Print Instructions for this J-Pole
Copper Dual-Band Super J-Pole Antenna Project
Your going to like this super J-pole project, This home
made j-pole is easy to build and sturdy, While looking for an
jpole antenna project to build I remembered seeing a Marine
antenna called the Super J-Pole in the 1988 ARRL Antenna Handbook,
which claimed a 6 db gain over a quarter wave ground plane.
I didn’t have a machine shop at my disposal to fabricate the
parts shown in the Marine antenna article so I set about redesigning
the antenna using materials that were easy to find and work
with. I have had very good results working with copper J-Poles,
so I built my refined version of the classic J-Pole. I then
added a short insulated section, the extra half wave of vertical
length, and the needed half-wave matching stub.
Here is a schematic drawing of the home brew J-pole (
Click Here ) Word
All the materials except the S0239 fitting can
be found at any good hardware store, and the whole antenna can
be made in less than an hour.
In my design I use 1/2" copper schedule M
tubing and 1/4" soft copper tubing. I had experimented
with using Teflon insulator, but have since changed my design
to use a 9" length of hardwood dowel with three coats of
lacquer as the insulator, for more strength.
Clean all the tubing, and then from the 1/2"
tubing cut one piece each of the following lengths: 57-1/2";
38"; 19"; 2", and a piece about 3" long
for a stub to mount the antenna. In addition to the tubing,
buy a 1/2" elbow, a 1/2" Tee, two 1/2" end caps
a 1/2" threaded fitting, and a cast iron floor flange for
mounting. Get a piece of 3/16" or 1/4" soft copper
tubing 42" long. Find the center of the 1/4" tubing
and bend it around a 1"-to-1-1/4" diameter water pipe
Put the Heat to it
Now fire up the torch and start the assembly process
from the bottom. See Figure 1. Use flux on all joints, solder
the 1/2" threaded fitting to the mounting stub, and solder
the 1/2" Tee fitting. Then proceed with the 57-1/2"
section, 2" cross piece, and 19" section. Pay close
attention to getting the 19" piece parallel to the 57-1/2"
piece. After these have cooled, drill through both the 57-1/2"
section of the 1/2" tubing and the hardwood dowel about
1/4" from the top end of the 1/2" tubing, and the
bottom of the 38" section of the tubing. (See Photo A.)
Then insert the 1/4" tubing to the 1/2" tubing and
sweat solder the end caps. After these have cooled, clean the
entire antenna, bend the half wave matching section to a half
circle of about 4" radius around the antenna to help the
balance and match.
Simplify the Feed Point of the J-pole
The feed point also needed to be made simpler, so I elongated
one of the mounting holes of a panel mount SO-239 fitting and
inserted a stainless steel adjustable band clamp. This goes
on the 57 1/2" long section of 1/2" tubing. A short
2-3/4" length of # 14 copper stranded wire is soldered
to the center terminal to go over to the 19" section. I
used another stainless clamp to attach this. (See Photo B.)
While experimenting to find the proper feed point, I found that
the distance above the crossbar should be about 3".
1 10-foot section of schedule M 1/2"
1 1/2" copper elbow
1/2" copper Tee fitting
2 1/2" copper end caps
1/2" copper threaded fitting (for
1 1/2" cast floor flange (for mounting)
1 Piece of 3/16" or 1/4" soft copper
tubing 42" long
1 Piece of 1/2" hardwood dowel of Fiberglas
1 SO-239 panel mount coaxial fitting
1 Piece of # 14 stranded copper wire
2 3/8" by 7/8" stainless band clamps
Solder and flux
A weight to keep parts aligned while soldering
Steel wool or a Scotch Brite pad (for cleaning
Spray can of clear exterior lacquer (to finish-coat
1. You may use a Fiberglas rod as an insulator,
but you will have to be very careful with the torch or you may
weaken or burn the rod, or make it brittle.
2. When cutting the 1/2" copper tubing, cut
the 57-1/2" piece from one end of the 10" length,
and the 38" piece from the other end. By doing this you
will have factory-cut edges for inserting the 1/2" dowel.
3. Be sure to keep the flame of the torch away
from the insulator to avoid burning it.
4. Use paste flux on all joints when fitting the
pieces together. Use enough flux, since you will be cleaning
the entire antenna with solvent after assembly.
5. Use a weight to hold the 19", 57-1/2",
and 2" pieces, and the Tee and the elbow, flat when they
are sweat soldered together.
6. Use a ruler or caliper to check the spacing
between the 19" and 57-1/2" pieces, to keep them parallel
to each other.
7. When drilling the SO-239 fitting, use the drill
press. Be careful not to drill into the threads of the fitting.
After the holes are drilled, file the opening flat for a better
band clamp fit.
8. After the best match has been found, you may
want to solder the SO-239 and the stranded wire end to the 1/2"
9. When the antenna has been cleaned and matched,
spray the entire antenna with a coat or two of clear lacquer
to keep it looking nice.
10. After everything else has been done, apply
silicon or a butyl rubber compound to the insulating section,
then cover the joint with electrician's tape for a weather tight
11. A 1/2" pipe coupling and a length of
pipe may be used in place of floor flange for mounting in a
First Name: Allen
Call Sign: n0sck
Comments: I built the Copper Cactus Dual-Band Super J-Pole in 1992, twice. The first used the dowel, the second I used a PVC 1/2 inch female coupler and two threaded copper male adapters. I shortened the upper and lower elements by the amount the adapters added. I also drilled and tapped one of the flats of each adapter and used 1/4 inch compression to 1/8th inch male pipe adapters for the matching stub, again reducing the length by the appropriate amount. I also fashioned a mount for the SO-239 by splitting a 2 inch lenght of 1/2 inch copper lengthwise and flattening out 1 half while leaving the other half alone. During tuning I simply clamped this to the pole, after I found the perfect spot I soldered it in place. ( See Picture )
This antenna has been up and in continuous use since 1992, It has never needed retuned (I use a MFJ 269 analyzer to check periodically. The winds in Kansas do blow and this is the only antenna that I have that has not needed repaired!
Suggestion by KB9TIO
An Improved(?) feed arrangement is to use copper couplings,
same size as the tubing. Split the coupling lengthwise, bend out
@ 1/4" and notch for the so-239 inner ring. attach with sheet
metal screws an/or solder so-239 to coupling. repeat with 2nd coupling
and solder other end of #14 wire to flat on coupling. this provides
a strong joint and very easy tuning by sliding the couplings up
or down the tubing as needed. this tip was given to me by Tom-KB9OZZ
Thanks, Matt KB9TIO
Suggestion by KD7GQC
I have also seen variations on the J Pole which omit the insulator
section. In the first, the center conductor is soldered directly
to the driver element, and the entire antenna is thus at DC ground.
The second variation is also an all-copper design, but you capacitively
couple the RF to the element, by wrapping several turns of insulated
wire from the center conductor around the driver section of the
J pole. I can't vouch for the second approach, but the first seems
to work great, for installations where a DC short to earth is not
a problem. It seems to me that eliminating the insulator section
makes for a simpler, and potentially stronger, design. Kudos on
a great antenna! 73s, Brian KD7GQC
I made one of your "J-Pole" antenna's with some mods. I cut 2 pieces of 1/2 tubing about 11/4" long and split them. I cut a 1/4' tab in the center of each, mounted my SO-239 to one and drilled a hole in the other for soldering the wire in. I used #10 solid copper wire for the center of the SO-239 to the short length of the "J". I used two 7/8" stainless steel hose clamps to hold each piece in place. I also used a full 3 foot length of 1/2" dowel rod to join the two longest pieces together. I drilled three holes thru the copper and dowel on each long piece of copper and used 7/8" 6-32 screws and nuts for each. This seems to add a great deal of support for the two.
KC5RFL has an antenna analyzer and he checked my SWR's. Came out 1.1:1 at 146.610mhz. Great.
|Call Sign wb5hds
Country: United States
Comments: I've used 10ft sticks of 1/2" galvanized 'emt' conduit to build my j-poles. i drill a 1/4" hole where the "j" goes on and use a piece of 1/4" copper and solder it in place, then attach the feed line. less than $6 invested using new parts. if you want a "super j", then use a piece of 3/4" pvc as an insulator and add your stub and pole, still very cheap. can't tell ANY difference in preformance. we hams have fun don't we....Dave
One last suggestion: put a piece of steel about 1/2 or 3/8 of about a foot and a half up
the center of it ( from the base ) this will strength the bottom portion
of the pole.. put a small curve in it so it touches the inner wall
of the pipe.. my parents use this j-pole and live in a windy area..
and this fixed that problem.
In order for these instructions to work
great.. Please send me feedback on if you had problems and what can
be done to help the next ham.. I don't get much feedback on the copper
cactus J-pole, Guess that's good in a way, but would love to either
here Praise or Suggestions
- Is there a specified distance between the top and bottom sections
(where the 1/4" soft copper attaches.
- ( Answer
is No ) About a 1/2 inch
- How do you attach the soft copper to the two sections?
- Drill 1/4 inch holes through pipe and wood and insert 1/4 soft copper
through and solder ends.
- I was wondering how you mounted the
S0239 onto the 53" pole. I was thinking of drilling a hole
and get the wire out from the other side to hold it better but then
when I read your description closely I saw that you mention that
you used the band clamp.
Answer ---Hard to describe but take your drill and drill a few holes
between 2 of the 4 holes on the so232 then try to remove the
rest of the material between these two holes, enough to get
the band clamp through then attatch to 53 inch pipe and take the
3 inch or so 14 gage wire, solder to center of the so232 and
attach to other side with 2nd band clamp)
check out new site that I'm building for ham Club..
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