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[Articles Home]  [Add Article]  

The J Stand

from Dale Kubichek, N6JSX on August 14, 2012
View comments about this article!

The J Stand

By N6JSX /8

The 2m/440 copper-pipe J is truly a simple and most effective antenna that does not require any counterpoise radials/ground. When Im on the road as a Contract Engineer I take a J, 50w mobile and an Astron VS12M with me. Most extended stay motels/apartments will not allow mounting any antennas to their structure. Leaning a J against the wall compromises the low angle radiation pattern of the J. I solved this by making a solid but removable stand for the J allowing me to place it on the patio, balcony or in the corner as a hat stand.

The PVC stands (and hat rack antlers) are made from PVC, elbows, cross, 45- angles, end-caps, thread adaptor, PVC glue, and some brown spray paint.

The key to these stands is the use of copper-pipe CXM copper adapter soldered to both ends of the long J element that allows the use of threaded PVC fittings.

I placed a copper sleeve (only soldered to the lower section) in the middle of the long J element. The J breaks down into two 40 copper pipe pieces. Now I can easily unscrew the PVC parts from the J make and make all easy to pack and ship!

NOTE: the PVC gluing of the legs can be tricky to insure the legs are placed properly during glue drying to insure the J remains balanced and perpendicular to the floor. I hung a bubble level on the long J element to insure dead-center balance alignment. The great thing about PVC is if you mess up it was a cheap mistake to replace/repair!

Page 2 of 2
Copyright 2012, N6JSX Sidney, OH
All rights reserved only non-profits may copy or reprint.

Member Comments:
This article has expired. No more comments may be added.
 
The J Stand  
by K5END on August 14, 2012 Mail this to a friend!
Very clever idea. Thanks for sharing it.
 
The J Stand  
by K8AXW on August 14, 2012 Mail this to a friend!
Very nice. Although I no longer travel I do enjoy porch setting and a full sized antenna would be great to use with my HT.

With that being said, I am disappointed in the article overall for several reasons.

You claim 2M/440 but no dimensions are construction details are given for this dual band antenna. Although the 2M J-pole will radiate on 440, the effeciency is terrible. Did you modify the 2M dimensions to accomodate both bands?

What is the "coat rack" configuration on the top or is this the 440 part of the antenna?

Does the antenna tune differently being this close to the ground than a J-pole that is elevated.

I really like your idea and hope to replicate it but it sure would have made a much better construction article if you would have included more detail.

Al

 
RE: The J Stand  
by K2FOX on August 14, 2012 Mail this to a friend!
Great idea, thanks for the . I've got most of the parts already onhand. I'll be taking a little vacation to the beach in September, I think I'll give it a try. And I like the coat rack idea, you could sit this in the corner of a room and it would blend right in.

And as far as the article goes, I don't see a problem with it. Think of it as an idea article and not a construction project with detailed dimensions and pictures. Get out your calculator and figure it out for yourself, we are a HAMs, aren't we?

-Jay
 
The J Stand  
by N6JSX on August 14, 2012 Mail this to a friend!
AWX: please search eHAM articles for my "The SIMPLE 2m Copper 'J' Antenna" Sept 2001, article via my callsign search. FYI, I'm in the process of doing a rewrite of my succesful J article with leassons learned and new/improved methods/pics/data.

This article was just for the stand to support a J (or other) antennas.
 
The J Stand  
by N6JSX on August 14, 2012 Mail this to a friend!
AWX: please search eHAM articles for my "The SIMPLE 2m Copper 'J' Antenna" Sept 2001, article via my callsign search. FYI, I'm in the process of doing a rewrite of my succesful J article with leassons learned and new/improved methods/pics/data.

This article was just for the stand to support a J (or other) antennas.
 
RE: The J Stand  
by G8HQP on August 14, 2012 Mail this to a friend!
Does it use a balun or feeder radiation?
 
RE: The J Stand  
by K9MHZ on August 14, 2012 Mail this to a friend!
G8HQP.....I hope you're not looking to start something here. Everyone knows the shortcomings of a J pole, especially in feeding/coupling. But, they're just convenient to transport and work OK, but not great.

I hope a furball doesn't start over this one. I guess we're due for one, since it's been a while.


 
RE: The J Stand  
by K8AXW on August 14, 2012 Mail this to a friend!
JSX: Thank you for that info. I presently use a J-pole for my 2m base station. I also have a J-pole that is inclosed in a length of PVC pipe that I built some time ago for emergencies. It can be hung in a tree or whatever.

I'll research yor article and get started on this one. Thanks again.

Oh, as for doing the calculating myself... sure I can do that. But, why re-invent the wheel when JSX has the numbers? No only that but I was interested in the affect of being mounted close to the ground has on the numbers. It would be very difficult to calculate that!
 
RE: The J Stand  
by K2WH on August 15, 2012 Mail this to a friend!
A so-called J-Pole is a very poor performing antenna. Those considering to make one, should consider a much better performing antenna called a simple vertical. True a vertical requires radials, but they are only 19" long and can be fed directly with coax. Not tuning, no baluns no nothing.

The J-Pole in this article, mounted the way it is (at ground level), might only be better than the rubber duck on your HT since the duck will be at a elevated level.
 
RE: The J Stand  
by N6JSX on August 15, 2012 Mail this to a friend!
WH: it's nice to see another arm-chair guru has sounded off. I for one find the J the best flat-land vertical one can use/make, especially when no ground radials are required and having the lowest angle of radiation known.
I noticed in your 'opionion' you offered NO alternatives, just a negative. What value is that to all? Or is that the point 'hit-n-run' leaving nothing to be challenged so as to retain your self proclaimed guru status?
 
The J Stand  
by N1LWK on August 15, 2012 Mail this to a friend!
Nice idea. I built my first j-pole 20+ years ago and made several more since then. My first j-pole was a real learning experience. I soon learned that my soldering skills were very poor. With a little help I finally put together a great little antenna.

No, the j-pole does not perform as good as the Diamond that is now in my back yard. But at the time, I was an apartment dweller and the j-pole became very handy for me.

Good work. 73....N1LWK
 
The J Stand  
by KT4EP on August 15, 2012 Mail this to a friend!
This type copper J pole is a great little antenna for local repeater and simplex operations, easy to build and use, portable, and a good beginner's project. I have two of them from the early 1990's. Several of us got together at a friend's shop and whipped them out left and right. It's a good club project. Don't be dissuaded that its a poor performer and not worth your time to make and use. Of course, if you are a serious VHF/UHF ham wanting to make more distant contacts, then put something up high and in the clear. But this is a good little antenna for what it is.
 
The J Stand  
by KB5ZSM on August 15, 2012 Mail this to a friend!
One reason this country is failing is literacy. The title says The J Stand, not J pole antenna or How to build a J pole or how great a J pole is. Just a STAND!!! Whew!!!
 
RE: The J Stand  
by K2WH on August 15, 2012 Mail this to a friend!
WH: it's nice to see another arm-chair guru has sounded off. I for one find the J the best flat-land vertical one can use/make, especially when no ground radials are required and having the lowest angle of radiation known.
I noticed in your 'opionion' you offered NO alternatives, just a negative. What value is that to all? Or is that the point 'hit-n-run' leaving nothing to be challenged so as to retain your self proclaimed guru status?

Never said I was a guru, but I'll take the compliment. You proved my point however with your idiotic statement that it has the lowest angle of radiation known. Since it is mounted at ground level, having a low angle of radiation is a detriment and might get you to the next block.

K2WH
 
RE: The J Stand  
by K2WH on August 15, 2012 Mail this to a friend!
The J-pole antenna, also called the Zepp' antenna (short for Zeppelin), was first invented by the Germans for use in their lighter-than-air balloons. Trailed behind the airship, it consisted of a single element, one half wavelength long radiator with a quarter wave parallel feedline tuning stub. This was later modified into the J-pole configuration, which became popular with amateur radio operators because it is effective and relatively simple to build.

The J-pole antenna is an end-fed omnidirectional dipole antenna that is matched to the feedline by a quarter wave transmission line stub. Matching to the feed-line is achieved by sliding the connection of the feedline back and forth along the stub until a VSWR as close as possible to 1:1 is obtained. Because this is a half-wave antenna, it will exhibit gain over a quarter-wave ground-plane antenna. The J-pole is somewhat sensitive to surrounding metal objects, and should have at least a quarter wavelength of free space around it. The J-Pole is very sensitive to conductive support structures and will achieve best performance with no electrical bonding between antenna conductors and the mounting structure.

A well known variation of the J-pole is the Slim Jim antenna, which is related to the J-pole the way a folded dipole is related to a dipole. The Slim Jim is one of many ways to form a J-Pole. Invented by Fred Judd (G2BCX), the name was derived from its slim construction and the J type matching stub (J Integrated Matching).

Both antennas should ideally be fed with balanced line, however a coax feed line may be used if a balun is added. Commonly, a choke balun is used, or an air transformer, using about five turns of coax. Typical construction materials include copper pipe, ladder line, or twin-lead. Coax can be used to match the J-pole as somewhere between the closed circuit and open circuit of the stub an exact 50 ohm impedance match exists.

The J-pole design functions well when fed with a balanced feed (via balun, transformer or choke) and no electrical connection exists between its conductors and surrounding supports. A common approach extends the conductor below the bottom of the J-pole resulting in additional and undesirable RF currents flowing over every part of the mounting structure. This modifies the far field antenna pattern typically, but not always, raising the primary lobes above the horizon reducing antenna effectiveness for terrestrial service.

J-pole antennas with electrical connection to their supports often fare no better, and often much worse, than the simpler Monopole antenna.

 
RE: The J Stand  
by K9MHZ on August 15, 2012 Mail this to a friend!
Well, here we go again.

OK....the J Pole works, but not great. It's easy to make and easy to transport. In JSX's defense, he didn't go on and on about how super the antenna design is....his gist was mostly of portability and ease of building.

Personally, I've built them, as have probably most hams at one time. They're OK, but personally I'd never buy one from one of the ma 'n pa outfits who DO make outrageous claims about their performance.



 
RE: The J Stand  
by K0BG on August 16, 2012 Mail this to a friend!
The J-pole is a lousy antenna, compared to a common 1/4 wave vertical. All you have to do is model itjust don't forget to add the feed line into the equation.

Alan, KBG
www.k0bg.com
 
The J Stand  
by N7KFD on August 16, 2012 Mail this to a friend!

I love the way these always stay on topic.

N6JSX, great idea and thanks for sharing. I have a J-pole that I built several years ago in the garage collecting dust. Maybe it's time to get it out and start using it again, plus I always like a good project.

Thanks again.

Jim
 
RE: The J Stand  
by K8QV on August 16, 2012 Mail this to a friend!
It's not an antenna article. Still.
 
RE: The J Stand  
by K2WH on August 17, 2012 Mail this to a friend!
Many here would love for posted articles to remain as is; no matter if the subject is about something in which past analysis has proven the article details wrong or loaded with misinformation.

Well that ain't the way it is. You are posting on a ham radio site with many old timers, engineers and hobbyists who are experts in this type of work who have been there done that and will offer an opposing view.

While the "J" stand is about a stand to hold the antenna in a vertical position (nice job), it is undoubtedly an inferior antenna with very poor performance vs a simple vertical.

K2WH
 
RE: The J Stand  
by K9MHZ on August 17, 2012 Mail this to a friend!
Coincidentally, this month's QST has a submission that's almost identical, starting on page 41. The guy does show a 5 turns of coax, attempting to decouple the coax shield.

Breaks down and probably packs up nicely. But yes, unless you're climbing some terrain and need something that can become compact, small commercially available antennas are much better.

These antenna wars remind me of something in the flying world....namely the debate over canards. Claims by Burt Rutan (Voyager, SpaceShipOne, Global Flyer, etc) led people to believe that the configuration was both "stall proof" and "more efficient" than conventional configurations. One aero lecturer summed it up best..."if canards were even a fraction more efficient, Boeing and Airbus would have been all over them decades ago."

Probably similar to why the big boys don't manufacture J Poles.

 
The J Stand  
by N3AIU on August 17, 2012 Mail this to a friend!

If you want 2m and 70m, why not use a discone? It worked well on both of those bands, as well as 220MHz and 900 MHz. Also, the commercial ones break down very easily. I have two of them. One mounted in my attic to hit the local repeaters and another for portable use.

Yes, I know that this is a J stand article ...

73, Nick N3AIU
 
The J Stand  
by N3AIU on August 17, 2012 Mail this to a friend!

Plus, discones sit on the ground perfectly well by themselves.
 
The J Stand  
by K9ZW on August 19, 2012 Mail this to a friend!
Thank you for sharing!

Nice setup for those "road warriors" who get sent to work somewhere for a while.

Notice the J-Pole tech discussion. For all the various issues and options, the J-Pole works well enough - like they say "the best antenna is the one you actually have up & working!"

I've had success and a lot of fun with some very less than perfect antennas.

Great thing about our share hobby interest is the options that do work are huge! Best option is usually dependent on specific conditions, and there is always another tweak/option/method to try to get that bit more.

All best and 73

Steve
K9ZW

BLOG: http://k9zw.wordpress.com/
 
RE: The J Stand  
by KT4WO on August 20, 2012 Mail this to a friend!
RE:"The J-pole is a lousy antenna, compared to a common 1/4 wave vertical. All you have to do is model itjust don't forget to add the feed line into the equation.

Alan, KBG
www.k0bg.com "


I agree ---

Use the "stand" to mount a 1/4 wave G/P.
It will work better.

KT4WO
 
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