I built this J-Pole antenna for GMRS radio. I started with calculations available online for the frequency I wanted to target, in my case 462mhz. I bought some #4 solid copper wire from the big box store and cut the long piece to specs. Then I cut and bent a shorter piece to specs. The pictures tell the story. Using a propane torch I soldered the two pieces to form the "J" in J-Pole. I then soldered the center wire and coax cable braid where indicated by the calculations. (Note the braid is soldered to the short leg, part "B"). Let me point out here that if you are using garbage coax with a steel core wire and who knows what kind of braid you may not be able to solder it. Do yourself a favor and buy at least a pole length of real copper coax to construct the antenna, at least use good wire to the first grounding block. I don't run coax into a building without grounding it outside, it may just give lightning some place to go other than your living room. No guarantees but it's better than nothing. To protect it from being bent or damaged while mounted on top of a pole I used different sizes of pvc pipe and connectors to fit over the antenna. Right at the point where the coax passes through a hole in the pvc pipe to the soldered connection on the J-Pole I did six wraps around a short piece of pvc pipe and zip tied it to form a choke. I then mounted it on a pole next to my barn. In my case I already had a yagi directional antenna so I mounted it on the same pole with a separate coax cable for when I want directional transmission, I just switch antennas. SPECIAL NOTE FOR THE LAWYERS: This little blog shows how I did it. If you fall off your roof, set yourself on fire, chop off your finger with a wire cutter, it's on you brother. Ain't my problem.
