Base Working on a 1/2 wave J-Pole

[Marconi]

I think you missed something Steve.

Back at that time you were having discussions with Needle Bender and they were a bit heated at times. So, I figured my questioned just fell through the cracks...as is often the case in these forums.

You could not find a post, where I asked you again the 2nd time...if you could explain specifically what GHZ24 said in his heads-up to you about how to manage the Average Gain, because it was in a conversation with me entitled "Avanti A/P dimensions" June of 2017.

A PDF file is below.

At the time I read your post I copied it and emailed it to myself...so I would have a reference if the subject ever came up again. See that in my link in post #14 above.

I haven't consider this until Henry brought it up today. His words sounded remarkably similar to your words. I simply used the word just like you did. So, here I am defending myself.

If you want, ya'll can do a search on this forum for the word "trick" using no members name, and you'll find the word used 100's of times, and I would guess without an issue.

 

[Henry HPSD]

Guys...

Its freezing here, and with the wind blowing brr...cold outside...

Anyway.. "trick"
Its just a word...and yes, that word leaves(at least to me) a impression:

Pay attention...what is going on.... Thats cause we all know
Theory is often not understood, which makes people sceptical.....especially if they have been fooled in the past.. We all are 'caution" about "tricks" in the antenna world.
Its "tricky" to use that word (LoL)
But it can also be a good thing as well...
Heck im using a lot of "tricks" to deal with many situations....then to me..its just smart to do !

So...i havnt read it (yet)...and im one of the sceptical people (by nature hihi)..So im wondering what is going on...And i wasn't aware DB did a lot of "checking" no I am..im already feeling happy, DB is a smart guy, i have faith its oke to "use" that trick..

No more No less.

Im into :
Hm...I might have found a way...or call it a trick..at least it seems a solution....
......for certain situations that otherwise provides issues........
Here is it: .........X.+Y = Z....
What do u guys think ?

Now im thinking you already had that conversation,
(The: Hey guys ! I have an idea, what do you think ? one)
Ill do some catching up.

Enjoy the Sunday !

Kind regards,
H->

 

[Marconi]

A question was asked Marconi, how would I attach a mast to this J-Pole.

1. Here is my Free Space version of the model for the Real Earth J-Pole that I posted in the beginning of this thread. This model shows the Average Gain and is the bases for the real Earth model to follow.

Next I set this model to the Real World settings...which turned all the losses on and I added an isolated mast. This was done to insure a good Average Gain and the soundness of the real Earth model. This is the model that I originally posted in this thread.

2. Then I took this real Earth model and connected the mast directly to the antenna (no isolation). Here we see a very bad pattern, match, and other performance results when the mast is not isolated from this J-Pole antenna. IMO, this indicates we have CMC's on the mast and/or the feed line which was not model in this project. Notice in this antenna's image there is more current on the mast than there is on the antenna...and that is no-way-no!

Then I added a modeling remedy for the terrible ill-effects of adding the mast directly to this J-Pole, and this model has no isolation (ISO) and the performance results look normal again and no CMC's are to be noted on the mast.

Conclusions:
However, this is not all that is necessary to regain a good pattern and high performance results. This is because we use a feed line in our real setups. This model only simulates what can be done if a good working CMC choking remedy is installed on the feed line or mast, as in this case...where we then see no CMC's flowing on the direct connected mast. If the setup still manifests CMC's then the mast probably needs to also be isolated.

BTW, I would use an Axe handle, or a nice dowel of Redwood, or some good synthetic material for the isolator.

 

[Marconi]

Here is another method of mitigating CMC and mounting a J-Pole directly to the mast, thanks to the courtesy of hamradio.me
http://www.hamradio.me/antennas/j-antenna-variations-thereof.html

Bob, I also faced the J-Pole toward the Y coordinate, so we can see the skewing.

 

[Shadetree Mechanic]

Here is another method of mitigating CMC and mounting a J-Pole directly to the mast, thanks to the courtesy of hamradio.me
http://www.hamradio.me/antennas/j-antenna-variations-thereof.html

Bob, I also faced the J-Pole toward the Y coordinate, so we can see the skewing.

A mast decoupling stub? Wait, what? Wow. Now I have some reading to do!

 

[Marconi]

A mast decoupling stub? Wait, what? Wow. Now I have some reading to do!

When I saw the antenna on www.hamradio.me I did the modification to the J-pole I posted earlier.

I just copied the wires for the matching section, less the feed point, and set the new stub down the mast the length of the long wire for the feeder stub. I connected the wire ends and the model worked the first time I scanned it.

I did it to see if it worked, and it decoupled the mast below as well as the choke I used earlier. I did not read all the comments on the website for this antenna, but I wonder what they have in mind if the feed line was included in the model.

Some of their J models use a feed point exiting at a 90* degree angle...so maybe that is the solution. I haven't played with that idea yet.

 

[Marconi]

s

I did it to see if it worked, and it decoupled the mast below as well as the choke I used earlier. I did not read all the comments on the website for this antenna, but I wonder what they have in mind if the feed line was included in the model.

Some of their J models use a feed point exiting at a 90* degree angle...so maybe that is the solution. I haven't played with that idea yet.

As noted above I asked what will happen when the feed line is added to this decoupling stub J-Pole antenna. Well, I had no idea but I did ask the question.

Below is the the model of the J Antenna with the feed line added and the image is shown with a red line on the 4th page in this PDF file, Here you will see the feed line terminate at the source (O) the feed point.

I recently visited the www.Hamradio.me Website again and it has been updated. I wanted to follow up on what happens when the feed line is added to this antenna. John Huggins claims the J antenna is fully conductive and the decoupling stub takes care of the typical CMC for J-Pole antennas including the feed line.

Here is a link to the patent: https://patentimages.storage.googleapis.com/0f/16/e0/c9bbc9feec78af/US20170201002A1.pdf

 

[Marconi]

Here is the J Antenna with feed line losses added to the model showing the effects on match and gain.