I-10K/Sockwave model first run

[Marconi]

I haven't seen or heard of anything related to that in 4NEC2. When I tell it where a feed point is it just marks a segment as a feed point. To be fair, I haven't really looked either.

I think we've talked about this before, I posted a PDF file of a portion of the 4Nec2 manual below on the subject.

It is possible that that is a feature you have access to that I do not.

No, but your application may be more physical like you do with a single feed point. BTW a split feed point is still a single feed point...it just covers two wire and the wire junction and get the source closer to the end of a wire. Pretty simple process, if you think about it, else this old man would have never been able to figure it all out.

Maybe I've tried to discuss this before with Donald instead of with you. I just don't remember for sure.

That would potentially be a difference we both had with your model that we may have to account for in the future as, as far as I know, I have to have a segment in the spot of the feed point.

I do too, and Roy told me a story about this once in the beginning...as I had questions trying to get Eznec to work.

The optimization feature also uses those variables we talked about above. It does seem to be a bit touchy about them though.

Just following more rules in changing the physical antenna automatically which can be a difficult task at best to maneuver.

I still do it the old fashion way, but you still have to know what you can do and what you can't do. BTW we found out the circuit we used has to be very thin wire are you can develop Geometry and Segment errors and warnings...just like you found earlier.

If you need help ask. Just be aware that when you say apple I might hear orange, I'll keep that in mind as well.

Fair enough.

I just did that real quick. The pattern looks pretty much the same, the tune still meets my requirements, but the gain dropped some, it now has 4.94 dBi gain.

Like I said earlier...I spent the better part of a day and evening on my end, and I still don't fully understand it. BTW the PDF file below is missing a page, so you will have to check these Split Source instructions out in your manual. Sorry, I thought I got it all.

 

[Marconi]

I downloaded eznec recently but haven't really learned to use it effectively yet. Hats off to the guys that take the time and post their results here

543 I must have missed your post. If you have any questions or would like me to email you a simple 1/4 wave or 1/2 wave model to get started using the Eznec Demo version...just let me know. But DB is correct, in order to get a version of Eznec that will really function for most CB antennas...you will have to spend some money and DB is correct 4Nec2 is free and is feature rich.

I don't know about you or DB, but the hardest thing, for me, about modeling was figuring out what the wires screen did and how antenna dimensions were distributed over the spreadsheet editor called "Wires" on the Main Screen which controls all aspects of the program.

A member sent me a simple model of a 1/4 wave with a horizontal ground plane and from his Wires screen (spread sheet editor) I saw the light, and my learning curve has continued since then. If I can help...then go for it.

There are also things I can do that I haven't seen done with EZNEC, for example, the capacitor included on the imax antenna model in another thread...

DB, I would be interested in a simple discussion about how you did the capacitor too if and when you get some time.

I had considered making a video series showing how I make models, how to test for accuracy, what to watch out for, ect. and posting it to youtube. The idea was to help others while shoring up what I think I know about modeling... Unfortunately I really haven't had the time...

I tried making an Eznec video of "Ole Grampa doing his thing" a while back and it was not as easy and simple as it would seem. DB, the videos I did on comparing signals was ruff enough, but I encourage you though.

If you have any questions with either of these programs, don't hesitate to ask. I'm willing to help you learn, and I'm sure Eddie is as well.

543, of course I will help if I can.

 

[Marconi]

DB, after I got my I-10K with the trombone working in the model and producing 1.36:1, SWR...I decide to make a comparison between the patterns to see what the differences were...between the models with and without matching.

The first model shows the I-10K with a match, and the second model is without the match. The antenna view, and the patterns also have the currents turned on. The models are also set to show the Vertical, Horizontal, and Total RF field and the indication of some Horizontal RF produced for the I-10K model...was a surprise to me and this may be significant to the antennas performance. At least it is something to consider. I also notice a smaller Horizontal contribution in the pattern for the model without the matcher included. Go figure!

At the end I also added two pattern overlays, with one then the other activated, to show us the maximum gain, angle, and pattern shape differences. The trombone does look to have a positive effect for the model with a matcher included. It shows a little better gain, and definitely includes some horizontal RF in the pattern which could be of benefit in the real world use.

I can't be sure, but these differences may have some beneficial effects on performance that could be detectable maybe. The model with the matcher also shows about 1/2 as much current flowing on the mast for some unknown reason.

Both models produce very similar patterns with about the same maximum gain, which is good, but the no-match model shows about double the current flowing on the mast, which is not so good.

I have made other models with their physical matching device added to the model, but the matchers were all physically much smaller than the trombone matcher. So, IMO the I-10K's matcher may really provide a little benefit over other similar CB 5/8 wave antennas...like Bob85 reports to us using his I-10K.

So I figure modeling most CB antennas without including the physical matching device probably will shows us about the same information about gain and angle performance. If the antenna needs a matcher however, you will either need to model the electrical matching provide as a feature in the software, or do without SWR and Bandwidth information.

 

[The DB]

The first model shows the I-10K with a match, and the second model is without the match. The antenna view, and the patterns also have the currents turned on. The models are also set to show the Vertical, Horizontal, and Total RF field and the indication of some Horizontal RF produced for the I-10K model...was a surprise to me and this may be significant to the antennas performance. At least it is something to consider. I also notice a smaller Horizontal contribution in the pattern for the model without the matcher included. Go figure!

I've seen the same in my model, and when I played with your model I've seen the same thing even with the errors in said model. The more currents flowing on said section the stronger the horizontal component seems to be. If there is no matcher, everything that is horizontal is in balance so there is little to no horizontal radiation.

At the end I also added two pattern overlays, with one then the other activated, to show us the maximum gain, angle, and pattern shape differences. The trombone does look to have a positive effect for the model with a matcher included. It shows a little better gain, and definitely includes some horizontal RF in the pattern which could be of benefit in the real world use.

I haven't looked at it closely yet, but I saw the same effect, the trombone matching section increased gain slightly in my models.

I can't be sure, but these differences may have some beneficial effects on performance that could be detectable maybe. The model with the matcher also shows about 1/2 as much current flowing on the mast for some unknown reason.

This is something I haven't noticed, as of yet, but then I keep finding myself doing other things with this and other models... It is still on my list of things to do.

I have made other models with their physical matching device added to the model, but the matchers were all physically much smaller than the trombone matcher. So, IMO the I-10K's matcher may really provide a little benefit over other similar CB 5/8 wave antennas...like Bob85 reports to us using his I-10K.

A direct comparison between antennas including matching system is what I wanted to find out, and part of why I started making the i-10k model. I figured that with what I know, of all of them it would be the easiest for me to build and tune...

So I figure modeling most CB antennas without including the physical matching device probably will shows us about the same information about gain and angle performance. If the antenna needs a matcher however, you will either need to model the electrical matching provide as a feature in the software, or do without SWR and Bandwidth information.

While there is a difference between modeling with and without a matching section, I have yet to see a big difference, unless I intentionally added extra loss using the matching feature in 4Nec2. From what I understand, that feature uses ideal components, which will show less loss than what would normally happen in reality. I actually tried to make a model of a half wavelength antenna that had the bandwidth of an a99, I never succeeded, and even with half of the bandwidth gain was down by well over 3 dB. I think that was a bit extreme based on people's actual comparison reports. Further, said matching devices also seem to affect the bandwidth you get from them. I can't just plug one in and assume its results are close unless I know a matching device was made based on said data. Unfortunately it isn't really useful for most antennas, it seems to be more meant for making such tuning systems for antennas than antenna comparison use, which is more or less why I took up modeling to begin with.

DB, I would be interested in a simple discussion about how you did the capacitor too if and when you get some time.

Sure.


The DB

 

[543_Dallas]

543 I must have missed your post. If you have any questions or would like me to email you a simple 1/4 wave or 1/2 wave model to get started using the Eznec Demo version...just let me know. But DB is correct, in order to get a version of Eznec that will really function for most CB antennas...you will have to spend some money and DB is correct 4Nec2 is free and is feature rich.

I don't know about you or DB, but the hardest thing, for me, about modeling was figuring out what the wires screen did and how antenna dimensions were distributed over the spreadsheet editor called "Wires" on the Main Screen which controls all aspects of the program.

A member sent me a simple model of a 1/4 wave with a horizontal ground plane and from his Wires screen (spread sheet editor) I saw the light, and my learning curve has continued since then. If I can help...then go for it.



DB, I would be interested in a simple discussion about how you did the capacitor too if and when you get some time.



I tried making an Eznec video of "Ole Grampa doing his thing" a while back and it was not as easy and simple as it would seem. DB, the videos I did on comparing signals was ruff enough, but I encourage you though.



543, of course I will help if I can.

The wires screen is where I am now. I downloaded eznec a few weeks ago but haven't spent much time with it. Thank you both for the tips and support.

 

[Marconi]

DB, after I got my I-10K with the trombone working in the model and producing 1.36:1, SWR...I decide to make a comparison between the patterns to see what the differences were...between the models with and without matching.

I posted these comments in an earlier post above in this thread, but to make a point about why I ever attempted to add the trombone tuner to the model some time back. So, I think I should explain further.

The point was to see if adding the physical matching device to the model would make a difference. In the past Jay, the developer of the antenna and his self proclaimed sidekick Master Chief, both use to express the superior benefits for the trombone tuner, and that raising the radiator well above the rest of the antenna produced better working results.

So, I wanted to see if they were right and would a model show any difference compared to other 5/8 wave. Lots of folks back then and even now proclaim a 5/8 wave is a 5/8 wave and nothing more...when compared at equal heights above ground.

Well I haven't got my model to produce a perfect match yet, like DB has, but it is close at 1.355 SWR compared to the antenna without any matching device added...and such a model for me shows 18.885 SWR. That is a lot of difference, so the matcher does work.

Below are the two Source Data reports for my models.





So, in case you missed this important point...you can get an idea here...exactly what the difference to including or not...a matcher with your modeling.

How say you?

 

[Marconi]

DB, here are your models with the trombone matcher included in the model. What is the difference I see between the source location on these two models, and which one is producing the perfect match you talked about earlier?

I want to try and get my I-10K model to showing as good of match as you posted earlier. Can you help me here?

 

[The DB]

View attachment 19027
DB, here are your models with the trombone matcher included in the model. What is the difference I see between the source location on these two models, and which one is producing the perfect match you talked about earlier?

I want to try and get my I-10K model to showing as good of match as you posted earlier. Can you help me here?

The first one is a trombone matched antenna, the second one looks like a trombone matched antenna, but in fact is not. What appears to be a trombone style matching system is actually a horizontal linear loading section on a vertical antenna. It is one of three models I made, another model looks like this...

That antenna predated my efforts to make a tapped trombone matching section that I was/am talking about in this thread. I was experimenting with linear loading with 5/8 wavelength antennas, essentially using that as a loading method to get an electrical 3/4 wavelength antenna, which should combine with 1/4 wavelength radials to produce a low R at resonance, therefore having a naturally low SWR. I did not get it to a perfect match, but using nothing but a linear loading section I got SWR down to 1.2:1. The trombone matching system does, however, outperform that model, if only slightly, it is more efficient according to 4Nec2.

In that case, linear loading essentially has a similar effect as using a loading coil for loading, at least so far as it makes a shorter antenna act like a longer antenna. It was an experiment, and it actually worked better than I expected it to. I modified that model to make the tapped trombone model as shown in your image above it, so if anything my experimenting with a trombone style matching system in a 5/8 wavelength antenna model is an evolution of my playing with linear loading in a 5/8 wavelength antenna model.

The trombone match I have has a tapped element between the bottom and center of the trombone sections, I can also adjust either side of the trombone independently using the variables I talked about above. I have a variable for each side's length, and it is more a matter of changing them a little at a time until I get the match that I am looking for. As I recall offhand, one side has more of an effect on where the SWR minimum was, whole the other side had more of an effect on how deep the low SWR point was.


The DB

 

[Marconi]

As I recall offhand, one side has more of an effect on where the SWR minimum was, whole the other side had more of an effect on how deep the low SWR point was.

The I-10K manual goes into something similar. Jay notes for these effects in the 1st PDF file below.

I haven't seen or heard of anything related to that in 4NEC2. When I tell it where a feed point is it just marks a segment as a feed point. To be fair, I haven't really looked either. It is possible that that is a feature you have access to that I do not. That would potentially be a difference we both had with your model that we may have to account for in the future as, as far as I know, I have to have a segment in the spot of the feed point.

With Eznec I select "source" and a window opens and I enter the wire # and the wire end as a % of the segments for the wire, and the software figures out the segment to place the Feed Point. Not sure, but to me your source setup sounds similar. I though you said earlier you had to assign the location for center conductor and the ground to locate your Feed Point with 4Nec2. Do you have two methods of inserting the source?

That being said, I have never used the taper feature of 4Nec2. I never felt the need to use it.

Before I learned that Eznec produces unreliable results using taper, I made my models with taper, because I felt it was just more accurate to model the antenna to its actual physical dimensions. After I learned better that taper was no way no I started making my wires without any taper. I started estimating my tubing dimensions based on the real dimensions I was able to find. I try to get close to what that might be for my models, but sometimes I have to just guess.

I've read about software that does make an effort to solve this issue, but I use an old fashion way of trying to determine how close my estimate is...trial and error. Sometimes, if I can find some claims data from a well documented antenna manual, and/or info noted elsewhere as well and I don't need to match the antenna...I can the test the model for match and bandwidth and get close enough for government work.

I also hear as long as you get close in you estimate of the wire size distribution along the length of your wire...it just doesn't make much difference in the real world vs. modeling. This is sorta' like I'm finding, in general, adding the physical match to a model...it just don't matter that much. I think your modeling using the matching features in 4Nec2, also show similar results for the performance indicators, gain, and angle. So when we see a model that does not include the physical match or the mathematical equivalent match in a model...the difference is still minimal.

I can say the 4Nec2 version of this uses some formula to set the entire length of an element to a single diameter that will act like the taper. Through my own experimenting, I don't see this making a significant difference, although now that I am including things like the material the antenna was made from, and beginning to include matching circuits that are actually tunable while on the antenna, and other ideas I might come up with to increase accuracy, this may one day change.

Eznec is not that slick to determine what tubing diameter the model needs...if this is what you are telling me. Like I said above, I've read about software that does do what I think you describe however.

That is a feature built into Nec2 that 4Nec2 takes advantage of. It is actually a pretty powerful feature once you figure it out, as I used it in the Vector model above to define the ring radius on both the X and Y axis, but I included a formula to calculate 12 other points on the ring. If I want a ring of 19 inches, it gives me a circle of 16 points and the wires between them for 19 inches.

Well DB, Eznec will produce all of the wires needed to produce a circle or a coil, etc, but I have to enter all the correct data noted for the physical antenna into the screen feature for the software using straight wires to try and duplicate a circle or an arc. I also have to describe the location for such devices such as the Sigma3/Vector ring for the radial cone design attaching right at the top of the 3-4 radials on the antenna. Eznec also works similar and automatically for radials, coils, and a helix form.

Personally, I am thankful I was able to figure out the use of these features using Eznec. Looking back I could say I'm amazed I understand these uses at all. I just haven't figured out the matching feature yet...it is like a mental block, with me maybe.

If I want a different sized ring I just change the 19 inches to whatever radius I want to use. With this use, think of it as a means of automating a process that I would have to calculate by hand every time I wanted to change the diameter of said ring. That is what I have used it for in the past and I still use the feature mainly the same today.

I figure now you're are talking about the optimizing feature using 4Nec2. Eznec will not do that directly, but there is software available on the Internet...what claims to use Eznec data descriptions, and build macro's for automatic optimizing the model.

I still can't get my I-10K model, with the trombone added, working to produce the match you're getting. I also am not getting a good Average Gain value for my model in Free Space either. I can find 50 ohms on the T1 end of the tuner, and it shows a perfect match at resonance, but the AG is still off by too much.

How say you?

 

[Marconi]

DB, you also talked about Linear Loading, but I don't know much if anything about the subject, so I didn't respond to you about that.

However, here is what the Eznec manual says it that regard in PDF file below. The primary point I take away from these words is: ...that Eznec Pro with Nec 4 engine can deal with LL'ing, but not using Nec2.

DB, is this Linear Loading idea similar to what Henry and others do with their OWA designed Yagi beam setups?

Click here for Henry's webpage: http://www.hpsd.nl/f-yagi/11-5el-owa-yagi

 

[The DB]

DB, you also talked about Linear Loading, but I don't know much if anything about the subject, so I didn't respond on the subject.

However, here is what the Eznec manual says it that regard. The primary point I take away from these words is: ...that Eznec Pro with Nec 4 engine can deal with LL'ing, but not using Nec2.

DB, is this Linear Loading idea similar to what Henry and others do with their OWA designed Yagi beam setups? http://www.hpsd.nl/f-yagi/11-5el-owa-yagi

The OWA design is a completely different idea that uses a parasitic element for matching and to achieve a wide bandwidth. Linear loading does not use a parasitic element.

Linear loading is a loading method generally used with horizontal antennas, but can also work with vertical antennas. Essentially, part of the antenna is folded back onto itself. With a horizontal dipole antenna the antenna goes out from the feed point to the end of the antenna and then is folded back towards the feed point, kind of like a folded dipole only the parts folded back towards the feed point are not connected to each other. The area going from the tip back towards the feed point is the linear loading. This method is also used in yagi antennas for both the radiating element and the other elements. If you need to make the antenna shorter still, you can fold said elements again and head back towards the tip of the antenna.

The ARRL Antenna Book, 22'nd edition says that this form of loading is more efficient than either a coil based load or using a cap hat. It is also something that I didn't really understand, so I was playing with it in modeling. I am aware of elements being so close together causing problems, so I used elements that were farther apart. It still works, although the further apart the elements the more skewing said loading creates in a model. The horizontal linear loaded section model was an attempt to limit the skewing of the model as much as possible, although, like with the I-10K/Shockwave model, it did add a horizontal component.

On an additional note, I also found that for every amount of shortening, there seems to be an optimum amount of separation to use for efficiency, and getting the wires either closer or further from that point affects efficiency to some degree.

I can see how on a yagi such small errors will add up, however, I was not using linear loading on a yagi antenna. I have, however, considered paying the $300 to get Nec4... As of yet I haven't seen the need to drop that much money on it... Should I decide to I can simply drop it into a folder in 4Nec2, and change a setting, and I am working with Nec4.


The DB

 

[The DB]

With Eznec I select "source" and a window opens and I enter the wire # and the wire end as a % of the segments for the wire, and the software figures out the segment to place the Feed Point. Not sure, but to me your source setup sounds similar. I though you said earlier you had to assign the location for center conductor and the ground to locate your Feed Point with 4Nec2. Do you have two methods of inserting the source?

With 4Nec2, I say which wire and segment to use. I don't have a % of the segments option. However, if I am using auto segmentation and that happens to change the total segments on said wire, the location of the feed point does not change.

Before I learned that Eznec produces unreliable results using taper, I made my models with taper, because I felt it was just more accurate to model the antenna to its actual physical dimensions. After I learned better that taper was no way no I started making my wires without any taper. I started estimating my tubing dimensions based on the real dimensions I was able to find. I try to get close to what that might be for my models, but sometimes I have to just guess.

I've read about software that does make an effort to solve this issue, but I use an old fashion way of trying to determine how close my estimate is...trial and error. Sometimes, if I can find some claims data from a well documented antenna manual, and/or info noted elsewhere as well and I don't need to match the antenna...I can the test the model for match and bandwidth and get close enough for government work.

I also hear as long as you get close in you estimate of the wire size distribution along the length of your wire...it just doesn't make much difference in the real world vs. modeling. This is sorta' like I'm finding, in general, adding the physical match to a model...it just don't matter that much. I think your modeling using the matching features in 4Nec2, also show similar results for the performance indicators, gain, and angle. So when we see a model that does not include the physical match or the mathematical equivalent match in a model...the difference is still minimal.

4Nec2 handles taper different to how you enter it in. It asks for the radius of both sides of the wire, and something it calls L_ratio. It uses this data to enter a single diameter into the Nec2 engine and get an accurate result. However, if you use it for one wire you have to use it on all wires.

I figure now you're are talking about the optimizing feature using 4Nec2. Eznec will not do that directly, but there is software available on the Internet...what claims to use Eznec data descriptions, and build macro's for automatic optimizing the model.

I still can't get my I-10K model, with the trombone added, working to produce the match you're getting. I also am not getting a good Average Gain value for my model in Free Space either. I can find 50 ohms on the T1 end of the tuner, and it shows a perfect match at resonance, but the AG is still off by too much.

I wasn't talking about optimizing specifically, although optimizing does involve variables as well. With the ring on the vector, I was simply talking about how I can manually set and adjust the size of the entire ring with only a variable and some formula's entered into the data part of the model. If I want the ring to be 19 inches in diameter, I enter 19, if I want the ring to be 22 inches in diameter I enter 22. If you have ever used Excel, or another spreadsheet, it is essentially the same concept, although applied a bit differently.


The DB

 

[Marconi]

Linear loading is a loading method generally used with horizontal antennas, but can also work with vertical antennas. Essentially, part of the antenna is folded back onto itself.

I sure hope you keep us posted on your progress on the use of linear loading. If you get something positive for a CB vertical like you talked about...maybe you could email me or post your wires descriptions, and I could go from there.

I agree, the idea you posted above sounds interesting. Hopefully you can get over the issues you reported. I have the ARRL19th edition, and I think it has some of the reference info in your 20th edition. I'm going to take a look at the idea for sure.

Thanks.

 

[Marconi]

With 4Nec2, I say which wire and segment to use. I don't have a % of the segments option. However, if I am using auto segmentation and that happens to change the total segments on said wire, the location of the feed point does not change.

Here is the screen to add a source:



The % is anything from 0 - 100% and then Eznec places the source in a calculated segment, but physically...the red "O" typically shows up at or near the middle of the segment. This function is limiting if you want the source at the junction of the wires...so then you can use the split feature noted in the last field in the source screen captions "type". Just click on the field and a window with 4 choices pops up, V or I, or SV or SI for split. I think all selections are for voltage or current.

4Nec2 handles taper different to how you enter it in. It asks for the radius of both sides of the wire, and something it calls L_ratio. It uses this data to enter a single diameter into the Nec2 engine and get an accurate result. However, if you use it for one wire you have to use it on all wires.

I've read somewhere that the limitation on taper only applies to Nec2 and not on Nec4, and has nothing to do with Eznec, but I could have misunderstood. I'll have to look this up and get back. Taper will does not stop one from adding the feature to your model...but Eznec/Nec2 has difficulty producing accurate results. That said however, it could be taper produces a difference, but as I tend to see in other issues about antennas...the difference is usually very small. I will have to do some more specific comparison models to remind me what I've already tested.

I wasn't talking about optimizing specifically, although optimizing does involve variables as well. With the ring on the vector, I was simply talking about how I can manually set and adjust the size of the entire ring with only a variable and some formula's entered into the data part of the model. If I want the ring to be 19 inches in diameter, I enter 19, if I want the ring to be 22 inches in diameter I enter 22. If you have ever used Excel, or another spreadsheet, it is essentially the same concept, although applied a bit differently.

Rather than use a lot of words trying to describe how Eznec makes a loop, here is an image of the Hoop feature used to make a hoop, and put it anywhere on the model you wish automatically and in a flash. This too is a powerful feature...that in the beginning I had to try and do by hand, one wire at a time. This process was not easy even when trying to make 4 radials attached to the base of a radiator.



With a little fiddling around...this became easy to use right quick. I know some probably marveled at the idea that this old man made all the wire descriptions for the Sigma4, for example, and I took credit for it, but in truth Eznec does it all for you.

This I call slick, and that is why I think Eznec is very user friendly and, within reason, can be very accurate if you understand the limitations.

These are the type of features we can thank Roy Lewallen for designing.

 

[Marconi]

DB, here is page 4 of the 4Nec2 manual that I missed earlier on in this thread. It describes the use of split sources, and describes it function. You can use it too.

Image 0002 PDF. I found it stuck in my printer, it must not have scanned earlier.