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Booty Monster's Vector 40000 thread on Eham
- Thread starter Marconi
- Start date
Hello Marconi,
I understand your giving it your best shot.
But are you sure your taking this direction....
4nec2 using a similair engine is capable of providing a similair colourfull pattern.
What im trying to say...
It depends on the engine the modeling software is using.
Now ansoft is `very active` seeking for buyers...however...its (c) MOM.
There are some differences between a `normal` nec` engine but not
similair to cst etc.
With that said...CST can also do MOM...
Nothing wrong with MOM though...i use it every day.
Infact at a last seminar with CST i discussed it with Frank (one of the guys from CST)
And we both agreed...for normal antenna purpose NEC with MOM is just fine.
(with the limitation provided in the manual)
Perhaps your search could be placed more in other `domains`.
Regards,
h.
I understand your giving it your best shot.
But are you sure your taking this direction....
4nec2 using a similair engine is capable of providing a similair colourfull pattern.
What im trying to say...
It depends on the engine the modeling software is using.
Now ansoft is `very active` seeking for buyers...however...its (c) MOM.
There are some differences between a `normal` nec` engine but not
similair to cst etc.
With that said...CST can also do MOM...
Nothing wrong with MOM though...i use it every day.
Infact at a last seminar with CST i discussed it with Frank (one of the guys from CST)
And we both agreed...for normal antenna purpose NEC with MOM is just fine.
(with the limitation provided in the manual)
Perhaps your search could be placed more in other `domains`.
Regards,
h.
Thanks Henry, but I won't be dropping Eznec too soon, I have too much to try and understand before doing that. Eznec is also far more intuitive.
I heard about this product the other day while checking out BM's thread on eHam or QRZ, and thought I would try it out with a simple 3/4 wave model.
It seems to me the guys here might be more impressed with the colored images, and I was interested to see how another modeling product might handled the current and phase.
I copied the data entry directly from my Eznec model. As best I can tell so far, this model is very similar to what I see with the Eznec model, but I wanted to wait a bit before giving an opinion.
I'm still having issues with the way Eznec handles currents and phase with some of my models. I can't always be sure, but sometimes I see the model with current phase turned on indicating one thing, and the tabular current log showing another. I think I have attempted to discuss this with you, Shockwave, Roy, and a few others before...to no avail.
So, I went looking else where, but IMO this pretty picture thing...probably ain't it. I also though it might help me to better understand what I was looking at in the few images we have from CST.
Thanks.
Henry, to follow up on your remarks I noted in red above.
Shockwave, tells us he found Eznec failing to handle currents in his Dominator model. He does give some details, but I'm not clear as to what he is really seeing.
At times I also see anomalies with some of my Eznec models, and this leaves me to wonder. Henry, I've tried to talk to you about this before.
Example: I'll try to describe this issue in the images below.
View attachment Showing phase problem.pdf
In words, this describes a 5/8 wave model where the Antenna View of the red current indicator with currents turned on, shows a phase change in the radiator just as we would expect. However, when we check the tabular Currents Log in the Currents View...there is no indication of this current shift.
I don't know if this is similar to what Shockwave experienced, but this looks to be a problem, and I cannot explain it. I have talked to SW about this too.
I have other models with phase shifts indicated where Eznec shows the correct tabular currents, and I don't know why this happens either.
See example of Eznec doing the current phase right. Check here: http://www.worldwidedx.com/cb-antennas/151071-skeleton-sleeve-fed-monopole.html
Last edited:
Marconi, I know you're looking for the answer to this question and I can't see how any model could be accurate if the phase angle is not. We would obviously expect to see phase inversion occurring in the bottom few segments of that 5/8 wave and it is not showing this. To add to the confusion, the Skeleton monopole does show the inversion. The best person to answer this question would be Roy but as you know getting answers from him is not the easiest thing to do unless it's "the program can't miscalculate currents". The two models you presented here make it very clear the currents are miscalculated in at least one model. If the program can't make a mistake, I'd expect the writer to be able to tell us how we made the mistake building the model. That too seems absent.
Thanks Donald.
I tend to agree with you on the idea that phase needs to be accurately displayed and noted in the models. It doesn't make any sense to me, but in this case I don't know why we see the current phase difference between these two models, unless it's somehow related to the difference between an 1/8 wave and a 1/4 wave at the base.
Eddy,
Could you be so kind and send me the 5/8 wave model where the current magnitude goes from left to rigth either poelm372(at) planet.nl or info(at) hpsd.nl will do.
Ill look into it...
If i cant find it (im not the guru hihi), ill find someone who can.
Just give me a couple days...time is always limited
Kind regards,
H.
Could you be so kind and send me the 5/8 wave model where the current magnitude goes from left to rigth either poelm372(at) planet.nl or info(at) hpsd.nl will do.
Ill look into it...
If i cant find it (im not the guru hihi), ill find someone who can.
Just give me a couple days...time is always limited
Kind regards,
H.
Eddy,
Could you be so kind and send me the 5/8 wave model where the current magnitude goes from left to rigth either poelm372(at) planet.nl or info(at) hpsd.nl will do.
Ill look into it...
If i cant find it (im not the guru hihi), ill find someone who can.
Just give me a couple days...time is always limited
Kind regards,
H.
I'll send it right along Henry.
Donald, also note in the 5/8 wave model; the point on the radiator where the phase cross-over occurs...does not look to be located at the correct segment point for the model. I have seen this before.
I also recall you asking me a similar question about this issue too...when you recently pointed out the same thing on my Vector model. You suggested I adjust the radiator or the radial length to move that point. That made sense, and I think I did that with the model, but I don't think it changed (fixed it) like you suggested.
I hope I'm clear here, and this makes sense.
Marconi,
You know I am the worst of folks to comment on a model being the modeling novice I am, but when I looked at this one of the
Skeleton Sleeved Dipole I saw exactly the same as with your 5/8 wave model above.
When I counted up the vertical of both of the Skeleton Sleeved Monopole models I found the one not showing inversion agreement between the red current indicator lines and the tabular current data was the one showing a red line crossover of the vertical in segment 8 of the central radiator, and the one where the tabular current data showed inversion was occurring at segment 10, which was the model with the red indicator line not crossing over the central radiator. In other words, the models showed inversion in the tabular current data when the red indicator line stayed on the same side of the central vertical radiator with a simple bump in toward the central vertical radiator.*
Once again, whether I am following all this correctly may be suspect, but I was trying to figure a little of this out as a learning experience.
* red line crossed over = no tabular current data inversion indicated
red line stayed on same side = tabular current data inversion indicated???
You know I am the worst of folks to comment on a model being the modeling novice I am, but when I looked at this one of the
Skeleton Sleeved Dipole I saw exactly the same as with your 5/8 wave model above.
When I counted up the vertical of both of the Skeleton Sleeved Monopole models I found the one not showing inversion agreement between the red current indicator lines and the tabular current data was the one showing a red line crossover of the vertical in segment 8 of the central radiator, and the one where the tabular current data showed inversion was occurring at segment 10, which was the model with the red indicator line not crossing over the central radiator. In other words, the models showed inversion in the tabular current data when the red indicator line stayed on the same side of the central vertical radiator with a simple bump in toward the central vertical radiator.*
Once again, whether I am following all this correctly may be suspect, but I was trying to figure a little of this out as a learning experience.
* red line crossed over = no tabular current data inversion indicated
red line stayed on same side = tabular current data inversion indicated???
You're correct Homer, both the 5/8 wave and the Skeleton models do indicate a phase shift on the lower end of their radiator. This happens in the Antenna View when the model has the phase feature turned on, just as we might expect we see...the familar current cross over.
I hope I'm understanding you correctly here, but there were not two Skeleton models. I did post two images of the Skeleton model however...one with Currents turned ON, and one with Currents turned OFF. I didn't do the same with the I-10K model however.
The point I was trying to make to Shockwave was that Eznec showed the I-10K, 5/8 wave model's tabular data report incorrectly for some reason by indicating there was no cross over noted in the data. However, the Antenna view showed the phase shift correctly for this 5/8 wave model as noted above.
You are also correct and a very good observation on the Skeleton model, when you note that the Antenna view shows the cross-over at segment #8, and the tabular currents data shows it at segment #10. I don't recall for sure if I added a comment to SW about that above, but what you noticed here is also unusual to me. I figure Eznec should probably nail such conditions in its results, but maybe I'm a bit too optimistic.
With Eznec, I can only suspect there is a problem I don't understand in this regard, and I can only hope it is a modeling error I made and we're not just be left with a limitation problem.
On the other hand and without intending to be critical of CST's program, I don't fully understand what I'm looking at in the image we've seen either, but to me the current at the bottom of the Vector looks much smaller than I might have been lead to believe.
The 3/4 model using An-SOF I posted the other day does look to me to suggest the same thing we see in the CST model, that there is some RF at the base of the Vector, but again I note the magnitude of the current and RF is likely very small, and what difference it makes to performance has yet to be determined.
I think it's important to point out that the individual currents on the cone could be 4 times smaller than the one current on the vertical and still have the same magnitude. If you give a single current multiple paths, each path takes an equal portion of the current but the total current is several times that contained on any one radial. The gain this offers locally is almost unnoticeable. On the other hand, in the distance this is often the difference between full copy and no copy.
Well Shockwave, I agree with the principal you site.
But I contend the total current of the 4 radials, when summed, likely exceeds the total out of phase currents from the radiator by a fractional amount less than .005 amps. Thus I contend that the inphase difference left over could be spilling over in the cone area, and radiating constructively with the top 1/2 wavelength.
I also believe it is not likely we'll ever see two elements that totally cancel out...due to their being out of phase. I figure this is what is happening in the cone area of the Vector, and therefore there is some radiation, but the amount is yet to be determined...like I suggested above.
Thus, the majority amount of currents in the cone area are canceled.
BTW, have you heard anything from Dale about the testing he was to do this past weekend?
But I contend the total current of the 4 radials, when summed, likely exceeds the total out of phase currents from the radiator by a fractional amount less than .005 amps. Thus I contend that the inphase difference left over could be spilling over in the cone area, and radiating constructively with the top 1/2 wavelength.
I also believe it is not likely we'll ever see two elements that totally cancel out...due to their being out of phase. I figure this is what is happening in the cone area of the Vector, and therefore there is some radiation, but the amount is yet to be determined...like I suggested above.
Thus, the majority amount of currents in the cone area are canceled.
BTW, have you heard anything from Dale about the testing he was to do this past weekend?
Except the gain has been determined in CST and published by Sirio at 2dbd. Every field test I've been able to participate in confirms this gain and even more when I change out a side mounted dipole to this design top mounted with no tower interfering with the pattern. The evidence is there for those willing to see. One can assume Sirio is not being truthful but this is not Solarcon claiming 9.9 dbi on an Imax. Claims like that don't stand in the field. What Sirio claims is repeatable in the field.
PS: Dale has not posted any more info.