How far above the ground and other obstacles do the antennas need to be is determined by the diameter of the Fresnel zone. The diameter of the Fresnel zone depends upon the frequency and distances between the two radios. Various data points were inserted into Fresnel zone formulas to provide some points of reference. The following table provides approximate Fresnel zone diameters at 1000 feet, 1 mile, 5 mile and 10 mile ranges. In order to have ground clearance, the combined antenna height should be equal to the diameter of the Fresnel zone.