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

[BOOTY MONSTER]

i'm gonna guess tha theres a few hams that have had difficulty learning to use the modeling programs too . so it's not just CB'ers that have problems figuring it out . some of you pork butts know more than us cb'ers for sure , but having a hammy ticket doesn't mean someone is brighter than someone that doesn't .

how does the imax with the maco or sloped GPK look compared to the new penetrator 500 .... they are in a similar price range .

 

[W5LZ]

The angle of those radials, the amount of 'droop', has little to nothing to do with it's radiation pattern or how it works that way. They do have a lot to do with the input impedance of the antenna, IF they are properly installed and are used for radials instead of a block for CMCs.
The antenna modeling programs are subject to limitations and errors. They make very nice 'indicators', but will never show exactly whats happening with an antenna without a huge amount of information plugged into it about all the 'stuff' around it. Otherwise, it's always going to be a 'best case' instead of 'real world'. They can get 'close' though.
- 'Doc

 

[Marconi]

i'm gonna guess tha theres a few hams that have had difficulty learning to use the modeling programs too . so it's not just CB'ers that have problems figuring it out . some of you pofk butts know more than us cb'ers for sure , but having a hammy ticket doesn't mean someone is brighter than someone that doesn't .

how does the imax with the maco or sloped GPK look compared to the new penetrator 500 .... they are in a similar price range .

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 that 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?

 

[gamegetter]

. It was an "attention getter.

Did someone say getter? LOL

Greetings Marconi: I hope today finds you well, sounds like you doing ok, trying to get some talk going!
As for me I thankful the slow moving front is passed at last and my bones ain't a hurting today.

I was wondering if I could talk you into producing the models you are talking about at only one height of 27 feet and with 2 ground plane configurations-45 degrees and horizontal.

My theory is that 27 feet above ground would be "around" optimal height and that either one of the 45 or horizontal
ground planes would be optimal for that height.

Mast included of course it's the best of 'real world' we could get with modeling.

If it's too much trouble or your opinion is different, then no problem. Best of luck.

 

[Marconi]

The angle of those radials, the amount of 'droop', has little to nothing to do with it's radiation pattern or how it works that way. They do have a lot to do with the input impedance of the antenna, IF they are properly installed and are used for radials instead of a block for CMCs.
The antenna modeling programs are subject to limitations and errors. They make very nice 'indicators', but will never show exactly whats happening with an antenna without a huge amount of information plugged into it about all the 'stuff' around it. Otherwise, it's always going to be a 'best case' instead of 'real world'. They can get 'close' though.
- 'Doc

Well 'Doc you're up to your normal pessimistic approach to any efforts posted. Of course this modeling idea would have to be duplicated in the real world in order to be sure, and then different areas may still differ.

If Tech 833, was in fact using a ligament antenna test range that showed the Imax with 30* degree angles were better than the way the GPK comes at about 45* degrees, and these models support that real world finding, then where is the problem that bothers you so? At least the models supports what (another) he has tested and reported.

Earlier I posted the link to his report right here in this thread, if you want to go take look at what he said. I even told a story about how I felt originally when he posted his report. I may have even questioned him about his claim years ago. I just recently read it again, and I decided to try and see what Eznec might suggest, and I was surprised, so here we are.

Are you just a complete Oklahoma hillbilly naysayer about everything?

Most of the guys on here are just curious about stuff, some are just trying to maybe explain what happens to them, and a few try testing and reporting their ideas. We aren't trying to solve the mysteries of life or the universe.

My modeling may just be a little bit better that quoting stuff we read on the restroom walls of a Truck Stop though, so if you have anything constructive to add to my modeling work, then lets talk about the details.

 

[Marconi]

Did someone say getter? LOL

Greetings Marconi: I hope today finds you well, sounds like you doing ok, trying to get some talk going!
As for me I thankful the slow moving front is passed at last and my bones ain't a hurting today.

I was wondering if I could talk you into producing the models you are talking about at only one height of 27 feet and with 2 ground plane configurations-45 degrees and horizontal.

My theory is that 27 feet above ground would be "around" optimal height and that either one of the 45 or horizontal
ground planes would be optimal for that height.

Mast included of course it's the best of 'real world' we could get with modeling.

If it's too much trouble or your opinion is different, then no problem. Best of luck.

I'm guilty of glomming on to part of your handle, is true. :sneaky2:

Gamegetter, can you give me a little nudge to the location of this model at 27' feet with the 2 ground plane configurations- 45 degrees and horizontal? I don't recall doing a 27' foot model in this thread.

 

[gamegetter]

my thought are based on something i read some time back on an article from the arrl handbook...for some reason i keep thinking that 3/4 wl above ground for an elevated ground radial system is supposed to be ideal in terms of the missing half of the antenna and on helping the feed point impedance,,,this related to voltage/high-current on the lower end of said antenna.

that having been said, the models could prove an ideal elevation and and ideal angle for the radials...

enjoy the rest of the evening sir, i have some mowing to do tonight and 'prolly won't be around til late tonight or 'morrow.

 

[BOOTY MONSTER]

Height versus take off angle

 

[wavrider]

i'm gonna guess tha theres a few hams that have had difficulty learning to use the modeling programs too . so it's not just CB'ers that have problems figuring it out . some of you pork butts know more than us cb'ers for sure , but having a hammy ticket doesn't mean someone is brighter than someone that doesn't .

Booty I have not even attempted to try to learn how to use a modeling program.

That is not to say I do not research the www and read about the graphs and how they relate to the different type of antenna's.

I will study the graphs then go build an antenna and see how it does.

As DOC said, the modeling is sort of like an "It may work like this" type of thing IMO. Have to take into consideration all the surroundings and the type of ground under the antenna. I think DOC said all this already.

I firmly believe, and have tested the theory of Height and TOA.

Three element at 75' I could work into Japan from Florida with no problem on 15 meters. The yagi is a Mosley TA-33.

The Mosley PRO67B has three active elements on 15 meters. It was at 45' in height and I could not even hear the JA station good enough to make a contact.

That 30' made all the difference.

I study Eddie's graphs and read Bob's comments, build the vertical and try it on 11 meters. If it works out on 11 meters then I build some for the other Pork Butt bands, and they usually work good there also.

Guess what I am trying to say is modeling has it's use and does serve a purpose, but it is not at all conclusive as to how that antenna will perform "on the air". That is why I like it that Eddie takes the time and effort to model his antenna's, then install them and compare them.

None of it is Scientific approved method, but then again I do not think any of us are scientists.

Just real world results with a real world effort put into the testing and evaluation. Thanks Eddie for all the time and effort you have put into this modeling and testing. I am learning from these threads, as are many others.

 

[W5LZ]

Marconi,
"Are you just a complete Oklahoma hillbilly naysayer about everything?"
No, there are no 'hillbillies' in Oklahoma. There are 'rednecks' though, and I was issued the #2 in the RedNeck club. I did the issuing so that has to be the way it is.
Having gotten that out of the way, I would like to say that I'm not the only one who thinks those antenna analyzer programs are nice, but they still have to be 'mixed' with some real world knowledge to come out even ball-park close. Would you take the word of the guy who wrote that EZNEC program that it isn't -exact- by any means? How about the writers of the NEC program that EZNEC was derived from? They will tell you the same thing, that their program requires a huge amount of real world data before it can even get close to real world numbers. The average person has no means of collecting that data because they can't do the measuring required. And that's why the results of the EZNEC and other derivitives of the NEC program are always given in dBi, or isotropic numbers. Another definition of that "i" could be 'ideal', for what you would get under ideal conditions/circumstances.
I have and use EZNEC. I've also got the base NEC program, and another one that's a quite a bit older antenna analyzer program. They DO give you some idea of what's possible! But they will never be as exact as some people think, they can't be that exacting except for 'isotropic' antennas in isotropic 'space'. There are a gob of 'fudge factors' built into EZNEC, or compromises based on real world experience. The newer the version of the program the more of those 'fudges' there are. Ever wonder why?
It's a nice program and I'm glad I've got it. But I've learned not to get too obsessed with depending on it.
- 'Doc

 

[Marconi]

Marconi,
"Are you just a complete Oklahoma hillbilly naysayer about everything?"
No, there are no 'hillbillies' in Oklahoma. There are 'rednecks' though, and I was issued the #2 in the RedNeck club. I did the issuing so that has to be the way it is.
Having gotten that out of the way, I would like to say that I'm not the only one who thinks those antenna analyzer programs are nice, but they still have to be 'mixed' with some real world knowledge to come out even ball-park close. Would you take the word of the guy who wrote that EZNEC program that it isn't -exact- by any means? How about the writers of the NEC program that EZNEC was derived from? They will tell you the same thing, that their program requires a huge amount of real world data before it can even get close to real world numbers. The average person has no means of collecting that data because they can't do the measuring required. And that's why the results of the EZNEC and other derivitives of the NEC program are always given in dBi, or isotropic numbers. Another definition of that "i" could be 'ideal', for what you would get under ideal conditions/circumstances.
I have and use EZNEC. I've also got the base NEC program, and another one that's a quite a bit older antenna analyzer program. They DO give you some idea of what's possible! But they will never be as exact as some people think, they can't be that exacting except for 'isotropic' antennas in isotropic 'space'. There are a gob of 'fudge factors' built into EZNEC, or compromises based on real world experience. The newer the version of the program the more of those 'fudges' there are. Ever wonder why?
It's a nice program and I'm glad I've got it. But I've learned not to get too obsessed with depending on it.
- 'Doc

Well 'Doc, one of these days I might get to be perfect too and fully understand the world around me.

Most of the models I mess with are pretty simple, and that should be easy for the software guys to handle the calculation necessary to reproduce what goes on with these simple CB type antennas, plus the calculations have been around for a long long time, and I'm pretty sure they have been fine tuned, and I know the process for doing the math has been speed-ed up considerably by the application of the math to the personal computer.

So, until somebody can put me straight to how much difference these models show compared to what only God really knows, I'll continue to produce them as some evidence, right or wrong, for what I see and do.

Now if en' when I get to seeing a 1/4 wave whip, showin' me a pattern that indicates a 11.55 dbi gain on the horizon, maybe then, I'll draw up with a plug of Days Work, and start to ponderin' my work again, as I holler, "Spittttttt" to my buddies riden' in the back of my pickem' up truck.

 

[W5LZ]

Good for you, knock your self out with it...
- 'Doc

 

[Needle Bender]

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.

 

[gamegetter]

yes, NB...but trying to find some 'indication' of an angle that may improve match, thereby adding efficiency to system which "should" add to gain on the horizon where we want it is Marconi's drive.

To all I say the models are all we have, we know they are not perfect and that everyones installs will be different in the real world. But science is about continually testing the theories and observations. We will always be doing it and others will always test the observations we leave behind.

Marconi knows what he is looking for and if along the way we can help him with some information then great! The results may be enlightning they may not. Nothing ventured nothing gained.


Now that having been said, i think that a systematic approach should help. First let's get a model that establishes the best theoretical height if we are going to use a sort of real world model with mast for THIS antenna (Marconi you mentioned the 1/4 wave above and that should be modeled separately in my thoughts) I have suggested 3/4 wl above ground as the best for supplying the bottom half of missing antenna with an elevated ground plane system,..

The other option is to model in free space, which is ok, but then we are left with trying to duplicate that on the ground, ie isolate antenna from mast, decoupling and etc

But to me real world with mast is best way to go.
"Good Day"

 

[Needle Bender]

Anecdotal; Steve used to live in town and before his move to the hills he ran an Imax on a 27' telescoping push-up mast from the ground and had one heck of a strong signal and great receive even though he didn't live on a hill, more toward the bottom of a small one.