Height h of transmitter antenna when R is radius of earth to have range d is

$\frac{d^2}{2R}$ $\sqrt{2dR}$ $\frac{2d^2}{R}$ $\frac{2R^2}{d}$

$\frac{d^2}{2R}$

$d = \sqrt{2hR} \, or \, h = \frac{d^2}{2R}$