W6FIF's Silent Shield J-pole Antenna (

Ron, W6FIF, constructed a J-pole. He sent me his J-pole to look at and test. It has a nice designed and it is nicely portable. Watch to learn more about his J-pole and it's design.
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[@DrChazKL0T]

I loved the J-Pole analysis. Thank you.

[@Mike-H_UK]

Lovely antenna. If he'd left it anywhere near my granny, she would have polished it for him!!

[@d3w4yn3]

This is a cool antenna!!! I like it!!!

[@MarcusPocus]

i absolutely love where the feed point is, more practical.. no need of few turns of coax for to kill the capacitance?!? ..thank for the review.. question, i have a portable VHF/UHF FM 8 watts, have you a suggestion for a swr/power-meter able to have a good precision at this level?!? (most have 100-125w of range and are inaccurate at the bottom of the scale).. i dream of to build a brass J-Pole (elegance by the color and not oxydable).. happy of your review today!!

[@subramanianr7206]

Dave, it is my bad to comment again. There is nothing unique in the design (except for you); it is the regular J pole antenna. The only point I would like to congratulate him is that he is dare to feed the coax centre to the shorter side of the J pole. Yes, in almost all of the designs on the texts and elsewhere people will prefer to feed the centre conductor to the longer arm, thinking that it is the radiator side of the J pole that should be connected to the centre conductor of the coaxial cable. Of course the half lambda section is the end fed radiator, no doubt. But the quarter lambda transmission line section is there to have a match between the high impedance (around say 2-3 kilo ohm) of the end of the half lambda radiator and the 50 ohm coaxial cable. So, the coax centre can be fed to any of the two arms of the stub. After all RF is AC and it does not discriminate between the two conductors of the feeder. The problem lies in your mind that you think the centre conductor only carries the current and no current flows on the outer conductor or you think that it is at ground potential. The inner surface of the outer conductor carries equal magnitude of current (but of opposite polarity) as the outer surface of the inner conductor. The outer surface of the outer conductor is forced to the DC ground potential at the transmitter deliberately by us. That is all. The outer surface of the outer conductor should not carry any current (if it does, it is called the CMC (common mode current, which is undesirable) and it has to be choked. Again you are still confused about what a balanced feed is and what is not. Here, it is still an unbalanced feed only; not a balanced feed at all. And you should explain what the title "silent......" means!! You claim that it is unique that the feed is a balanced type. That is really awesome, Dave. I don't have to talk about the mechanical ruggedness of this "plumber's delight copper cactus" antenna. More comments will be pouring in on that, I know. And you were right about the fact that the j pole is nothing but the popular Zeppelin antenna and it becomes the double Zeppelin antenna if both the free ends of the 1/4 lambda transmission line stub are terminated into a half lambda long radiator. But it was hydrogen the Germans used in the ship that got burnt up resulting in the infamous accident. Germans knew about the flamable nature of hydrogen. But they could not get access to large quantities of helium to fill the chambers in the Zeppelin air ships. It was the US that was capable of producing large quantities of helium on the planet then. But then the war was nearby and the US would not sell any helium to Germany. Yes, helium being the second element on the periodic table is inert and would not have caught fire in the first place. It was unfortunate that the Zeppelin was filled with hydrogen, a highly reactive and self combustible gas. De VU2RZA

[@montybates5176]

He did mention, when he was outside, that it wasn't unique.

[@subramanianr7206]

​​@@montybates5176 Dave is testing outside of his house for 1 minute and comes back to his seat. Then at 5.53 he says that many people have tried the kind of feeding the J pole. At 9.22-9.23 he again says it is different and unique enough to get published in the QST magazine (as the designer had been thinking of) Hope you want to watch the video again De VU2RZA

[@ricksshop]

Curious if that feed point helps reduce common mode current on the feed line. Most J antennas I build will show SWR changes as you grab the coax and move it around.

[@wheelersecuritygroup]

Is there a reference (email or website) to lengths and diameters for each section of this J-Pole? I would like to build that with the modifications you suggested with the threaded areas. I don’t have any measuring devices to check the SWR & Impedance. Where could I get that measuring device to check that too. Also the black round section…is that foam?

[@johnbauman4005]

Every time I see one of these copper J-Poles I wonder how well a slide trombone would transmit 🤣🤣🤣. Forgive my ignorance but what is the "Silent Shield" mentioned in the title but not expressly named in the video? Thanks! John - KK7JBZ

[@subramanianr7206]

Silent shield is Dave's invented terminology...hi..hi.. De VU2RZA

[@davecasler]

Actually, it's the terminology from the inventor.

[@subramanianr7206]

@@davecasler so, he has invented the terminology and nothing new about the antenna. The job of explaining the meaning is shifted from your shoulders to his. That is very nice of you 👍😀 De VU2RZA

[@davecasler]

@@subramanianr7206 Whatever. He put the antenna together. He branded it. Lots of things have brand names. I will be doing more testing as well as a comparison to a "standard" J-pole in the future.

[@subramanianr7206]

@@davecasler Yes, please do make a review video on the antenna and it will be much appreciated by everyone. This time you may want to show the connection points (that is unique for sure as I have commented earlier) of the coaxial cable onto the antenna; in the present video you have been rushing through or you don't want to have a focused study on the unique nature. Probably it is he who claims it is a balanced feed assuming (of course erroneously) that he has quenched the shield braid or something like that. Hence he might have coined the term "silent shield" I suppose. Anyways I am waiting to see a follow up video with great expectations, albeit the fact that you won't find any difference in the performance. Thanks Dave 👍 De VU2RZA

[@AC3HT]

Thanks!

[@davecasler]

Welcome!

[@rickeaston3228]

I would use a telescoping antenna rod instead of copper pipe..

[@montybates5176]

Can you bolt this directly to a metal mast that is going to sit on the ground? Thanks Dave. kf0gpx

[@InflatedDolphin]

Why re-invent the wheel? There are literally THOUSAND'S of J-Poles in the air now with the same traditional feedpoint design, I even have one I made myself, I get better SWR readings than this one showed across 2m and it works equally well on 70cm, again with better SWR figures than shown. I know people like to experiment, but if your changing something that works perfectly already, you had better be sure your design is an improvement, not just an unneeded complexity. I think Ed Fong got the design right, his design has become the "standard".

[@ericm0612]

Apparently you missed the part where he talks about balanced and unbalanced feed point.

[@N2ELS.]

That's what ham radio is all about, to build and experiment.😊

[@glenmartin2437]

Thank you. N0QFT