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

[Marconi]

1st Imax iteration with starting model and recap.

You'll notice that the currents got much better, maybe improved enough so we might not even have to consider isolation.

Here is the 1st model, and recap. Then the model lowered to 27' feet with an overlay of both models. Do you also want to track the match and see how height affects these changes. I could add the source data.

Too bad the recap coppied upside down.

View attachment Gamegetter's Imax ideas..pdf

 

[Marconi]

Gamegetter, I forgot to say I didn't model the feed line like you requested. I might try that today and see if it makes any difference to the model.

I suspect that if I didn't have the mast included then adding the feed line would make a difference.

 

[gamegetter]

Yeah but that is doing what I was thinking, improving signal on the horizon by reducing the sky warmers.

Adding mast and feed line would be good as most folks will install as such and that info needs to be considered(but there is good hope for a proper isolated install-i think)

I will let you work on that before suggesting the radials be lowered to 45 degrees from horizontal.

P.S. summary sheet was to light to view.

thanks enjoy the day.

on edit: be nice to see the match

also if the models show it in the end then most folks could install with a push pole and have good results, no need to go to extra height.

what do you think?

 

[Marconi]

Yeah but that is doing what I was thinking, improving signal on the horizon by reducing the sky warmers.

Adding mast and feed line would be good as most folks will install as such and that info needs to be considered(but there is good hope for a proper isolated install-i think)

I will let you work on that before suggesting the radials be lowered to 45 degrees from horizontal.

P.S. summary sheet was to light to view.

thanks enjoy the day.

That summary sheet was the recap that I forgot was in back of the first model. You already have that from post #6.

The isolation of this model at 27' does not look too good. It lost some gain and the currents on the mast increased some in spite of the 6" gap I made between the antenna and the mast.

View attachment Gamegetter's 27' foot idea isolated..pdf

 

[gamegetter]

one good model and one not so good at 27'

i say stay with the good one, (the first one) and then turn the radials to 45 degrees from horizontal. If that looks better we could try 70.

thanks again for your help.

 

[BOOTY MONSTER]

has anyone been able to confirm that the 72 inch imax radials have one straight length of wire in it ?
and that it's not a 1/4 wave antenna helically wound like typical mobile fiberglass antennas ?

 

[Marconi]

one good model and one not so good at 27'

i say stay with the good one, (the first one) and then turn the radials to 45 degrees from horizontal. If that looks better we could try 70.

thanks again for your help.

Ok, here is iteration #3, 27' with slanted radials 72" @ 45* degree. Note that max angle, gain, went up, and currents increased a bit.

If you can, check real close at all of the angle changes between the two, slanted and horizontal, the total lobe that is at beneficial angles for CB probably got better with slanted radials, and the maximum gain went up a bit at a higher angle, so check what happens at the bottom of the patterns close to the horizon and you will see that the pattern for slanted also raised up a little and there the gain was a bit lower than the horizontal pattern.

This is find distinction, and I don't see this making a bit of difference that we could tell using our radios, but the difference is not so obvious unless you check carefully. The only point for doing so might be to give us and idea for the trends that is going on here. Trends, rather than absolute accurate models is what I try to glean in these models.

View attachment Gamegetter's 27' foot idea isolated. #3.pdf

 

[Marconi]

has anyone been able to confirm that the 72 inch imax radials have one straight length of wire in it ?
and that it's not a 1/4 wave antenna helically wound like typical mobile fiberglass antennas ?

BM, very good question.

I could answer this in a minute, but I'm going to wait and see if anybody on this forum can figure this one out, and tell us the answer and how they found it out.

This is one of Marconi's challenges.

 

[BOOTY MONSTER]

found a article about the imax that i haven't seen before ... thought y'all might find it interesting .

Solarcon I-MAX 2000 Antenna - K3DAV - Amateur Radio Operator

nice pics of the GPK

Foxtrot Bravo Discussion Forums :: Antennas :: MFW Imax 2000 with straight radials - photos! ~ Runboard

tech 833's review of the Imax 2000 Ground Plane Kit

Copper Talk

IMAX 2000, Antenna Comparision

 

[Marconi]

Gamegetter, here is iteration #5. It is #4, that I isolated 6".

I also have an overlay for iterations at 27' - #2,3,4, here:

View attachment Gamegetter's 27' models 2,3,4..pdf

I forgot to mark the 6" isolation point, but you can see it clearly below the antenna. One big thing I noticed is that the 30* degree and the horizontal don't seem any better than the original Imax GPK at 45* degrees at 27' feet. Unlike what I reported for the GPK at 40' feet. Surprises all the time.

View attachment Gamegetter's 27' model at 30 degrees ISO.pdf

You mentioned maybe 70' feet next. What is so significant about 70' feet?

 

[gamegetter]

Greetings:

Nothing at 70 feet. The 70 i mentioned was for angle of radials from horizontal to see if the Astro plane/Top One configuration would be of use to this model. However, and now that you mentioned it if you are looking for another height to try for the sake of testing and as you would say to add (or subtract LOL) to the "trends", i would try 54 feet. My only reasoning for that height would be that it is twice the 3/4 height of the wl we are playing around with(.75x2=1.5, and 1.5x36'=54). Just some food for thought for a later project which happens to be one I am working on with a new tower-so many projects, so little time.

All that is well and thanks for the iterations. For my purposes you have helped me out quite a bit and i agree with what you say!
This surprise is welcomed by me! It may not work for all as you and everyone is well aware.

I would not expect my 70 degree theory on the radials to help out the model any, but if you want to give her a try, then that would be good...At that point we have left no stone unturned with this model at this elevation.

Thank you my friend I appreciate your work. I will try to check in periodically. Having a busy day today.

"Good Day"

 

[Marconi]

Greetings:

Nothing at 70 feet. The 70 i mentioned was for angle of radials from horizontal to see if the Astro plane/Top One configuration would be of use to this model. However, and now that you mentioned it if you are looking for another height to try for the sake of testing and as you would say to add (or subtract LOL) to the "trends", i would try 54 feet. My only reasoning for that height would be that it is twice the 3/4 height of the wl we are playing around with(.75x2=1.5, and 1.5x36'=54). Just some food for thought for a later project which happens to be one I am working on with a new tower-so many projects, so little time.

All that is well and thanks for the iterations. For my purposes you have helped me out quite a bit and i agree with what you say!
This surprise is welcomed by me! It may not work for all as you and everyone is well aware.

I would not expect my 70 degree theory on the radials to help out the model any, but if you want to give her a try, then that would be good...At that point we have left no stone unturned with this model at this elevation.

Thank you my friend I appreciate your work. I will try to check in periodically. Having a busy day today.

"Good Day"

OK, I'll try the 70* degree angle below horizon.

The 70' foot height idea that I thought you were talking about...showed similar trends as previously noted at 27' feet. The 72" horizontal radials made a .50 dbi gain advantage over the slanted down radials.

That's not much, but maybe this is why Solarcon uses the shorter radials, I just don't get why they have the GPK, with slanted down radials though. Maybe it looked better to the ad group.

With 72" radials slanted at 70* degrees the advantage seemed to start getting better again, with 5.37 @ 5* vs. 5.41 @ 5* degrees for the horizontal radials. So, this affect for various radial angles on the Imax at these heights are not linear.

For example: I post a similar model to the one above, except it has radials 109" instead of 72". Look what happens here.

I also post my notes for this 70' foot high test at different angles, and at 40' feet I did earlier.

View attachment Gamegetter's Imax ideas..pdf

View attachment Notes 052512.pdf

 

[gamegetter]

but maybe this is why Solarcon uses the shorter radials, I just don't get why they have the GPK, with slanted down radials though. Maybe it looked better to the ad group.

I have been asking myself this since yesterday on the solarcon/imax slanted ground planes....

I'm not liking the change in pattern on the 70 degree radial slants at 70 feeet for my use any way, would prefer to see the three lobes and better with 2 lobes in my opinion in the model-Perhaps the 70 degree slant radials will be better on the 27 foot height model.

it's all good information to have.

 

[Marconi]

I have been asking myself this since yesterday on the solarcon/imax slanted ground planes....

I'm not liking the change in pattern on the 70 degree radial slants at 70 feet for my use any way, would prefer to see the three lobes and better with 2 lobes in my opinion in the model-Perhaps the 70 degree slant radials will be better on the 27 foot height model.

it's all good information to have.

I don't believe we have much control over the lobes that develop on an antenna as we raise it up more lobes are produced, and longer radiators may add to this addition of lobes.

I didn't save any of the 70' foot high stuff except the one with 109" radials for another guy, but here is a pattern view of this model at 27' feet and it does have fewer lobes, due to remarks above, but you won't like it either, seeing as your first idea at 27' with 72" horizontal radials shows 3.44 dbi gain at 10* degrees vs. this last one at 1.44 dbi at 10* degrees.

That was good work, thanks for working with me.

View attachment Gamegetter's last model..pdf

 

[gamegetter]

I agree but I at least like to have the information.

This was a good lesson, thank you.