Improving the Super-JAugust 5, 2012 by John Huggins

Super-J – As good as it gets?

The collinear J-Pole, often known as the Super-J, does improve the behavior over a regular J-Pole.

As many attest, there is an advantage when vertically combining 1/2 radiating sections to have a bit of separation between the half-wave end points.

The Super-J has very little separation between the two half-wave radiators.

Some web sites suggest the Super-J has a full 3 dB gain over the plain J-Pole which is a pretentious claim obvious to anyone with a copy of the ARRL Antenna Book and other references[1]. Indeed, the Super-J will never approach the gain advantage of a properly separated two element collinear antenna, but we can get closer to this goal.

Below you will read about how to get 0.8 dB more gain out of the trusty Super-J by replacing the traditional phasing stub with a long coil.

The Collinear J-Pole Phasing Stub

The all important phasing stub ensures the two main radiators of the Super-J are in phase. Without the stub you have a version of the erroneous 5/4 Wave J-Pole with its almost perfect cancellation of energy towards the horizon. To make the Super-J work, the conducting portion of the antenna (above the J-Feed) is made 3/2 waves long where the middle 1/2 wave is shaped to reduce it’s far-field net radiation. This leaves the two remaining radiators in-phase and contributing towards horizon coverage.

Focusing on the phase stub, we have the following possibilities in Figure 1…[Various Phase Stubs for Collinear J-Pole]
Figure 1 – Phase Stubs for Collinear J-Pole

Figure 1A – Franklin Array Stub [5] – Simple 1/4 wave stub
My original version of Hiking 2m J-Pole uses a simple bent pipe phasing stub 1/2 wave in total length or about 1/4 wave “stub” length. Normal operation places equal and opposite currents on the top and bottom pieces reducing the effective radiation of the stub assembly. Simulation and practice confirm this system works quite well.

Figure 1B – Simple stub bent into circle (known as ‘Curved Stub’ from now on)
Many builders take the stub above and bend it into a tight circle around the waistline of the antenna. This reduces the stub’s protrusion markedly and yields the same performance in a visually more appealing assembly.

Not Shown – 1/2 wave of wire bent into 1 turn coil
We can take the above stub and simply wrap it once around the waistline of the antenna to provide the same phasing benefit. The “single turn inductor” provides some cancelling of this middle 1/2 radiation, but not as well as the above techniques as will be seen below.

Figure 1C – Increasing the gain with more separation
As mentioned above the best vertical collinear antennas are realized with some separation between the two 1/2 wave radiators[1]. This is the only way to approach the “perfect world” 3 dB gain of a collinear over a simple half-wave. One way to do this is to take the single 1 turn coil and stretch it to the proper separation distance.

Figure 1D – Using a multi-turn coil for the phasing component
The above 1 turn coil can reduce its diameter by increasing the number of turns. The resulting assembly is very sleek.

Figure 2 shows the above stubs as they appear in the entire antenna assembly…[Full view of various Collinear J-Poles]
Figure 2 – Various collinear J-Poles.

Current magnitudes are shown to reveal what proper antenna phasing looks like.

Radio Telescope

As any Ham operator will tell you, we gather 'stuff'. We also have an awful curiosity about all kinds of things. My curiosity of the heavens has been further heightened by the possibility of harnessing two 10 parabolic dishes together to search the skies. Dishes have been acquired. Mounts have not been made yet. It looks like it might be a good welding project for me when I get bored. ;-)

Traveling Antennas

- more later on these.



Design your Own Super J Pole

The Super J-Pole Antenna(Collinear Design)

Below is a Javascript for calculating the lengths of tubing to be used for the construction of a Super J-Pole. The antenna constructed was made of 1/2" tubing.

Bottom Sectioninches
Top Sectioninches
Matching sectioninches

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Hustler 5BTV

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When I looked at the bottom of the antenna, I noticed that it could be adapted for coax feedline. So two orders  and packages later I now have the equivalent of a 5BTV. It now resides outside on the tilt-over base purchased from DX Engineering.  Here at the pond we regularly experience winds over 60mph in storms. I thought it would be prudent to have the antenna horizontal on a secure 'bed' when it was not being used. Pictures will accompany this project as it moves outside and the ground plane wires are attached.

Update: it was left upright through the winter and the winds.

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10,15,20 meter antenna

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