The J-Pole antenna is fundamentally an end-fed 1/2-wavelength antenna that uses a 1/4-wavelength long transformer section to supply the feed voltage. It is an ideal end-mounted, single-mast antenna. It is cheap and easy to build, sturdy, very easy to tune up, and performs quite well. The antenna to the left is made from 1/2" copper tubing and it is soldered together with (1) plumbing tee and (1) elbow. A plastic cap or copper nipple can be used on the tops to keep out water. The coax (RG-8 or equiv.) can be soldered to the pipe or attached with moveable conductive clamps (recomended). This antenna needs no impedance matching if you use 50 ohm coax since the resistance/reactance appears to be around 50 ohms. Once you have it mounted and connected to your radio slide the center conductor clamp up or down and note the SWR reading. If the SWR cannot be lowered to the desired reading you may have to cut or lengthen the "A" section. Shortening the antenna will raise the resonate frequency. Experiments have shown that it is possible to get a 1:1 reading with this antenna.