Marconi's Eznec5 model - Imax with radials at various angles.

[gamegetter]

i have experienced what i thought were good results at about that elevation my self but only today am I trying to put 2 and 2 together and with Marconi's models may be able to add a hint of credibility to this.

that height is quite possibly important to further test the angle of the ground plane theory we are after.

Marconi is this enough 'nudging' ? or nagging if you like...If i fail i fail alone, nothing ventured nothing gained at the school of hard knocks.

 

[Marconi]

Yep BM, I could have included hams too, but my point in saying that was to draw attention. It was an "attention getter."

I'm going to redo those test, Marconi's Eznec5 model - Imax with radials at various angles, just because I found that the face model with horizontal radials was in error with the radial length. I made it with 62" radials instead of 72" like the original GPK comes. I don't know if I made further mistakes in the models I posted, but I know all the dimensions I used for the recap work were done one steps at a time at 40', 65', and 36' feet using the exact same model each time. I just posted those 4 Eznec models to kind of support what I showed in the recap report.

I don't think this will make much difference in the results, because the model with horizontal radials is better when corrected than the model I posted, so the result differences are probably even more obvious when using horizontal radials on the Imax.

I don't know off hand how the models for the Imax and SP400 differ, but if I can think of it, I'll check that for you. I never did get my model of the SP400 with a working matching device included...to working right, so I'll compare a regular 5/8 wave ground plane at 22.5' model instead, and we'll see what Eznec says about it, OK?

Well guys the quote above is a post to BM where I told him about the model error I found with the original model I posted at the beginning of this thread. I fixed the radial length error I made to the model entitled (.625 wave x 105" radials 40') with 4 horizontal radials at 62" instead of 72". It was just a fluke error I made.

You will note that the model improved and this model shows to be even better, at 40', better than all the models with slanted down radials at the same height. This was my whole point in this model, to show the difference, and not show a best installation idea for the Imax. Only real world testing can prove that.

BTW, the recap report I posted in the beginning (my post #6) is still the best source of data that I did for this project.

Here is the new model, and I've added the currents tabular data to maybe help me explain what I see going on with the phase and currents for NB that might help us understand the cancellation ideas we think about with the 5/5 wave antenna. I added some notes that maybe will help in that understanding as I see it.

View attachment .625 wave x 105''radials 40'.pdf

 

[gamegetter]

105" or 72" radials

cmc's look much better, a feed line isolate(not a mast isolate) would take care of that by person doing the install if he wanted too.

I can't help but to think that the model could be duplicated with the stock 72" radial by finding the right height. My thought is that the # of lobes would be reduced and the gain refocused on the horizon.

 

[BOOTY MONSTER]

why would non-resonate GP elements perform better than resonate ones ?

 

[Marconi]

I'm not surprised with the results at all. If the radials on a 5/8 are an extension of the lower inverse phase sine wave current, then keeping them in the horizontal polarization seems like it would provide the most vertical to horizontal attenuation/cancellation of that unwanted inverse current - is my best guess.

NB, I hope the corrected model I just posted above will help us understand how the currents are working in this 5/8 wave model. As I see things, this does not conflict with the theory as I understand it.

So, I added the currents tabular data report for you to check out. The sign of the phase indicates whether the currents are in-phase or not and I marked the report accordingly. You will notice that the bottom part of the radiator is out of phase with the top 1/2 wave portion.

It is my opinion that the radials are in-phase with the top of the radiator, but due to the currents running in the opposite direction in the radials...their horizontal RF is mostly canceled. This also agrees with theory, as I understand it.

 

[gamegetter]

why would non-resonate GP elements perform better than resonate ones ?

BM, I saw a hint of this possibility on post #6 where Marconi posted his pdf of findings for different length radials.

Not taking it out of context is I think important...the shortened ground planes in conjunction with the right height could possibly give the same outcome.

Just my thoughts, but I have no way to prove it.

 

[Marconi]

cmc's look much better, a feed line isolate(not a mast isolate) would take care of that by person doing the install if he wanted too.

I can't help but to think that the model could be duplicated with the stock 72" radial by finding the right height. My thought is that the # of lobes would be reduced and the gain refocused on the horizon.

Gamegetter, you're right the CMC on the mast are much better. That was due just to my making the radials 72".

I did a 102" version in the recap report that I posted on post #6, and I show the currents as a side note. So, maybe you can see a little of that difference indicated as good, bad, and medium, which is just my looking at the red lines on the Antenna View and making a judgment for what I saw.

Regarding your feed line and the mast isolation ideas, I tend to think if we can effectively stop the CMC from flowing on the feed line using a choking device, then that will also help prevent currents on the mast.

I'm not too sure however, that I fully understand your last point, so maybe you could help me with that one.

 

[Needle Bender]

NB, I hope the corrected model I just posted above will help us understand how the currents are working in this 5/8 wave model. As I see things, this does not conflict with the theory as I understand it.

So, I added the currents tabular data report for you to check out. The sign of the phase indicates whether the currents are in-phase or not and I marked the report accordingly. You will notice that the bottom part of the radiator is out of phase with the top 1/2 wave portion.

It is my opinion that the radials are in-phase with the top of the radiator, but due to the currents running in the opposite direction in the radials...their horizontal RF is mostly canceled. This also agrees with theory, as I understand it.

Foggy... I'm not seeing how the radials could be in phase with the top since they are at DC ground with the inverse phased mast, fed by the same RF current phase as is the mast

 

[Marconi]

why would non-resonate GP elements perform better than resonate ones ?

BM, I can't be for sure, but I tend to think the importance and length of radials on certain antennas depends on how much the antenna needs radials, and how close they are to a current source.

The 1/4 wave really needs radials, so 1/4 wave radials tends to work best.

For me a 1/2 wave hardly needs radials at all, and they are typically positioned far away from a current source so maybe this is why we hear stories that radials don't seem to show a difference.

The 5/8 wave is about in between the 1/4 and the 1/2 wave in this regard, so generally less radial affects will do, with maybe some exceptions. My experience with my I-10K proved to be an exception. I removed the two end pieces of its radials and the antenna's match went to pot.

Why the difference between this Imax type and the I-10K, I can't say for sure, but I do have an idea. It has to do with the way the Imax tuner balances the feed point currents around the capacitor.

<gotproof> This idea is not mine, and is better explained in the Yates link I posted on this thread, as the genesis for this project. I think there is a picture in his article describing this balance idea.

 

[Marconi]

Foggy... I'm not seeing how the radials could be in phase with the top since they are at DC ground with the inverse phased mast, fed by the same RF current phase as is the mast

All I see is what the currents indicate on the tabular list. If two element show the same phase, they produce some radiation, relative to the magnitude being equal as well. The less similar the magnitude the less RF generated by in-phase elements. On the list, this phase thing is noted by the sign (= -).

NB I hate to mention this regarding Sirio, because I think I recall you having issues with Bob on this issue, and maybe it was all about what their software was revealing to me, Bob, and others.

But, if we could see currents, we probably wouldn't be discussing this. So, if you look again at the Sirio stuff on the Gain Master, maybe you can see better and maybe understand better what is going on. If I'm right, it all looks clear and simple to me.

IMO, this is all because Sirio's Software shows these currents animated, in such a way as to reveal phase and no-phase, and they do it in color and shape...that suggest current magnitude a little.

Also check the mast currents, the mast has various phases in its length.

 

[gamegetter]

Gamegetter, you're right the CMC on the mast are much better. That was due just to my making the radials 72".

I did a 102" version in the recap report that I posted on post #6, and I show the currents as a side note. So, maybe you can see a little of that difference indicated as good, bad, and medium, which is just my looking at the red lines on the Antenna View and making a judgment for what I saw.

Regarding your feed line and the mast isolation ideas, I tend to think if we can effectively stop the CMC from flowing on the feed line using a choking device, then that will also help prevent currents on the mast.

I'm not too sure however, that I fully understand your last point, so maybe you could help me with that one.

I was thinking the last model you posted was with 105" radials, but i see now from your comments here that it is for the stock 72" radials, so then for sure the 72" radials at 40' are looking pretty good at this point, and that is what I was thinking that the stock 72" radials can yield some good results but with the right elevation...Perhaps a 27' mast height may help may be not(that based on my previous conjecture of 3/4 wl above ground),,,

Other wise at this point you could take the model to 45 degrees on the radials and see if that improves the model. If it does then taking it to 70 degrees would be my next step and see what it does from there.

Hope you follow my thoughts, other wise let me know I will try to be clearer when I type.

Have a good afternoon.

 

[Marconi]

I was thinking the last model you posted was with 105" radials, but i see now from your comments here that it is for the stock 72" radials, so then for sure the 72" radials at 40' are looking pretty good at this point, and that is what I was thinking that the stock 72" radials can yield some good results but with the right elevation...Perhaps a 27' mast height may help may be not(that based on my previous conjecture of 3/4 wl above ground),,,

Other wise at this point you could take the model to 45 degrees on the radials and see if that improves the model. If it does then taking it to 70 degrees would be my next step and see what it does from there.

Hope you follow my thoughts, other wise let me know I will try to be clearer when I type.

Have a good afternoon.

Let's do them one at a time, OK? I can make the mast for the model (.625 wave x 105" radials 40') 27' feet in just a couple of key strokes. Is that the first thing?

Let me know if this is what you would like to see first?

EDIT:

BTW, this just dawned on me gamegetter. I've been working on two projects at the same time regarding the Imax. Is it possible that I got some of my post mixed up between those two projects? One has to do with radial angles, and the other has to do with radial lengths.

Anybody that is confused on this please let me know so I can try and fix the issue.

 

[gamegetter]

I got it sorted out Marconi from your data sheet post #6. I have printed everything out and am following you just fine.
Others can post up if they need clarification.

What I am interested in would be the stock 72 inch Imax radials on the Imax (.625wl) at about 27 feet height mast and feed line included in model. We could start horizontal, then 45 degrees then 70 degrees on the radials angle to see if there is any improvement.

Of course the first model at horizontal radials should tell us alot and whether we would even want to do the other iterations.

I am hoping to see a reduction in lobes and more gain on the primary. Ideally for me would be to see only two lobes.

Let me know what you think on this or if I need to clarify anything before you proceed to running any models.

Thanks for your help and time. Good Day.

 

[Marconi]

I got it sorted out Marconi from your data sheet post #6. I have printed everything out and am following you just fine.
Others can post up if they need clarification.

What I am interested in would be the stock 72 inch Imax radials on the Imax (.625wl) at about 27 feet height mast and feed line included in model. We could start horizontal, then 45 degrees then 70 degrees on the radials angle to see if there is any improvement.

Of course the first model at horizontal radials should tell us alot and whether we would even want to do the other iterations.

I am hoping to see a reduction in lobes and more gain on the primary. Ideally for me would be to see only two lobes.

Let me know what you think on this or if I need to clarify anything before you proceed to running any models.

Thanks for your help and time. Good Day.

OK, gamegetter, hopefully I won't be using the (.625 wave x 105" radials 40') any more on this thread. I'm using the model entitled "Imax 40' GPK mast horizontal", you see below. It is a bit different than the model I used in the Recap on page #6, but I think we'll find the results will be close.

The reason I changed the model is because I decided to "Cebikize" the model where all of the segments are very close to the same length etc. When I do that to most of my models the gain figures tend to drop just a little, which we might expect...as the model becomes more accurate.

I will also try and keep the wire number indicated on the Antenna View showing the antenna height, and I will indicate using notes for the radial lengths, and add to the caption the angle and height for the model. Hope this is clear. This is for consistency in the project, which I sometimes miss and where it can get confusing for the reader, like you noticed. During this process here, I've learned a new lesson which I must watch more closely in producing my models.

I will change the height to 27' feet and post it below to start. Then I'll wait for you next ideal, OK?

Here is my new starting model at 40' feet and I will then use just this model in your ideas for different iterations, OK?

View attachment Imax 40' GPK mast horizontal.pdf

 

[gamegetter]

sounds good, hope it will produce some good information.