DIY: 2m Slim Jim J-Pole Antenna

Hombrew 2m Slim Jim J-Pole Antenna: Tutorial

w/ Pictures

Materials Needed

  • 450 Ohm ladder line
  • 12AWG Wire
  • RG-58 Cable
  • Zip ties
  • Solder and solder gun
  • Crimp Ring Terminal (optional)

I would like to give credit to Mike, call sign MØMTJ. He is from the UK and with the help of the interwebz, I was able to find his tutorial on how to build a 2m Slim Jim J-Pole Antenna. He has a lot of awesome content. Check out his page to see some cool projects.

1.You want to figure out what frequency you want your antenna to operate on. You can use the calculation 234/freq = 1/4 wave length of the 450 Ohm ladder line and 468/freq. = 1/2 wave length for the 12AWG wire.This antenna is made of a 1/2 wave length and a 1/4 wave length. You will need these two lengths. Write these measurements down as a reference for later. For this DIY, I used frequency 146 MHz.

2. Before cutting the actual length, lets start with the ladder line. Strip off about 1 inch off the bottom of the ladder line on both sides. Solder the 2 ends of the ladder line. This will be the bottom side.


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**Note: I added a small piece of heat shrink tubing before I soldered the wire together to insulate the soldered wires. This step is optional. You can also just use electrical tape.

3. You can now cut the 1/4 wave length of the ladder line according to Step 1.

4. Grab your 12AWG wire and cut it to the 1/2 wave length of Step 1.

5. Prepare the 12AWG wire by stripping about 3/4 of an inch from one side.

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6. Do the same for the ladder line on the top side. Strip back about 3/4 of an inch and connect it with the speaker wire. Solder the two wires together and add a small piece of heat shrink tubing for insulation.

**Note: I added a zip tie for extra support and stability. It is not needed, but I do highly recommend it.

Connect and solder the two wires.
Heat shrink tubing for insulation.
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Add a zip tie for extra support.

7. Now for the RG-58 coax. The length of this cable is entirely up to you. It is recommended that it does not exceed 25ft. I used 15ft of RG-58 for my antenna.

8. Strip of the jacket of the coax about 1 1/2 inches on one end. Take the outer shielding of the cable and twist it. The center conductor will have a plastic insulator and you will have to strip that off to expose about 3/4 of an inch of bare wire.

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9. On the bottom of the ladder line measure about 1.37 inches and strip about 1/4 inch to expose the bare wire on each side.

Warninig! Be careful not to cut through the wire in this step. I found that an exacto knife works well in this step.

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9.  Solder the center conductor to the side that has the 12AWG wire soldered to it.

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The center conductor is soldered to the left side which has the 12AWG wire.

10. Add some electrical tape to keep the coax from coming apart from the ladder line.

11. Add a balun about 2 inches below the ladder line using the same coax. (This should be about 6-8 turns, 1 inch in diameter). You can see the example of the balun in the last picture.

12. I added a ring terminal to the top of the 12AWG wire so that I can suspend it from anywhere. For example. In my home, I hang this antenna from a thumb tack on the wall. If I am in the field, I can add some paracord and hoist it up a tree.


Now your antenna is complete.

2m Slim Jim J-Pole Indoors.
2m Sim Jim J-Pole Outdoors.

To see my Field Ready System, click here.



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