Antenna Height Calculator

Required Tower Height is proportional to the square of the remaining distance the tower alone must cover after subtracting the horizon reach already provided by the remote antenna's own height. Because it's a squared relationship, not a linear one, doubling your target coverage distance increases the tower height needed by far more than double -- the often-cited "roughly quadruples" rule of thumb only holds when the remote antenna's height is small relative to the target distance; when it isn't, the increase can be considerably steeper than 4x, since the remaining distance the tower must cover grows faster than the target distance itself. This is why long point-to-point radio links favor tall towers and short hops rather than one enormous single link.

The K-factor scales the earth's true radius to an "effective" radius that accounts for how a standard atmosphere gradually bends radio waves toward the ground, letting them travel slightly farther than a straight geometric line would suggest. The commonly used standard-atmosphere value is 4/3 (about 1.333); it can shift under unusual weather (temperature inversions or humidity gradients), occasionally making paths that work most days unreliable during those conditions.

Not necessarily. This calculator checks pure geometric clearance -- whether the direct line between antennas clears the curved earth -- but a working RF link also needs adequate Fresnel-zone clearance around that line, since diffraction loss can degrade a link even when the direct line itself is unobstructed. The 1st Fresnel Zone Radius this calculator reports (at 2.4 GHz) gives a sense of how much additional clearance around the direct path matters at that frequency.

Total Distance is covered by two horizon reaches added together: the distance the remote antenna's own height lets it see toward the tower, and the distance the tower must independently cover to close the remaining gap. Raising the remote antenna's height increases its own horizon reach, which shrinks the distance left over for the tower to cover -- and since required height scales with the square of that remaining distance, even a modest increase in remote height can meaningfully reduce the tower height needed.