J Pole Antenna

[WSHE531]

What’s everyone think about the j pole antenna?

[SteveShannon]

25 minutes ago, WSHE531 said:

What’s everyone think about the j pole antenna?

You’ll get quite a range of different opinions.

[WRYZ926]

Steve is correct. You will get opinions ranging from hey are junk and no better than a dummy load to they are great antennas.

I have a 2m and 70cm Fara-J antennas to test out once the swamp dries up a little. They are clothe j pole antennas made with strips of faraday clothe. You can make your own or buy them from https://vfcomms.com . They make a 6m, 2m, 70cm, GMRS and Meshtastic version of their Fara-j antennas.

I went to check the yard today and what a muddy mess. We went from snow and single digit temps all last week to 60 degrees yesterday and today.

 

[Socalgmrs]

Yuck.  Why bother you can get amazing antennas that work waaay better, look better and are cheaper.  They are junk. 

[SteveShannon]

Based on what I’ve read, the ones made,of copper tubing are about equivalent to a dipole in performance, not high gain, but decent omnidirectional performance. I intend to build one this spring sometime. It’ll be single band, possibly 6 meters.  That’s the only vhf band I don’t have an antenna for now.

[WRYZ926]

Well that didn't take long. I knew Negative Nancy would put his worthless half  a pence in. The negative vibes need to go.

Plenty of people use J pole antennas with great results. One of my friends has made several J poles for GMRS for other club members and they all work. He has also made a 6m j pole out of copper and a giant 11m/CB j pole out of aluminum tubing. It works well too.

I have a 2m j pole made from 3/8" aluminum rod that works well and sometimes use it portable. I also made the faraday clothe j poles for portable work.

[WRHS218]

1 hour ago, Socalgmrs said:

They are junk.

Yep. I have two, one for 2m and one for GMRS. They both work very well for my needs.

[Reloader762]

I've had the Ed Fong GMRS J Pole for about a year now and have been very happy with it. I'm able to hit repeaters in the area, some as far as 45 miles away, or use it for local simplex communication.  Of course, antenna height, line of sight from you to the repeater or station you're trying to reach will make all the difference. There are probably better options as far as base antennas for GMRS out there, but I choose mine for easy of mounting.

[WSEZ864]

I don't think a J-Pole is a "bad" antenna, but there are others that perform better. I think the performance niche for a J-pole is like Ed Fong's portable/roll-up, where it provides good performance with great portability.

I have a rigid J-Pole made of copper pipe and tested it side by side with a 1/4 wave ground plane and the ground plane performed noticeably better.

[Lscott]

9 hours ago, WSHE531 said:

What’s everyone think about the j pole antenna?

I think before that question it's important to understand what it is, and isn't. There is a good write-up at this link.

https://en.wikipedia.org/wiki/J-pole_antenna

Most of the issues with the antenna stems from it's radiation pattern. Depending on construction and installation the antenna may present some noticeable asymmetric gain characteristics.

One other important point is the antenna requires some kind of "decoupling" network for the connecting coax cable. That's typically done using some snap on ferrite cores very close to the feed point, or a coiled up section of the coax cable. If this isn't done then all sorts of weird highly asymmetric gain characteristics may occur along with high SWR readings, and even RF getting back into the radio causing distorted audio.

 

[tweiss3]

Like others have said, they are inexpensive, and can be built at home. If you want to experiment, go for it. The unfortunate thing is they are not that inexpensive when only a few bucks more you can get a real antenna that doesn't have a big null (see link above).

[SteveShannon]

20 hours ago, tweiss3 said:

Like others have said, they are inexpensive, and can be built at home. If you want to experiment, go for it. The unfortunate thing is they are not that inexpensive when only a few bucks more you can get a real antenna that doesn't have a big null (see link above).

Are you talking about the vertical null?

[warthog74]

I went with a copper j-pole for 3 reasons. Weighs 1 pound, it has next to no wind resistance, and cost. With my cobbled together setup consisting of thin 1 1/4” aluminum electrical conduit with some wood slats to help anchor it from swaying, it made the most sense. There will always be something better. There will always be something worse. For me it works well and does what i ask of it. No complaints. I also have another j-pole that i have 50 feet up for my small solar powered GMRS repeater. I set it up for our (semi rural) neighborhood to use, but it actually covers about 10 miles. Again, no complaints. People can crap on them all they want, but a copper j-pole wont snap in half or splinter like fiberglass does. Oh, and i clear coated mine, so don’t yell at me about oxidation.

 

J-pole base station antenna at about 30 feet. (Don’t mind my cat. He loves it up there).  

J-pole repeater antenna at 50 feet on 30’ flagpole + 20’ aluminum electrical conduit.

[WRUE951]

I have two homemade versions of the J-Pole, the copper, the twin lead J-Pole..  Both work as a pretty decent GMRS antenna, especially considering the cheap cost building them..   I use the copper j-pole for my portable camping antenna because it's light, compact, easy to store, easy to set up  and it offers pretty decent performance.. I can talk 75-80 miles with no problems with the copper J-Pole, it's very omnidirectional. It works ok in flat valleys but likes to be elevated to get best coverage (i.e. high elevations like up in Mammoth area)...  Mine is built on the KB9VBR's design with a few medications which i posted on this forum..  The twin lead is also a good choice but i've had better luck with the copper version. The Twin Lead is a little more complex to build. . Neither antenna will out perform a good medium gain base antenna but will come close..  Bottom line, for the cost to build one, (about $20 bucks for a copper J-pole) you can't go wrong...  

[WRYZ926]

The club member that has made a bunch of j pole antennas actually uses some old solid center conductor 75 ohm coax cable for the GMRS j pole antennas. So far they have held up through all types of weather conditions. The center conductor on the 75 ohm coax is fairly large so it holds up well.

[Socalgmrs]

Any one that thinks I poles or Ed fongs are hood antennas have never used anything else.  They don’t work and are totally junk.   Just get a real antenna. 

[Lscott]

55 minutes ago, Socalgmrs said:

They don’t work and are totally junk.   Just get a real antenna. 

They are real antennas, and they do work.

[SteveShannon]

11 minutes ago, Lscott said:

They are real antennas, and they do work.

Exactly.  They have almost exactly the same low gain and RF pattern as a dipole with a null in the direction of the axis of the element. They’re vertically polarized. And they’re relatively easy and inexpensive to build if a person has an antenna analyzer, tubing cutter, tape measure, and can follow simple instructions.

Saying get a real antenna is simply a way to put down others.  I don’t believe @tweiss3 intended it that way because it’s out of character for him (I was surprised to see that in his post), but it’s true to @Socalgmrs character.

[Lscott]

I did some quick screen captures of a Ham 70cm J-Pole simulation I had done some time back to show what people can expect. The radiation pattern of most interest is the azimuth one, perpendicular to the vertical element. As seen in the attached images there is some asymmetrical gain variation. The vertical, elevation, pattern is more complex and only of interest if the other station is at high angles , above or below, the perpendicular point.

Edited 1 hour ago by Lscott
Added the antenna model view with the wire connection table.

[WRUE951]

1 hour ago, Socalgmrs said:

Any one that thinks I poles or Ed fongs are hood antennas have never used anything else.  They don’t work and are totally junk.   Just get a real antenna. 

Actually your are wrong..  Both are good antennas for their purpose..  Both are 1/2 wave antennas and require no ground plane.  If you have a situation like an RV, Boat an Apartment building or application where you need to keep your antenna 'under cover'  I guarantee you cant beat the J-Pole.  I use a Copper J-Pole for my RV while camping and won't use anything else for that propose..   Yes,,,like anything, you can build a crappy J-Pole..   Getting them right is tricky but do it right, you have a decent good performing antenna  

[Lscott]

4 minutes ago, WRUE951 said:

Getting them right is tricky but do it right, you have a decent good performing antenna  

That's really the whole issue most of the time.

[WRHS218]

53 minutes ago, Lscott said:

59 minutes ago, WRUE951 said:

Getting them right is tricky but do it right, you have a decent good performing (Insert life situation here) 

That's really the whole issue most of the time.

That's really LIFE most of the time.

[tweiss3]

1 hour ago, SteveShannon said:

Saying get a real antenna is simply a way to put down others.  I don’t believe @tweiss3 intended it that way because it’s out of character for him (I was surprised to see that in his post), but it’s true to @Socalgmrs character.

No, wasn't meant in that way. With the cost of copper, or the PVC required for an EdFong, the cost difference is indistinguishable between a jpole and a commercially sold antenna. I've put up too many "good enough" antennas only to have more problems replacing them than it was worth just a year or so later.

I can't find where it was documented, but there was a a study/model that showed a horizontal null with the jpole. I was able to find this null while rotating an edfong antenna. It's now used in the attic for a single frequency monitor where the null doesn't matter. 

I encourage everyone to build antennas of all kinds, and everyone should have one (or more) sitting around to toss up in a temporary setup. The jpole is almost perfect for that.