Communication Systems

A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at \(4 \mathrm{~km}\) distance from it is \(x \times 10^{-2} \mathrm{~m}\). The value of \(x\) is __________.

(Let, radius of earth \(\mathrm{R}=6400 \mathrm{~km}\) )