I-10K/Sockwave model first run

[The DB]

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.

I have a geometry editor that I use for some things, although being a math person, I generally do the math myself unless what I need is big, or complex. Four radials offset 45 degrees from the X axis and Y axis isn't hard for me, I just use the Pythagorean Theorem. I've used far more complex equations than that in previous models.. I can enter formulas into 4Nec2 that will make a shape and the size of an object. I don't have to go into a geometry editor and make the item again at a new size, I just change a variable. I have made coil based loads with said tool, it was very useful there. When I made the model of my SUV, I made the grids in the model with said editor, and positioned them so that when I put the grids in a single file they would line up properly. It is a powerful tool, and I can use it well, I just prefer not to when I don't have to.

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.

I've used it in two scenarios, a five foot antenna as a loading for a 1/4 wavelength antenna in various configurations, and in a 5/8 wavelength antenna to tune it to be a 3/4 wavelength antenna electrically.

For the five foot length antenna, linear loading was more efficient than any use of a coil or cap hat, although not so much that you would notice over the other loading methods. That being said, I also wasn't trying to use it to resonate a 40 meters signal on it either. Its biggest downfall is the fact that is skews the pattern of a vertical antenna, one side has more gain than the other.

When it comes to the 5/8 wavelength antenna, the model with the horizontal linear loading system skewed the pattern the least, and it was pretty close to a co called "perfect" SWR match with no modification, well within use able range, the only issue is like the five foot antenna model there is still skewing in the radiation pattern. I modified that model for my first build of the I-10K/Shockwave antenna because it looked so similar, and that model was a success for me as well.

Linear loading is a neat trick, and in some specific cases is as good as it gets, but for vertical antennas it just isn't generally practical, most of my successful model designs would be a pain in the backside to implement physically, especially in a mobile environment for the smaller antennas. This combined with the fact that compared to other loading methods, most people just don't seem to understand how linear loading works.

If I put up a horizontal antenna in the limited space that is my back yard, it will be linear loaded, fed with ladder line, and run directly to an antenna tuner. The goal would be to make the antenna use able, and perhaps as effective as possible, on as many HF bands as possible. I just don't see it being widely used elsewhere, except perhaps some yagi designs.


The DB

 

[Marconi]

Its biggest downfall is the fact that is skews the pattern of a vertical antenna, one side has more gain than the other.

Is the skewing more or less what we might see on a J-Pole?

When it comes to the 5/8 wavelength antenna, the model with the horizontal linear loading system skewed the pattern the least, and it was pretty close to a co called "perfect" SWR match with no modification, well within use able range, the only issue is like the five foot antenna model there is still skewing in the radiation pattern. I modified that model for my first build of the I-10K/Shockwave antenna because it looked so similar, and that model was a success for me as well.

Could I ask you to post the wires description for this 5/8 wave, and I will try and duplicate the model to get started with the linear loading idea. Please let me know the frequency, the wire where the source is inserted, let me know if you use metrics or inches.

Thanks

 

[222DBFL]

This is a great thread and I hope it continues to move forward in the direction it's going. So much good info to be had if people will just read it a few times!! I truly mean that. Keep up the great work gents!!

 

[The DB]

Is the skewing more or less what we might see on a J-Pole?

Its about the same.

Could I ask you to post the wires description for this 5/8 wave, and I will try and duplicate the model to get started with the linear loading idea. Please let me know the frequency, the wire where the source is inserted, let me know if you use metrics or inches.

The wire descriptions...

As you can see, heavy variable use... Here are the variables...

And as the variables page shows, the data is in meters.

The feed point is on wire 5 (or when you look under Tag there is a number 1).


The DB

 

[Marconi]

I have a geometry editor that I use for some things, although being a math person, I generally do the math myself unless what I need is big, or complex. Four radials offset 45 degrees from the X axis and Y axis isn't hard for me, I just use the Pythagorean Theorem. I've used far more complex equations than that in previous models.. I can enter formulas into 4Nec2 that will make a shape and the size of an object. I don't have to go into a geometry editor and make the item again at a new size, I just change a variable. I have made coil based loads with said tool, it was very useful there.

DB, I'm impressed with your geometry skills, but I need the wires descriptions similar to the format posted below. The geometry editor really looks impressive for ease of making changes for sure and Eznec does not have such a feature...at least the version I have doesn't.

I don't know what editor you were using back then when you posted wires for some other project, but this format would be helpful for me.

 

[The DB]

but I need the wires descriptions similar to the format posted below

That doesn't exist in this model, to get what you want I would have to manually enter everything in. That is not how these models work and why I also added the variable list.

Any place you see an "ah" replace it with 11.
"s" is 0.2
"ll" is 0.5711 and
"r3" is 1.94454

If there is a plus sign you add the numbers together. If there is a minus sign before a variable, make it negative.

Watch it as some of those variables have a negative sign in front of them that is easy to miss.

That should be everything you need to get all the numbers you are asking for.

Also, take note, I am using auto segmentation, which is why I can get away with having one segment on many of those wires. As auto segmentation is on, those numbers get replaced before the software calculated anything.


The DB

 

[Marconi]

That doesn't exist in this model, to get what you want I would have to manually enter everything in. That is not how these models work and why I also added the variable list.

Well that is a revolting development (quote from Jackie Gleason days). I understand, but I just didn't want to try and figure it all out and then do all the math...and ultimately end up with errors, and the model fail. I know that 4Nec2 has several editors, but I though maybe they were just different data views and you had a choice which view to print or publish on the Internet.

Don't bother to do it manually, I might get to feeling better someday and take up the task myself.

Thanks for the tips on the math, I think I remember dealing with this before to a lesser degree on one of you previous 4Nec2 models you posted for us.

Also, take note, I am using auto segmentation, which is why I can get away with having one segment on many of those wires. As auto segmentation is on, those numbers get replaced before the software calculated anything.

I have not used auto segmentation. I set my segments to manual, and typically make my models to maximize the segment to show within my limit of 500 segments per model. Typically this works out to be around <>3.5 segments per inch, or <>0.25 segments per foot.

I can set the models to auto and select conservative or minimum. Conservative saves segment over my manual idea, with a little reduction in gain. Minimum does not do well at all, and reduces gain that is excessive. The match on these three segment features is as follows for the antenna I just compared.

My segment idea for my NV4K with my idea for a physical gamma match included: bummer! The numbers below are way too different to suit me...just in changing the segment count for each wire.

VV4K model with matcher. The model show a very good pattern, but it fails on these changes to the segment handling.
SWR = 1.00
Conservative
SWR = 2.08
Minimum
SWR = 3.40

This suggest to me that something is problematic with my model...and I did not know it. I also saw substantial skewing of this antenna pattern. It looked great with my segment setting scheme, but the pattern was skewed when I switched from manual segments to automatic segments, and selecting both Eznec's idea for Conservative or Minimum.

I ran this same comparison using a CFHW model that produces the gain and match that science tells us, within reason, is correct. R=72.56, X= -0.02, SWR = 1.45. This model did not skew the pattern, and only made a minimum of change to the gain.

So, I will have to look into this further...it may be a sign of errors in my modeling or it could be reflecting the importance of getting the segment right, and/or the problem with doing nothing vs. using too few segments.

My manual speaks of segmentation and says it is a variable and each operator has to determine what works for himself. It also says this is what usually happens with different folks...that get an idea and use it routinely in their model making. It also warns of pitfalls in the process of assigning segments to any model.

DB, could you check this out with some of your models and see if you get different results from mine.

 

[The DB]

Skewing shouldn't be substantial, that is odd. When I use auto segmentation, I give it an amount per half wavelength, and the modeling software takes care of it for me. Sometimes I change this some in the process of modeling... I have, in the past, compared a manual and auto segmented comparison models, I got identical results. That being said, I made sure all the elements had the same number of segments between the auto segmentation and the manual counts, so they should have been exactly the same. I haven't seen anything where auto segmentation causes significant skewing where the model without auto segmentation has little to none.

If you still have the .EZ files, you can send them to me, I can load them directly into 4Nec2 and see if I notice anything.


The DB

 

[Marconi]

That doesn't exist in this model, to get what you want I would have to manually enter everything in. That is not how these models work and why I also added the variable list.

Any place you see an "ah" replace it with 11.
"s" is 0.2
"ll" is 0.5711 and
"r3" is 1.94454

If there is a plus sign you add the numbers together. If there is a minus sign before a variable, make it negative.

Watch it as some of those variables have a negative sign in front of them that is easy to miss.

I understand about a model not being available in all the editors DB. I watched the sign (-) real close and I think I have the model's input into my wires description window done correctly, but the model still fails.

I get errors that I think are similar to what you noted with my model the other day. As noted below I get 3 segment minor errors and a critical error. Also note that the longest wire in the model, for the radiator wire #11, has only 1 segment in your model. Is this right that the radials have 25 segments for 9', and the longer radiator only has 1 segment for over 20' feet?

Also, take note, I am using auto segmentation, which is why I can get away with having one segment on many of those wires. As auto segmentation is on, those numbers get replaced before the software calculated anything.

I regret a little bring up the subject of Auto Segmentation in this thread. It is a good subject DB, that maybe you and I could hash out, as to differences in the software in another thread. But new', the cat is out of the bag now, so here I go discussing segments anyway.

If there is a plus sign you add the numbers together. If there is a minus sign before a variable, make it negative.

I watched this carefully, but here is my wires descriptions...maybe you can see some error that I am missing.

Watch it as some of those variables have a negative sign in front of them that is easy to miss.

I tried to be careful and I agree this is difficult data entry.

That should be everything you need to get all the numbers you are asking for.

Thanks for the model, but I'm not sure what frequency you used with your model. So, I entered you numbers and had Eznec set at 27.205 mhz. Is this a problem?

Also, take note, I am using auto segmentation, which is why I can get away with having one segment on many of those wires. As auto segmentation is on, those numbers get replaced before the software calculated anything.

I'm not sure about how 4Nec2 works on your end using Auto Segments, but when I set Eznec up to do a model and I want to use Wavelength as a rule for dimensions...I activate this using the Units feature. This sets the units of measure for the dimensions to a % of wavelength I believe. It also does the dimensions in wavelength, but in Eznec this is a function for dimensions...not for segments.

Skewing shouldn't be substantial, that is odd.

Here is a pattern of my I-10K w match 36' with my idea for segmentation.


Here is the same I-10K antenna pattern as noted above, but I changed the segmentation to conservative.


This is the skewing I was talking about that resulted in the model after I changed the segments form my scheme to Eznec's idea of conservative.

When I use auto segmentation, I give it an amount per half wavelength, and the modeling software takes care of it for me.

Are we talking apples and oranges again?

Sometimes I change this some in the process of modeling... I have, in the past, compared a manual and auto segmented comparison models, I got identical results.

Are you possibly talking about Units here and not Segments?

That being said, I made sure all the elements had the same number of segments between the auto segmentation and the manual counts, so they should have been exactly the same.

This is what I would expect also. I also tested a CFHW dipole that had a good pattern and match where the results indicated what science says we should see with a model. There was no skewing when I changed the segments from my scheme to conservative or minimum.

I haven't seen anything where auto segmentation causes significant skewing where the model without auto segmentation has little to none.

If you still have the .EZ files, you can send them to me, I can load them directly into 4Nec2 and see if I notice anything.

How do you want this file...in an exe of the whole model, or just an image of the wires description?

 

[Marconi]

DB, could you post the results from the linear loading model you posted above. My model is no-way-no and it doesn't seem to respond differently no mater what I do with the segments. The match is also terrible and the gain is in the (-) negative.








We can see that the current on the radiator has no power, and that is not good.

Below is the antenna with currents turned on and it shows even less current on the radiator.

 

[Marconi]

DB, BTW I cannot get the value of r3 to = 1.94454

rl= 2.75
I get r1 = 2.752 = 7.5625
I get r2 = 7.5625 / 2 = 3.78125
I get r3 = 3.781252 = 14.297851 x .5 = 7.1489255

Where did I go wrong here.

 

[The DB]

DB, BTW I cannot get the value of r3 to = 1.94454

rl= 2.75
I get r1 = 2.752 = 7.5625
I get r2 = 7.5625 / 2 = 3.78125
I get r3 = 3.781252 = 14.297851 x .5 = 7.1489255

Where did I go wrong here.

I'll respond to the posts above this one tonight or tomorrow, but this I can do quickly.

You went wrong at r3. What I did was take what was in r2 and raise it to the 0.5 power, that is another way of calculating a square root. You squared that result and then multiplied it by 0.5, which is not the same thing.


The DB

 

[Marconi]

I'll respond to the posts above this one tonight or tomorrow, but this I can do quickly.

You went wrong at r3. What I did was take what was in r2 and raise it to the 0.5 power, that is another way of calculating a square root. You squared that result and then multiplied it by 0.5, which is not the same thing.

The DB

You didn't say anything about my math being wrong for r1 or r2, and I used the caret to mean square the rl = 2.75.

Could you explain how you raised the power of r2 for r3 by .5?

I'm not a math man.

 

[The DB]

You didn't say anything about my math being wrong for r1 or r2, and I used the caret to mean square the rl = 2.75.

Could you explain how you raised the power of r2 for r3 by .5?

I'm not a math man.

I don't know if there is an easy way of explaining that offhand. As far as typing it out, you use the ^ symbol to denote a power, and .5 after it is the power raised to. When it comes to powers, you don't have to have a whole number, such a 2 for squared, or 3 for cubed. What I did was raise r2 to a power of 1/2, or .5, which is the inverse of 2 and therefore calculating the square root.

Take it as simply another way of calculating a square root if you don't have a square root button or symbol available.

I don't have an easy explanation for you beyond this.


The DB

 

[Marconi]

It's easy to suggest taking the square root of a number using a scientific calculator. This will save you a lot of time vs. doing the math by hand.