JPole - ish?

[wqzw301]

Has anyone seen this type of J Pole. I believe from past articles, I've read; it is an end fed dipole?
This one is from b-square engineering. It is uhf version, made out of stainless steel.
Has anyone done or seen any computer modeling of this type of antenna. Is it a true half wave antenna?
Also, does stainless steel effect high frequencies like uhf? It has a lower velocity factor but is it like nickel plating at high frequencies?
Please and thanks for any input on this topic.
d

 

[nd5y]

A dipole has two halves. You can't end feed a dipole.
It looks like a bottom fed J-pole. Arrow makes similar models with the same basic design.

I modeled that type of antenna with MMANA-GAL. If the 3/4 wave and 1/4 wave elements are at the right spacing the 50 ohm point is at the bottom. The theoretical radiation pattern is about the same as a normal elevated feed J-pole or any other 1/2 wave vertical. There is nothing to properly decouple the feedline so in real life feedline radiation will be a problem and you will have an unpredictable radiation pattern depending on the feedline length, position, height and nearby conductive objects.

If you want a UHF vertical there are a lot better ones. If you want something small then a ground plane would be better.

 

[wqzw301]

A dipole has two halves. You can't end feed a dipole.
It looks like a bottom fed J-pole. Arrow makes similar models with the same basic design.

I modeled that type of antenna with MMANA-GAL. If the 3/4 wave and 1/4 wave elements are at the right spacing the 50 ohm point is at the bottom. The theoretical radiation pattern is about the same as a normal elevated feed J-pole or any other 1/2 wave vertical. There is nothing to properly decouple the feedline so in real life feedline radiation will be a problem and you will have an unpredictable radiation pattern depending on the feedline length, position, height and nearby conductive objects.

If you want a UHF vertical there are a lot better ones. If you want something small then a ground plane would be better.

Thanks, not looking to use one, just interested. Decoupling would probably need fiberglass mast and some ferrites on the coax at feed point....
Thanks for the clarification. Very interesting.
D