This calculator is designed to give the critical information of a particular beam antenna, in this case a three element Yagi, for the frequency chosen. Enter the desired frequency then click on Calculate and the optimum values for that combination will be displayed in feet, inches and fractions of inches, and in meters. To optimize the antenna for a frequency RANGE, do the calculations twice, once for the low end of the range and once for the high end; then average the two and plan to adjust the VSWR on both ends of the range as needed. As general information, the director is the shortest element, the driven element is the middle element (in a 3 element beam) and the reflector is the longest element. Spacing is on the antenna bar holding the elements, with equidistant spacing from each of the outside elements to the driven element. Direction of the strongest transmitted signal is from the reflector toward the director. Reception is the reverse.