Marconi's Penetrator 500 Eznec model

[Marconi]

This model for the 500 is just preliminary in design. I don't consider it accurate yet, because of the Average Gain Report. More work to do, but I'm trying. I have included some output for my I-10K for comparison, and both antennas are set on a 40' foot mast.

I've included the real Earth patterns, free space patterns at maximum gain and at zero angle, along with a pattern overlay, antenna views including a close up of the HyGain mount and raised radials, and match report (Source data) for both models.

The HyGain Average Gain shows to be AG=2.681=2.26 db which is not good. If the AG of 2.26 db was subtracted from the reported gain, the models show to be closer together regarding their actual free space gains.

The thing that amazed me was the apparent reduction in matching requirements noted with the HyGain design. However, if I can get the antenna more accurate based on the AG feature, this matching condition is likely to change.

View attachment HyGain Penetrator 500.pdf

 

[Marconi]

For the first time in my modeling of vertical antennas I see a pattern with both vertical and horizontal patterns noted for this Penetrator by Eznec. I don't know the significance as yet, but for me it is remarkable. The horizontal pattern does not show to be strong, but it's there.

If correct it is a weak in signal, but I wonder if this could this be the affects caused by HyGain's raised radials? I use to think and claim that this might be the reason I saw the real world antenna responses I did with my AstroPlane antennas, and could it be why it seemed to work DX so well.

View attachment Penetrator 500.pdf

 

[bob85]

eddie, can we see the current plot, does it show where the horizontal is comming from or is it a lack of cancellation in the radials thats causing it?.

 

[Marconi]

eddie, can we see the current plot, does it show where the horizontal is comming from or is it a lack of cancellation in the radials thats causing it?.

Well Bob, I just noticed the horizontal pattern today. However, I'm not sure I understand what you mean, "...can we see the current plot..."? If you want to see the tabular form of the currents...then I can post that. If not, I posted the patterns with the currents ON (in red). If you want to see a current pattern like Siro's software shows currents, then I can't do that.

I'm still not sure I understand currents, even in the tabular form. Other than the Antenna View showing a descriptor for Horizontal Pol and Vertical Pol, and the light green colored indication of the horizontal pattern in the chart, I have no idea what or where the currents come from. I would guess they come from the radials however, and you may be right...this could be due to lack of cancellation with the radials.

I have posted another view of the mount below, and you will notice the red current line for the radiator does not terminate at one of the radials like the I-10K does. That is a difference, but I don't know what it means. If you can't read the text I added to the image, the top says "Not Here" and the lower comment says, "current terminates here."



This model has a few problems in the mount and raised radials idea I used. The top of the mount is square and the bottom is a triangle, and that probably makes a difference in the results. It is skewed and the model probably is too.

I wasn't looking for a horizontal pattern to show up, so I have to study the model more and try to fix this problem.

When working with wires that do not follow the plane for the x and y coordinates, their dimensions lengths are noted to be different than what we see when the wire follows x or y. I didn't say that very well, but the model is complicated.

Specifically: wires 9,10,11,12 do not follow the plane of x or y as you can easily see, they are tangent instead. The data dimensions for these wires, as shown in the Wires View, shows them to be 2" in length. But, due to the problem noted above, these wires are actually 2.84282" long. I need to fix this, because the HyGain mount is approximately 3" square at the top and bottom flanges where the radiator sits.

 

[bob85]

thanks, thats what i wanted to see eddie, i don't know where the horizontal plot comes from, i was thinking maybe unequal current distribution in the radials but its not obvious in the plot.

 

[Marconi]

thanks, thats what i wanted to see eddie, i don't know where the horizontal plot comes from, i was thinking maybe unequal current distribution in the radials but its not obvious in the plot.

Yep, I wish I understood more. I'll try to fix the model and maybe that will fix some issues with the Average Gain problem. I wonder what HyGain would say about this horizontal polarity thing?

All the patent numbers on the manuals lead to nowhere or a very large group of similar # with a different prefix. Do you have a link to a patent for the 500?

 

[bob85]

i have never found any patent for the hy-gain antennas eddie, im not sure they were patented, if they were nobody in europe took any notice, back in the day there were several antennas available over here with the same style bracket and elevated radials,

i don't understand eznec so i have no idea why its showing a horizontal plot along with the vertical plot, do the tabulated currents show an imballance between radials?
that setup looks to offset the radials but id be a little surprised if that caused what you are seeing in the plot @27mhz,
you could try lengthening the 2 radials on the bracket side of the mounting plate a few inches to see what that shows in nec.

 

[Marconi]

i have never found any patent for the hy-gain antennas eddie, im not sure they were patented, if they were nobody in europe took any notice, back in the day there were several antennas available over here with the same style bracket and elevated radials,

i don't understand eznec so i have no idea why its showing a horizontal plot along with the vertical plot, do the tabulated currents show an imballance between radials? that setup looks to offset the radials but id be a little surprised if that caused what you are seeing in the plot @27mhz, you could try lengthening the 2 radials on the bracket side of the mounting plate a few inches to see what that shows in nec.

I think the old manuals show a patent # on the front page. It is shown as PN 801366, and that is the one I described above. Older manuals show different numbers, but I get similar or no results on searching.

The tabular current reports for a 5/8 wave show a very confused set of currents values per segment. I think my model for the I-10K is about the same mess as this SP500. See here:

View attachment current list.pdf

The mess looks like a wire's end coordinates and not the normal amperage value one might expect. So, I don't understand what that means.

Maybe Henry can help with this. It may be my model errors or it could be something else. My 1/4 wave models look great in this regard and just as you would expect, but typically so does the match in those cases. So I don't know but what a good match vs. a bad match might be the causes of such issues.

 

[bob85]

eddie, i tried the pn numbers from several different hy-gain antenna manuals in the uspto.gov website way back and found nothing,

if im understanding the tables right the i10k current mags follow the taper id expect for a 5/8 vertical ,
you see the verticals current drop as you move from the feedpoint towards a point 1/2wave from the tip, peak 1/4wave from the tip and drop again to the lowest figure at the open end with values less than .001amperes listed exponentially 8.6E-4 = .00086amperes

the radials show equal current magnitude, lowest current at the open end as you would expect,

does the p500 show the same equality in the radials?

 

[Marconi]

eddie, i tried the pn numbers from several different hy-gain antenna manuals in the uspto.gov website way back and found nothing,

if im understanding the tables right the i10k current mags follow the taper id expect for a 5/8 vertical ,
you see the verticals current drop as you move from the feedpoint towards a point 1/2wave from the tip, peak 1/4wave from the tip and drop again to the lowest figure at the open end with values less than .001amperes listed exponentially 8.6E-4 = .00086amperes

the radials show equal current magnitude, lowest current at the open end as you would expect,

does the p500 show the same equality in the radials?

Bob, PN could mean part number to HyGain.

You're right-on the mark regarding the exponential numbers, but out of convenience I didn't use tapper in either model...so something else is controlling the changes in segment values. Thanks for the tip. Another good day for learning.

This issue may be the reason why using tapper can be a problem, unless somehow you're able to control equal segment lengths among ajacent wires.

BTW I think I did try to make all segment lengths for the radiator and radials equal 1' foot. You can see the number of segments per wire in the tabular list of currents attached below.

View attachment Currents I-10K vs. SP500.pdf

Bob, forget the other current list for my I-10K. I just pulled it out at random to show the current numbers. The file above for the 1-10K has been adjusted to equal the SP500 model we are discussing.

 

[bob85]

i don't understand the phase table because i never looked into nec any further than a cursory peak, i remember something about starting at the tip of a radial and working towards the feedpoint and using equal segment lengths and diameters in closely space elements but thats about it,

you will always see a tapered current distribution on antenna elements and radials,

your i10k table has equal currents and phase on all radials so in my minds eye good horizontal cancellation ( i could be wrong ) whereas your sp500 does not,

i expect symetrical equal length radials to have equal current and phase,
is that whats causing the current imballance and horizontal plot or not,
its just the first thing that entered my head, thats why i asked about the current table,

your sp500 table seems to show 2 pairs of radials with one pair having different current than the other pair as i imagined,

is that because of how you did the model or is it because the effective lengths of one pair are different to the other pair?,
i don't know and can't think of any other reason you are seeing the horizontal plot if you did not sellect a function in nec to show it,

can you tweak the model by lengthening the two radials on the bracket side by a few inches?
it would be interesting to see if that made the currents more equal or sqewed the horizontal plot,

you could also change two radials on the i10k to see if it causes the horizontal plot,

hopefully somebody that understands nec will show up and set us straight.

 

[Marconi]

i don't understand the phase table because i never looked into nec any further than a cursory peak, i remember something about starting at the tip of a radial and working towards the feedpoint and using equal segment lengths and diameters in closely space elements but thats about it, you will always see a tapered current distribution on antenna elements and radials,

I think you're right. Now I understand your use of the term "taper" when you used it in a previous post, you were talking about the current distribution being tapered.

your i10k table has equal currents and phase on all radials so in my minds eye good horizontal cancellation ( i could be wrong ) whereas your sp500 does not,

I think you are right again, but part of the problem with my SP 500 model, among other things, is the lack of symmetry in the mount. Your idea to lengthen certain radials has just such an affect. In the process of doing as you suggested, I noticed that the placement of the mast also affected this issue.

i expect symetrical equal length radials to have equal current and phase, is that whats causing the current imballance and horizontal plot or not, its just the first thing that entered my head, thats why i asked about the current table,

Well the fix I made to the bottom of the mount did not fix the horizontal pattern from showing, and the Average Gain for the model did not improved much. So there is still a problem. I understand what you were thinking now.

your sp500 table seems to show 2 pairs of radials with one pair having different current than the other pair as i imagined, is that because of how you did the model or is it because the effective lengths of one pair are different to the other pair?, i don't know and can't think of any other reason you are seeing the horizontal plot if you did not sellect a function in nec to show it,

If I selected such a function Bob, I didn't realize it. I think you'll see these two pairs of radials looking even more obvious now. I'm not sure that causes the horizontal pattern to show up, but I would bet it had something to do with it.

What looks to be radials in the lower flat part of the bracket was just my idea to simply connect the bottom of the radiator to the mount. I could have used just one wire to do that...and it would not look so much like radials. I was thinking if I used just one wire...then maybe the pattern would be skewed even more.

can you tweak the model by lengthening the two radials on the bracket side by a few inches? it would be interesting to see if that made the currents more equal or sqewed the horizontal plot, you could also change two radials on the i10k to see if it causes the horizontal plot,

hopefully somebody that understands nec will show up and set us straight.

View attachment SP 500 fixed mount .pdf

 

[Marconi]

Well Bob, here is an update on the SP 500 model.

I think I posted that I fixed the bottom bracket mount flange already. It ended up about a 1/4" inch smaller than the stock item on both ends, at 2.8" x 2.8", but maybe that's close enough. There are just too many wire attachments in the model for the mount area to try and fix, unless I was sure it really mattered.

I also added the top hat and made the radiator 22' feet using 4 x 6" radials, as per some recent installation reports for the new HyGain antenna. I'm not sure about the length of the top hat radials however. Nobody has come forward with any real measurements for this one, even though I've asked repeatedly.

As per what I think I learned recently working within a Cebik model, I also increased the segments. That put the feed point closer to the bottom mounting bracket where it belongs, and according to the Eznec book that can make the model more accurate. I think that is how I was finally able to lower the Average Gain = 0.856 = 0.67 db, but it is still not good.

The gain also dropped, and is still showing a little better than the I-10K. Of course this drop is probably due, in part, to the improved AG. The horizontal pattern is still present however.

Tomorrow, I want to try and get the radials set like the real antenna, but this means I'll have to move them out of the x and y coordinates. That makes my modeling more difficult. I don't think I can use the feature that builds radials. To be truthful, I just haven't fingered out yet how to do it...with four radial wire End #2 Coordinates, at four different points, floating out there in space somewhere. It's kinda' like trying to draw a picture using a magnifying mirror.

Here is the mount with currents turned off and a view of the new antenna.

View attachment SP 500 + Top Hat.pdf

 

[bob85]

it looks like a tricky antenna to model eddie, looking at pictures of the antenna and comparing it to the model id say the feedpoint needs to be down near the bracket with no wires between feedpoint and bracket,
i have no clue how to model the wide flat bracket, i think we need a necspert.

higher gain than the i10k :w00t:

 

[Marconi]

it looks like a tricky antenna to model eddie, looking at pictures of the antenna and comparing it to the model id say the feedpoint needs to be down near the bracket with no wires between feedpoint and bracket,
i have no clue how to model the wide flat bracket, i think we need a necspert.

higher gain than the i10k :w00t:

I'll get back on this tomorrow, but don't worry about the higher gain thing. You just didn't understand why I said that and I tried to explain. It's pretty simple, the current real gain for the SP 500 has to do with the high Average Gain being out of whack, and the lower that goes the lower the real gain will show too. I don't know how the gain comparisons between these two will work out in the end however, if and when I'm able to get the AG better, but I'd bet the models will be close as usual.

Maybe Henry or one of his buddies will step in and help us understand some of this.