Son of a Gunn

[Marconi]

I agree with Duster AVOID this antenna,And in response to the other comment yes Power hungery does describe operators in this area including me,I just want to be loud local so i should reverse the angle of the ground plane elements to have a low angle of radiation for local contacts?? Once again thanks 4 all the help...

Well Jgar, I flipped the radials up about 30* degrees on the model, and Bob is right the pattern does set the maximum angle much lower, but it may be better if slanted up even higher.

I would suggest you first get the JG working as intended, and then make the radials switch. You'll likely have to re-tune. This way you'll know it works, and you'll have something to compare.

 

[Robb]

Well Jgar, I flipped the radials up about 30* degrees on the model, and Bob is right the pattern does set the maximum angle much lower, but it may be better if slanted up even higher.

I would suggest you first get the JG working as intended, and then make the radials switch. You'll likely have to re-tune. This way you'll know it works, and you'll have something to compare.

Yep.
And if the radials go up even higher of an angle, it will start to look like a Sigma 4 as well as work like one too.
lol!

 

[bob85]

eddie,
try the upswept radials steeper, 30 degrees from the vertical or about twice the angle of the sigma4, you may have to extend the vertical a little as the resonant frequency should go up as you move the radials closer.

 

[Marconi]

eddie,
try the upswept radials steeper, 30 degrees from the vertical or about twice the angle of the sigma4, you may have to extend the vertical a little as the resonant frequency should go up as you move the radials closer.

Here it is Bob, the JGSOG radials close to 30* degrees slanted up. It helps lower the max lobe pattern much lower than the stock JGSOG, but there still seems to be a lot of high lobe angle that would waste power. I didn't mess with the radiator length, because the match is already too high to see a lower SWR. I might try it, but I doubt the pattern will change much. I might see is a bit of increase in gain though.

Sorry Robb, I don't think the pattern shows the JGSOG will do quite like the S4. The trend may be the same, but I would suspect this has a lot to do with how the loop functions on the S4, or maybe it needs a higher slanted angle. I don't believe I ever tried the S4 without its hoop. Just a guess, but that might tell us whether it's the hoop or the angle that makes the difference here.

View attachment FreeCell Bob's idea .75w.pdf

Here is my S4 model I did last year also set a 36' feet.

View attachment Sigma 4 052711 @ 36'.pdf

 

[bob85]

the pattern is going in the right direction eddie, i don't like all that current in the mast/coax on either model, it looks like a worst case scenario,

maybe with some tweaking of element lengths and isolating the mast/feedline it could work like a sigma4,
avanti never said the hoop improved anything but bandwidth,
i don't think the wider angle they talk about in the patent included a hoop,

thanks.

 

[Mudfoot]

JGAR SON OF A GUNN

Product #:1005190

Description:
FREQUENCY RANGE: 26.000 - 29.500

*GAIN: 7.75 DB
*MULTIPLICATION FACTOR: 19X
*POWER RATING: 2000CW. 4000 PEP
*WEIGHT: 14 lbs.
*LENGTH: 26 feet
*MATERIALS: 6063T-6 Aircraft Aluminum Tubing
*REQUIRES 1 COAXIAL CABLE FOR HOOK-UP

No problem using it on 26.965mHz to 27.405mHz at all. Whoever told you that didn't look up the specs as I posted here. You will have to tune it for length for the CB band. But the instructions should tell you how that is done. Or call Joe Gunn up yourself if it doesn't.

The old Son of a Gunn vertical i remember had the radials set at 90 degrees.

 

[Marconi]

the pattern is going in the right direction eddie, i don't like all that current in the mast/coax on either model, it looks like a worst case scenario,

maybe with some tweaking of element lengths and isolating the mast/feedline it could work like a sigma4,
avanti never said the hoop improved anything but bandwidth,
i don't think the wider angle they talk about in the patent included a hoop,

thanks.

You may be right. I usually watch the currents too, but for this project I ignored the current results. I think I tend to see such currents affecting the gain results more than anything else.

Here is an overlay of the FreeCell model of the JGSOG, my S4, and your idea for the SOG. Note how well the S4 does what FreeCell posted in the thread I referenced. It really compresses the pattern in all the important areas. With a peak gain at 4.51 dbi @ 8* degrees, the green line.

View attachment Overlay S4,FC,Bob's idea.pdf

 

[Mudfoot]

Funny

The manual says tunable from 26.000-29.500, but also states not intended for 11meter use. What's up with that?

 

[Marconi]

Bob, here is my S4 model at 36' feet with just the hoop removed. It seems to have a great effect with this model. NH at the end of the model name is for "no hoop." Check my earlier S4 model and see that the currents and the maximum angle is much better than it is without the hoop. That surprised me. I didn't make the radials longer either, so that too could have some unknow effect.

View attachment Sigma 4 052711 @ 36' NH.pdf

m42duster, it's my opinion that JGunn may have to work under FCC scrutiny, and does that for legal reasons.

If not, then what do you think might be going on?

 

[Mr.5150cbrn]

Thanks Jeff,...Its not a total loss...does anyone know of any Adjustments like makeing the elements shorter or something.. my antron still out talks it,,I got the swrs down to 1.6 I could give a Great testamonial For solarcon...THANKS AGAIN....LEE

well making the elements shorter will only get you further into the top end of the 10 meter band , but you might try lengthening the elements
if your swr is 1.6;1 whats your gripe ?
1,6 swr is perfectly fine as only flat lining will only give you bragging rights
btw what kind of coax are you feeding it with , hows it mounted , how high, ? more info , besides not reading directions .
you might try letting it "season" as things will improve on rx / tx
one other thing if you cant figure this antenna out ? what chances are you'll be able to operate a penetrator 500

 

[bob85]

how did you do this last model eddie, start from scratch or edit the hoop?
there is something not right with the monopole currents,
it has to be 3/4wave electrically to have significant antenna mode current if its not gamma fed,
did you extend the radials to compensate for losing the hoop?

 

[Robb]

The manual says tunable from 26.000-29.500, but also states not intended for 11meter use. What's up with that?

Ham politics?

 

[Marconi]

how did you do this last model eddie, start from scratch or edit the hoop?
there is something not right with the monopole currents,
it has to be 3/4wave electrically to have significant antenna mode current if its not gamma fed,
did you extend the radials to compensate for losing the hoop?

No Bob, I used the same model. I just deleted the wires for the hoop and left the radials. I didn't change anything else. I didn't even do a segment or geometry check, but this test checks out fine. The currents show to be very low in the radiator without the hoop. Most of the currents are in the mast and bottom 1/4 wave area.

For me, this may be a sure sign of the possible affects of excessive currents on the mast in antennas. This condition appears to push the maximum gain lobe up higher in all of my models. If I checked the tabular currents report I probably would see a decrease in currents in the radiator as a result. I think you would suspect that to be going on as well. In my mind a mast with excessive currents flowing...radiates more or less like a long wire.

If you want to see the tabular currents report, I'll run it, make some notes on it, and post it up. I looked at this report and it shows a phase shift in the radiator at segments 8,9,10, near the top. The radial currents in both models are in phase with the radiator, except for the tip of the "no hoop" model. This occurs at the phase shift noted above. That surprised me, and it is surely not good.

There is way too much going on in the S4 or this JG for me to understand. I can't be sure this model even represents a modest look at these antennas.

Here is a better view of the model, showing more of the antenna and the currents. I didn't look at this earlier, but the mast and the 1/4 wave at the bottom are doing all of the radiation.

View attachment Bob's questions currents.pdf

 

[Marconi]

Bob, here is a fixed model of the S4 without a hoop. I made the radials longer, and the model looked more like the S4 model. I have not check the affect of the change on angle, if any, but that could have happened messing with wires that are just hanging out in space and not in line with x,y, or z.

The second image shows a better view of the currents. I just turned the antenna a bit more to the broadside. I did not increase the magnitude of current for the image.

View attachment Bob's idea for longer radials..pdf

 

[Captain Kilowatt]

The manual says tunable from 26.000-29.500, but also states not intended for 11meter use. What's up with that?

Ham politics?

I suggest that you both familiarize yourselves with the regulations regarding antennas. Several years ago a law was passed that prevented omnidirectional CB antennas from being made of metal. There are only allowed to be made of a non-conductive material like fiberglass. It seems someone thought too many CB'ers were killing themselves by contacting power lines while erecting their antennas. The Jo Gunn antenna in this thread is made of aluminum therefore is not allowed to be erected for CB purposes. I know, stupid law but nevertheless that is the reason why it is stated as not for use on 11m. BTW lets not get into a CBer versus ham stupidy thread regarding antenna erection. The government passed the stupid law and had nothing to do with hams. Just thought I would drop that little note as this has been brought up several times before and almost always evolved into a "hams are smarter than CB'ers so they are still allowed metal antennas" thread. We do not want that to happen.


http://www.access.gpo.gov/nara/cfr/waisidx_04/16cfr1204_04.html