Marconi's Eznec model for the AS Super Magnum 1/2 wave GP

[Henry HPSD]

Dont think I have said that....
At least it wasnt my intention.

But now i think i understand what you guys are after ....
You want to explore the AGT behaviour between "freespace" and "perfect earth"
?

Speaking from my mind....above "perfect earth" the figure should be 2 in 4nec2
Does that sound familiar ?

Kind regards,

H.

Edit:
PS..what is it that you guys are after ? what is the bennefit of exploring the AGT above a "perfect earth" in relation to "free space" ?
It makes me wonder....as i dont know....and most certainly willing to learn Tnx !

 

[Marconi]

Henry, I don't know for sure, but I always had the idea that the use of Perfect Earth was used in some process for determining losses somehow.

To me the pattern that PE generates is more similar to Real Earth, and maybe this is why I misunderstood DB's words.

I think I got my ideas about PE in reading the manual, but I have never had enough curiosity to even study what Perfect Earth is really used for in modeling.

When I have at times selected Perfect Earth I think I probably saw the AGT value increase in value over the FS value...which is the wrong way to go IMO.

I use only Free Space when I run my AGT.

 

[Henry HPSD]

Hi Marconi !

The AGT function is an important tool to find out if the model is "correct"
With that said... it still is possible to have a bad model with a good AGT, but ...
If the AGT gives a bad indication... you know up front there is something wrong.

It is important to roughly understand the "concept" of it.

The "software" says: (rough example)
Im providing the antenna with 100 Watts..
THats a certain amount of "energy".
The software compares that "energy" which makes that big radiation lob.
If there is differences.. for example due to the use of aluminium or coils etc..
Those two wont be "equal" and the figure wont be 1.

So... you know you need to illuminate all losses up front in order to keep the balance between the "power" that goes into the antenna and the power which is radiated.

There are btw more "tests" to verify a model.

I often use "perfect earth" to show the influence of ground effect.
With that said....in a "perfect earth" situation there is NO loss due to ground effects and it can be used to obtain a AGT figure.

That is the "key" for setting up a good DX station btw.. the ground and how it is situated is the most important aspect of a "DX" station and only then antenna height and type of antenna
(although it is open for debate of course ....just giving personal opinion)

 

[The DB]

Speaking from my mind....above "perfect earth" the figure should be 2 in 4nec2
Does that sound familiar ?

I haven't seen anything that specifically states that. 4Nec2 still gets very near 1 on my models when an earth is included. The I-10K/Shockwave model from a different thread for example, AGT is exactly the same weather AGT is run over an earth or in free space.

I guess if they didn't include the calculated values from below the horizon then the result would change, but with most of the models I have made that doesn't seem to be the case, I generally get very similar results between the two possible AGT environments. I guess the question is, do they still count all of the directions from below the horizon which should all now be 0, if the answer is yes then there will be no change, if the answer is no then you should expect to get a 2 instead of a 1, although I suppose they could also take the result over perfect earth and divide it by 2 as well and get the same result to keep it consistent.


The DB

 

[Henry HPSD]

If allowed.. from my perspective:
I think you gave (and know) the answer..

Its either gonna be 2 or 1.
I mentioned 2, cause in the past:
I have used software named..ehm..
Antenna Model, think its called that?
From Teri software based on MININEC .

Anyway...I remember at a time I had the same question.
Memory says, the value AM used was 2.
So I would have thought it could be 2 in 4nec2, but on the other hand it seems easy to add a software line "/2"
With respect: Im hoping we are not going to debate it needs to be either 1 or 2...as whats the use of doing so ? If one understands why it is 2, you understand the concept.


Far more interesting...

Marconi I know you have used AN SOF, and maybe DB has too ?
Perhaps focus should go to explore an-sof a bit more...
(or other software other than traditional MoM)
What i see is that people put up a EZNEC plot, and people say: owh...oke...thats it then.
But we all know the limitations and capabilities of software...it isnt always "oke"..

AN SOF is software which uses cMoM.
Although Im not aware about difference in the equations
(dont think im capable of understanding all either hihi)..

I do know, at this point i tend to think:
I am in favour of it in aspect to NEC in some cases (including NEC4)

The software isnt well known..
Perhaps cause its too cheap ?
The Pro version is only a fraction of what i paid for the commercial NEC4 version, and it is really fun !

I consider my self as one of "those" who is at a stage where he thinks he is an "oke" NEC user.
I dont know all the math...why...but im capable of finding out why, and i havnt been amazed in a long time, i can "explain"...I dont know all...but i know where i need to "search".

All my files are NEC, there isnt a day where I dont use NEC in one way or another.

All basic software like MMANA 4NEC2 EZNEC AM etc.. all provide within the limitation the same result (logical)
But all have more or less the same "borders".

An Soft has suprised me, where NEC had issues.
It provided results beyond NEC which I tend to find accurate due to testing done.

And yes ... obvious one can use other advance software...
Though Important for me (and most?)
an soft has the option to upload NEC files... i couldnt do that with "others".

Cant help it...im getting old too hihi.

Basic ideas are made with the software you "learned" to use..
I always start with Eznec. then I turn to "others" to optimise. ....when done...
I return to EZNEC with that "AutoEZ" and get myself some nice plots.
Not because "others" are not capable, but for most due to "speed" of "things"
Using AN Soft for "development" is a horrible...
But is capable of providing solutions and answers where others cant

 

[Marconi]

______________________________________________________________________________

Henry I posted the text above in my post #4, and it was in response to DB's claim that 4Nec2 can produce an AGT report on a model over real earth, because the 4Nec2 software changes the model's "Ground Type" to "Perfect."

Apparently the difference in this long and complicated discussion about Average Gain is due to the difference in procedures and that is about all that needed to be said. I would however love to have a discussion about AGT in another thread. IMP it is an important topic in modeling.

I'll get into trouble again for saying this, but this this stuff about AG in this case is not very productive and is a waste of words. We are all talking and saying about the same thing...just using different words looking at the issue from different viewpoints.

I anticipated this, and is the reason I said I would post what the Eznec manual says on the subject, but I would not get into a discussion of the meaning of AGT.

Problem is I was having a terrible attack of drug reactions at the end of my post here, and I did not want to argue the point. I also forgot to post the part in the Eznec manual on the subject. Sorry for that.

So, here below is the PDF file for all to read and make up their own minds about what it means.

I often get accused of not understanding stuff, and then there follows a thousand words that solves nothing after it is said and done. I hear the echo of politicians in governments all over this world and it saddens me.

So, you two carry on while I try and get over this drug-reaction, and maybe while your both at it...tell us what "2" means. It must have some secret meaning between you and DB.

hehe!

 

[The DB]

So, you two carry on while I try and get over this drug-reaction, and maybe while your both at it...tell us what "2" means. It must have some secret meaning between you and DB.

It is a math thing, let me see if I can explain where the discussion on AGT possibly being a 2 over a Perfect Ground comes from.

In free space we are taking gain measurements in a sphere. All three axes go on forever in both of their directions. Think of it like a ball where the outside of the ball is infinity.

Now, cut that ball in half and remove one of those halves completely, this is AGT over a perfect ground, same amount of total power, half the space. In this "half space" you get twice the power density because said power will reflect off of the "perfect ground" and return to that part of space instead of continuing in the direction it was going. Because of this, the power density spread through this "half space" is doubled when working with the same amount of power in "free space", which by definition doesn't have said ground plane of any kind.

If you kind of get this concept, stop here, the rest may confuse you again.

We know in free space that all gain in all directions will average to 1, essentially you are comparing to a theoretical dBi antenna. Any additional power in one direction much come at the expense of power traveling in another direction. There is no exception to this rule. This is why AGT in free space should come out to be 1, in reality it is averaging out to 1 dBi.

Now, think of the "half space" mentioned above, and where that half space ends the power is not lost, instead it is reflected back into said "half space", we will call this reflective edge of space a "ground", and more specifically a "perfect ground".

As stated above, the same amount of power within that half space will be measured as twice as high. That is where Henry got the AGT of 2 over a ground from. However, this is only the case if the measurement directions from "below" said perfect ground are not factored in. These measurements will all be 0, however there will be just as many measurement directions from below the "perfect ground" as there are "above". The AGT of 2 idea requires that all of these points "below" the "perfect ground" are ignored when calculating AGT over said ground. Based on prior experience, I'm reasonably sure this isn't the case, and even if it were it could be corrected to an AGT of 1 in the software by simply dividing the AGT result over "perfect ground" by 2 when AGT is run over a ground.

I know that is rather analytical, that is why I said above if you kind of get it stop there.

Long story short it comes down to two questions. When a ground is factored in to AGT, do half of the possible gain measuring directions that are averaged disappear or not? And if so does the software take other steps to account for said difference or not?


The DB

 

[Marconi]

I think I understand your idea as you described, but like I think I told Henry...I'm not real sure what the purpose for Perfect Earth is in modeling.

I played around with a FS model of a CF 1/2 wave dipole that showed virtually the same results as science predicts for the design. In the PDF file below I reset it using Perfect Earth, and the pattern does appear to look similar to a real Earth pattern. So in that regard the AGT does appear to be working over Real Earth as you noted.

However, I did see the gain increased, but it was a lot more gain than doubling what FS shows at 2.14 dbi @ 0* degrees, PE was close to 3.35 times as much gain at 7.14 dbi.

So, I'm still not sure what the "2" means.

I did not see the power double either, it was more than double for PE vs. FS, unless you want to measure the gain at 0* degrees (Earth's horizon) like the FS model shows. Then there is not even a fair comparison, the FS model shows 2.14 dbi at 0* degrees vs. the PE model showing (minus) -99.99 dbi at 0* degrees.

The AGT and the match did not change.

 

[The DB]

Eddie, you are overthinking this.

I played around with a FS model of a CF 1/2 wave dipole that showed virtually the same results as science predicts for the design. In the PDF file below I reset it using Perfect Earth, and the pattern does appear to look similar to a real Earth pattern. So in that regard the AGT does appear to be working over Real Earth as you noted.

In 4Nec2 anyway, when running AGT, "Real Earth" is converted to "Perfect Ground". While they are both grounds, they are not the same. Like "Free Space", one is a theoretical construct, the other is a simulation of the soil that exists in the world. The soil that exists in the world as well as "Real Earth" is lossy, if losses are present AGT does not work. Period. End of story.

Another way of saying this is AGT can only be accurate in a lossless environment, and the only lossless environments we have access to in modeling are "Perfect Ground" and "Free Space", neither of which exist in the real world. So to say AGT works over "Real Earth" is a misunderstanding at best, no matter how similar "Perfect Ground" results appear to be close to "Real Earth", they are not the same.

However, I did see the gain increased, but it was a lot more gain than doubling what FS shows at 2.14 dbi @ 0* degrees, PE was close to 3.35 times as much gain at 7.14 dbi.

So, I'm still not sure what the "2" means.

I did not see the power double either, it was more than double for PE vs. FS, unless you want to measure the gain at 0* degrees (Earth's horizon) like the FS model shows. Then there is not even a fair comparison, the FS model shows 2.14 dbi at 0* degrees vs. the PE model showing (minus) -99.99 dbi at 0* degrees.

You don't need to worry about that 2, as I have shown and discussed, Nec2 accounts for the change in question so that 2 never happens.

We were also talking about AGT in said environments, not the maximum gain point produced, so in this case you are looking in the wrong place all together.

The power doubling is also not being tested in the context that we were discussing. The total power being transmitted does not double, and in fact stays the same. What we are saying is the average power in a half region of space is twice as high, and this is because we are in a half region of space instead of a free space. However, Nec2 is smart enough to account for this, so this is something that you won't see Nec2 show.

The AGT and the match did not change.

This, right here, at least referring to AGT, not the match, is all we were talking about. All of it. You have demonstrated again what I stated above, good job.

Let me state this one more time, the AGT of 2 we were talking about as a possible result will never happen in the software er use because the Nec2 engine is smart enough to account for this change and report AGT as 1 instead.

Like I said above, you are seriously overthinking what Henry and I were talking about, and at least for part of it went way off in the wrong direction. Apples and oranges again...


The DB

 

[Marconi]

Actually, I can run AGT over earth. Nec2 sets the ground to "Perfect" for the AGT test.

DB, I think the comments you made above are what had me thinking that you were able to get an AGT results with a real Earth model...irrespective of your comment the model was automatically set to "Perfect."

I think you are now saying, you cannot get an AGT results using a real Earth model, but that is what I recall and what confused me. Henry can speak for himself, but I think he was stimulated to say something too.

I can do the same thing you suggest here, but I have to run the model in 3D mode or it will not produce an AGT result.

When you read Eznec instructions for AGT you will note the idea is perfectly clear. It does say a few words about real Earth models, but it talks about evaluating the amount of loss of wire resistance in the field with a finitely-conducting real ground (GP/Earth). I believe 4Nec2 does have a different process for making AGT work, but the results are probably not different.

Just curious if you generally use a mast in your real Earth models?

Do you then remove the mast...when you set the model up in Free Space before you run your AGT?

I made the free space version of the model in 4Nec2 and noticed the same thing. If I put the feed point at the base of the radiator where I would expect it to be, AGT goes above 1.2, which is saying the model is not even close to accurate. I don't like putting the feed point at that location, but I guess that is a limit of the modeling software based on that design.

If you read the Eznec manual I posted, you will see there is a compromise solution for the error 1.2 as you noted in the AGT results. I'm not sure what 4Nec2 shows, but its results should be similar and maybe it too makes a fix for the gain portion of the report as well.

I won't try and interpret the meaning, but I don't see how the AGT over real Earth can produce viable information

DB, I said early on in my remarks I would not try and interpret the meaning of AGT, because I had a sneaking feeling an AGT discussion would likely be a hot bed of problems, and I did not feel good.

AGT isn't calculated over "real earth", if you are modeling over an earth, Nec2 uses "Perfect Ground" instead..

What you suggest here, I also suggested at some point to Henry. I said this issue was only about the difference in process between Eznec and 4Nec2, and I argued all the words that ensued...were not necessary.

When modeling over an earth, the AGT result, while not always exactly the same result as running AGT in free space, is still very close.

I agree and I said the same.

I'm confident you know enough about the AGT results to use the feature. I think I'm close as well, but apparently Henry has a different idea that we should also understand that the answer could be 2 in some modeling software. At this point I don't agree with the 2 idea that you gave me a long explanation for how the idea works.

So I'm not sure about you and Henry, but I don't think I was over-thinking this subject. I did try to demonstrate what I saw regarding the use of PE vs. FS as it regards the AGT. So, I used a CFHW dipole model that shows results that are similar to what science suggests the typical match, gain, and angle should be. I did this as a base line for comparison between a Perfect Earth and Free Space AG.

Eddie, you are overthinking this.

Yes DB, you said that already, but this "2" business is not my idea. Now you have me wondering...if this is really Henry's idea or yours? I wish I did understand what the "2" was describing.

After I read more words after Henry made mention about the "2" issue...and I got the idea that maybe he didn't agree either. You then posted an explanation. So, now I wonder whose idea it really is. I'll read your post over again.

Now maybe I'm over thinking.

 

[Henry HPSD]

Hi Marconi....

You are thinking to complicated hihi.
Read post #22 from DB.

Sorry for all the confusion i might have brought up ?
...I was just wondering why anyone would model AG over real earth ?
I mean...if you "effect" the average gain figure ...that means there is loss.
A "perfect" model will show 1 (or 2) depending on software u use.
Now...if this "loss" is due to ground or material or whatever...there is loss...
So beyond the "theoretical" question ....
I cant seem to find the point of exploring the AG in a real life situation.

In regards to post 22...i just made a very quick sketch of what is said.... possible it could help why we (I) mentioned 2 ..

Kind regards,
H

 

[Marconi]

You are thinking to complicated hihi.
Read post #22 from DB.

Thanks Henry. I promised DB I would read it again, but in the process...I didn't express any quarrel...as noted here:

I think I understand your idea as you described, but like I think I told Henry...I'm not real sure what the purpose for Perfect Earth is in modeling.

Henry, maybe you didn't read my comments after the discussion focused on the AG theory and your comments about a mysterious "2" regarding the AGT. I think you did comment by asking DB if he recalled a previous discussion about the mysterious "2" hehe!

I was just trying to explain to DB a little of what I thought I understood about his post #22. None the less I wrote what I thought and you two started accusing me of not understanding. Well OK, I guess that is fair.

The following is not my nature, personally belittling others and I don't read minds with much success.

How is that? hehe! Your personal words didn't make me feel informed or good, how about you?

Sorry for all the confusion i might have brought up ?

I don't think you need to apologize Henry, you just gave us a brief idea on what you thought and/or what you and DB had discussed earlier about AGT. I simply asked questions and maybe you took exception in my asking. That is the way I took your accusations that I was overthinking the subject.

...I was just wondering why anyone would model AG over real earth ?

How about you ask DB that question...I was curious about what I think I read regarding his remarks on the subject too, but I originally directed my question to you.

I never brought up or talked about doing my AGT over real Earth...I knew better. So, I figured DB had misspoken or he would somehow explain. I tried asking him question and made some comments. Then it seems to me your idea likely was; "....lets change the subject over to old Marconi...he is off the tracks again as usual," or something to that effect.

I mean...if you "effect" the average gain figure ...that means there is loss.
A "perfect" model will show 1 (or 2) depending on software u use.

Then Henry why didn't you just explain that and tell us what you meant, maybe even show us the picture you just posted?

Now...if this "loss" is due to ground or material or whatever...there is loss...
So beyond the "theoretical" question ....
I cant seem to find the point of exploring the AG in a real life situation.

Henry I haven't thought about your point here, but since Eznec does not produce an AGT report over a real Earth model...I can't seem to find the point of exploring the AG in a real life situation either.

Who do you think was suggesting this idea, me?

In regards to post 22...i just made a very quick sketch of what is said.... possible it could help why we (I) mentioned 2 ..

It has been said: "...an image is like a 1000 words."

A good drawing and maybe effective at explaining your idea to others that are overthinking what your words mean.

I also had a bad day at the end of this thread. hehe!

 

[The DB]

...I was just wondering why anyone would model AG over real earth ?

How about you ask DB that question...

He did, I never once said I ran AGT over real earth. My first statement about running AGT over an earth in post 2 of this thread was:

Actually, I can run AGT over earth. Nec2 sets the ground to "Perfect" for the AGT test.

When Henry brought it up I showed Henry the code that 4Nec2 generates to show that in fact AGT was run over Perfect Ground, in spite of the setting I had in the model. With the software I use I cannot run AGT over "real" ground. I have stated this multiple times during this thread. I have never even considered that it was possible to run AGT over "Real" ground.

I never brought up or talked about doing my AGT over real Earth...I knew better. So, I figured DB had misspoken or he would somehow explain.

Again, I never said such a thing. The first time anyone mentioned running AGT over real earth was you in post three of this thread...

I won't try and interpret the meaning, but I don't see how the AGT over real Earth can produce viable information...

This is the first time anyone mentioned anything about AGT and "real" earth in this thread, and in my experience, on this forum. Based on what you were responding to I think it was a misunderstanding of the statement I quoted above. Then again in post 5 I stated:

AGT isn't calculated over "real earth", if you are modeling over an earth, Nec2 uses "Perfect Ground" instead.

The second time I stated this in two posts.

Then in post 6 you wrote:

You are right, Eznec can use Perfect ground and Free Space to generate the AGT, but my models show a little difference. I misread you words thinking, when you said 4Nec2 would generated an AGT for a real Earth model if you set the ground to Perfect. You obviously meant something else, and I missed it.

Here we were on the same page on this and all was well in the thread, at least about this part of the discussion.

Then in post 11 Henry came in and posted:

agt can not be calculated over real earth.

This and what he posted immediately after that in his first post in this thread. He likely saw AGT and "real" earth being used together when you misunderstood me before that and read into it even though the misunderstanding between us had already been resolved.

The strange thing is all three of us are, and always have been, in agreement that you cannot run AGT over "real" earth.

but since Eznec does not produce an AGT report over a real Earth model...

That is good to know. Neither of the programs we use will allow this to happen.

Henry, maybe you didn't read my comments after the discussion focused on the AG theory and your comments about a mysterious "2" regarding the AGT. I think you did comment by asking DB if he recalled a previous discussion about the mysterious "2" hehe!

I wouldn't worry about that mysterious "2", at least as long as we are using software that uses the Nec2 engine as its core. While the discussion between Henry and myself was valid, the Nec2 engine compensates for "Perfect" ground AGT in such a way that if it does come up it is modified to be consistent with the free space expectations before it ever makes it to our outputs. It is essentially a conceptual (or hypothetical) exercise that is based on a few assumptions, and can be resolved in any number of ways. It is past us, and at least as long as we use the software we are currently using you don't have to worry about it.


The DB

 

[Marconi]

Very good recap DB.

I think this whole thing, toward the end of this thread, was a misunderstanding from the get go.

It is likely if we were all talking face to face...this matter would have been resolved quickly, with a couple of questions.

I apologize to you both for my part in that misunderstanding.

Thanks for helping clear this up.

 

[Marconi]

DB, I just updated my version of An-Sof like Henry suggested earlier in this thread. It is totally different from what I recall.

I went to YouTube and looked for a tutorial for the V 3.0 and Louis Bergman has one as noted here:

I noticed on my computer monitor that the video was unclear and hard to read, like I remember telling you when I complained about your video looking similar. I'm thinking now that maybe I was wrong and the fault I accused you of having in your nice video was on my end. If so, I apologize.

Maybe you or any other member can check out the link and tell me if all the little text is clear and easily readable. I don't want to waste my time working with this new version of An-Sof and find out the problem is with my stuff.