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Jo-Gunn 5 or 6 Star

BJ radionut said:
http://www.jogunn.com/images/jg6-star.pdf

Instruction manuals are on-line...this link is the 6 element version...

Having had one of these years ago and then a 5 Element Mosley....
The Mosley is with-out a doubt Hands Down...better built and better gain IMHO

To my HO ....Mosley is STILL the best around...
All the Best
BJ
Click to expand...

Thanks for the link BJ, but as I suspected, Jo Gunn does not included dimensions in their instructions. To get close with modeling, as in the real world, it probably is best to use accurate dimensions.

I also suspect that Jo Gunn's are probably fixed design, and there are probably few moving parts. For sure the spacing is fixed and I think the elements are pre-drilled for length except for the tips maybe.

I did a model of a Maco M103, and then removed the bottom elements. I added two slanted down radials like a JG, and there is a difference as noted above, but I doubt you would ever notice the difference just using a radio.

I don't know of a way to really determine the polarization differences using modeling per'se, but I did see the ground gain noted with horizontal polarization in both models, and again there was just a little difference with the advantage going to the standard design. So I don't think to say the JG design shows little or no horizontal polarization is quite accurate.

Here are four models, the M103 horizontal, M103 vertical, M103 with slanted radials and horizontal, and the M103 with slanted radials and vertical.

Again, I do not have JG dimensions. These models are comparing a Maco with a JG Star design. This could make some difference, for sure since the Maco looks to use optimized spacing. I think the JG uses more balanced spacing along the boom using older style designs, which in my opinion has some technical advantages over optimization also. Just my real world experience though.

View attachment M103 modeled like a JoGunn.pdf
 
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Thanks for taking the time to model that Marconi. The results were similar to what I expected with the vertical side showing more of a loss in the model due to what is essentially half of the element missing. Another interesting thing is that also removed energy in the 14 degree TOA while it made the useless 33 degree lobe strong enough to become the primary lobe.

The decrease in gain on the horizontal side is far less noticeable in the model because bending the radials down on a 45 still allows them to benefit from most of the ground gain and does not distort the pattern badly. On the other hand the problem would be very apparent if you started going beyond 45 degrees. The key here is that EZNEC does not appear to show you the loss in gain in a given plane.

The only difference it sees with polarization is related to the added ground reflection from being horizontal. We all know if you're listening to someone that is vertical and you switch to the flat side, their signal drops out. This loss has nothing to do with antenna gain and does not show up in the model. This is all about matching the polarity of the station on the other end to achieve maximum signal. It's not that the Jo-Gunn has little to no horizontal polarized signal. It obviously has no horizontal elements and tilting them 45 degrees away from horizontal will cause a 3db drop to horizontal polarized signals as a result.

Even before you go this deep into trying to determine loss in a given plane, it still should be easy for you all to see from these models that Jo-Gunn fabricates all specs and has totaly lied to us about the antenna having any advantage. Even the simple model shows it as a loss compared to a standard Yagi and that's before you factor in loss of signal due to cross polarization.
 
Shockwave, just to test my words suggesting that the previous models were using the optimized dimensions of the M-103C, I fixed the model using a balance distribution of 65" across the same boom. IMO, this is probably closer to what JG uses in their design idea. I did nothing else to the model.

This model now shows an improvement in gain for the non-optimized JG styled model from 5.75 dbi at 9* degrees, to 7.37 dbi at 10* degrees. This is also what I imagined when working my real world multi-element beams in the past, the balanced Moonraker boom element distribution worked best for me.

I did not rename the model for this example.

View attachment JoGunn dimensions simulated.pdf
 
I have a friend that uses a gizmotchy which is basicly the same antenna design. It does send a better signal when we are both on the same polarity be it vert or horz so it does work but I cant see how they would work better than a regular yagi. If anything happens to my maco I would like to try a dual polarity mosley but I dont think they still make them. I called them a few years ago. I guess I need to check again.
 
High Voltage Mobile NJ said:
hello greentiger . dont listen to this nonsence . there is nothing wrong with a Jo Gun Beam at all !!!!!!!! there is awsome technology in that Beam !!!!!! you put a jo gun beam up and it will not fall down . you put a maco beam up , lol lol lol and bye bye bye bye in the wind it will fly like a kite when you get a 75 mph wind storm . the gain on a jo gun beam is amazing and they out perform alot of antenna's out there .
Click to expand...


I sent you a Personal Message High Voltage.
 
Mr Clean said:
I have a friend that uses a gizmotchy which is basicly the same antenna design. It does send a better signal when we are both on the same polarity be it vert or horz so it does work but I cant see how they would work better than a regular yagi. If anything happens to my maco I would like to try a dual polarity mosley but I dont think they still make them. I called them a few years ago. I guess I need to check again.
Click to expand...

Anything made by Mosely is good but wow, boy oh boy, hold onto your wallet!!! If you think Jo Gunns are pricy you 'taint seen nothing yet!!:D
 
I just downloaded the Jo-Gunn catalog and to me it reads more like a comic book than a technical brochure. In over 40 year I have never seen a company so aggressively mislead their customers before. Their publications have your reading one blatent lie after the next as if no one would know. They even fabricated a new antenna specification called "Audio gain" so they could pile on more BS and promptly gave themselves 30db of this new gain. I'm not even going to ask how one measures this. Just know when a antenna manufacturer starts talking about improving your audio, start thinking the BS is just about up to your nose and run.

Then we have a 36 foot boom with a whopping 125 times power multiplication!!! Compared to what? The boom is like 5 feet short of reaching this gain over an isotropic radiator never mind gain over a dipole. How about the "V" series that claims to be circular polarization? It's not even remotely possible to form CP with all of your elements inline, in the same plane. They claim their Son of a Gunn 3/4 wave ground plane is the best. Model that jewel in EZNEC and you'll see it's the best at talking upwards with little energy on the horizon. The simple vertical dipole will out talk it every time (except to airplanes, space ships and Martian's).
 
Shockwave said:
I just downloaded the Jo-Gunn catalog and to me it reads more like a comic book than a technical brochure. In over 40 year I have never seen a company so aggressively mislead their customers before. Their publications have your reading one blatent lie after the next as if no one would know. They even fabricated a new antenna specification called "Audio gain" so they could pile on more BS and promptly gave themselves 30db of this new gain. I'm not even going to ask how one measures this. Just know when a antenna manufacturer starts talking about improving your audio, start thinking the BS is just about up to your nose and run.

Then we have a 36 foot boom with a whopping 125 times power multiplication!!! Compared to what? The boom is like 5 feet short of reaching this gain over an isotropic radiator never mind gain over a dipole. How about the "V" series that claims to be circular polarization? It's not even remotely possible to form CP with all of your elements inline, in the same plane. They claim their Son of a Gunn 3/4 wave ground plane is the best. Model that jewel in EZNEC and you'll see it's the best at talking upwards with little energy on the horizon. The simple vertical dipole will out talk it every time (except to airplanes, space ships and Martian's).
Click to expand...

For years I have heard repeated JoGunn's BS, but I never paid it no mind, just like I am not persuaded by anybodies advertising.

I never trusted their hype. That is why some years ago I bought an I-10K just to see what all the high gain hype was all about. More recently I did the same with the Gain Master, and a few others. I saw differences, but they were never like I heard suggested by others.

Shockwave, I don't think it comes as a surprise to you, but all advertising pushes the envelope in the puffing category.

A while back I modeled the basic design (absent the true dimensions) for the Son of a Gunn, and I find what you suggest, albeit is not quite as bad as you describe...as only radiating to the birds.

I wouldn't buy any JoGunn antenna however, just for the reasons you note. Mainly because they do not divulge any real information about their products, even to their own customers...excepting as you note just more BS.

I have modeled my sketchy ideas for several of their designs and after comparing what I find to some of their competitions models, I find them always lacking in some small ways...and for sure they are not equal to the hype they spew to the public.

After all this time of comparing antenna responses at my location, I still am convinced that my Starduster antenna is just about as good as any that I've ever had up. Even after more than a year comparing it to my Gain Master, I find very little difference in the scheme of things, and my Starduster is lower at the tip by about 6 feet.

There is nothing special about JoGunn antennas.
 
High Voltage Mobile NJ said:
hello greentiger . dont listen to this nonsence . there is nothing wrong with a Jo Gun Beam at all !!!!!!!! there is awsome technology in that Beam !!!!!! you put a jo gun beam up and it will not fall down . you put a maco beam up , lol lol lol and bye bye bye bye in the wind it will fly like a kite when you get a 75 mph wind storm . the gain on a jo gun beam is amazing and they out perform alot of antenna's out there .
Click to expand...

I have to agree. I had a 6 element Cross Jo Gunn up for 14 years. It survived a major ice storm a wind storms with 70 to 85 mph wind gust with no damage. I would have to say that the 4 element Shooting Star that the Jo Gunn replaced would not have faired nearly as well. There is one point about the Jo Gunn I didn't like and that was that it was a lot heavier than the Shooting Star. Performance wise the Jo Gunn won hands down.
 
You really have to compare similar antennas to see who's design is best. Comparing a 6 element that has a boom almost twice as long as a Shooting Star is not fair. As you note, the Jo Gunn is constructed well with heavy duty parts but I've seen two Lazer 400's hold up to every storm that's hit the East Coast in 30 years.
 
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I have not modeled a JoGunn beam, because I don't have a manual, and I'm not sure if I did it would be enough to really get it close. I doesn't look that complicated, but it is a little different I think.

Does anybody have a JG that could copy me their manual. I don't thing the JG is as bad as portrayed here, but I think I know it is no where as good as JG tells us either.

I have a model about done comparing the M103c, at 42' feet vs the Gizmotchy 3, at 42' feet...with both set vertical and horizontal. I'll post them soon, I think the JG Star design is similar to the Gizmotchy, but I need the dimensions for JG to be sure.

The horizontal M103c does show a better gain than the horizontal Giz by a little over 1.26, with both at 12* degrees maximum angle at 42' feet high. The Giz does have a shorter boom however. The free space models are very similar I think and much closer together in gain.

I'll do a recap for all 4 models and post soon, I just have to make sure they are apples = apples.
 
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My only gripe about the Jo-Gunn is they claim to have a gain advantage over the competition when in reality they have a slight disadvantage over all Yagi designs on the same length boom. The Gizmotchy you have modeled does use the same design elements as the Star series and as you see they come up short of the competition, not ahead.

The one area they may be good in is placing a signal in more than just a linear polarization. Since the elements are positioned in this 3 point star, there is some coverage in the vertical plane and the 45 degree downward slope gets some coverage in the horizontal.

The problem here is they have misled you into thinking this is anything like real circular polarization. Something this model could never produce in a thousand years. What they fail to point out is you can get real CP with antennas like a Shooting Star for a third of the money and just spend about $20 extra making some phasing cables.
 

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