U.s. navy rigging knife
This calculator is designed to give the horizontal length of a particular dipole (including Tees) antenna, or one side of it, for the frequency chosen. Enter the desired frequency and select the desired calculation from the drop box. Click on Calculate and the optimum length for that combination will be displayed in feet and inches. Last year I put up an OCF, cut to the length of an 80-meter dipole. It is fed with 52-ohm cable and a 4:1 balun at the feed point. Here are my SWR results: 10 meters: lowest at 28.40 12 meters: less than 1.3 entire band 15 meters: 21.400 – 1.25, rising gradually to 2.4 at 21.000 17 meters: less than 1:5 entire band 20 meters: less than 1.4 ...