, I plan the model out so the wire entry later will be as simple as possible, and modifiable as possible as well. You could make a model how you are used to, then modify it afterwards to include said functionality. That is how I started modeling that way, and what you saw in the video is an evolution of that. I'm happy to help you learn my methods if you think they will benefit you. I am also happy to help with any aspect of 4Nec2.
One thing that might help you, you can make an initial model in EZNec and import it into 4Nec2. That might be a good starting point to learning 4Nec2, seeing how a familiar environment applies to another environment you want to learn...
The DB
Can you email Arie Voors? I would ask him about this matching issue. At worst he can say he can't mentor his product, like Roy does. I would like to know the answer to this question, because it may nix my desire to learn how to match.
I have a V58 model on my old computer, but I haven't transferred all my files yet, so it is not available. I could not figure out how to isolate the radiator inside the base mounting tube or add a capacitor. My V58 model with the matcher is not a good model.
If you think that will make a difference, then try making a coil with the same diameter you need to match the end of the trombone tuner, and then remove all the wires you don't need leaving an arch. Then move the wires and attach. That is the way I might try that.
It may sound easy to you my friend.
Have you modeled a Penetrator 500? If so, did you create the High Gain raised radial mounting bracket for the antenna model? I see this design showing a very good gain, but the pattern is skewed somewhat, and I'm not sure the gain or this model are accurate. It does however support what I've heard from folks for years however...this was the best of the best. But another old saying is, if it is too good to be true...then it is probably not so good...or something like that.
BTW, I just model a Antenna Specialists Super Magnum antenna, and it too is showing remarkable results with the old HG mounting bracket included in the model. However, I see a terrible match with this one and maybe that adds to the effect of higher gain that I see...just not sure.
Last edited: