Earth curvature becomes a concern for links longer than 11 km (7 miles).
Line of sight disappears at 25 km (16 miles). Therefore, the curvature of the
Earth must be considered when determining the antenna mounting height, as
indicated in Figure
. To allow for
Earth bulge obstruction, the antennas must be raised higher off the ground,
than if the Earth were flat. Figure
illustrates this.