KF4EOK'S 2 meter super j-pole antenna build




I did a lot of research to find the best information on building a super j-pole antenna and here is what i found.

I found many sites with information that was not complete or had links that were no longer working. That is why I have made this page. I did find two sites with detailed instructions here: A nice wright up with pictures also here nice with schematics and pictures

The super J-pole antenna is a design that is a regular J-pole antenna with a 1/2 wave element mounted above with a 1/2 wave phasing harness connecting the element to the bottom part of the J-pole. The antenna can be built for any band.

My J-pole antenna is made with 1/2 inch copper pipe. The phasing harness is made from large diameter 1/4 soft copper tubing. The harness can be made by bending the tubing around a 1 1/4 pipe "U" shape, then bending it into a circle by bending it around a small coffee can 5 inch in diameter. Here is some pictures of my 2 meter coil.

2 meter coil 2 meter coil coil joint

The top element must be insulated from the bottom part of the antenna. I used a 1/2 wood dowel rod 6 inches long for my insulator by inserting it into the pipe. I had to sand down both ends so that it would fit snug into the copper pipe. It should be coated with epoxy to waterproof it. Be sure to cap off the top element and mounting stub to keep water out. Once the insulator is together I drilled holes through the 1/2 unions and the insulator so that when I installed the coil it will go through the insulator and get soldered on both sides.

insulator

The feed point for the antenna is in the same place as a normal J-pole, between the 3/4 wave element and the 1/4 wave matching stub. Attach the shield braid of the coax to the short matching stub side and the center conductor to the other side, (long side). Move the feed point up and down to find the best match with an SWR meter or antenna analyzer. Once a good match is found, secure the coax to the antenna. I used a SO-239 connector, so cables with PL-259 connectors can be connected to it.

2 meter bottom 2 meter antenna

The super J-pole built for 2 meters is around 9 feet tall, not including the the mounting mast. If constructed properly, it should give around 3 dB gain over a regular J-pole. This antenna has a surprisingly broad bandwidth, giving a VSWR of 1.5:1 or less from 140 to 150 MHz.

I will post some graphics readings from my RigExpert AA-520 antenna analyzer when I get some time to do so. I will be painting the 2 meter j-pole antenna to protect it from the elements. I will be feeding the j-pole with 50 OHm coax with a open coil of 4 to 5 turns of coax in a 4 inch coil near the feed point.

Here is a super j-pole calculator program that I made. You are welcome to use it. I am proud of my little program. I did not find any programs like this so I made my own. Enjoy. My FREE Super J-pole Calculator. et me know what you think, Thanks

My FREE Super J-pole Calculator.

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