Question

Space waves are used for line-of-sight (LOS) communication as well as satellite communication. Because of line-of-sight nature of propagation, direct waves gets blocked at some point by the curvature of the earth as illustrated in figure. If the signal is to be received beyond the horizon then the receiving antenna must be high enough to intercept the line-of-sight waves.

The maximum line of sight distance $d_{M}$ between the two antennas having heights $h_{T}$ and $h_{R}$ above the Earth is

• A. $d_{M}=1+\sqrt{2 R h_{T}}$
• B. $d_{M}=1+\sqrt{2 R h_{R}}$
• C. $d_{M}=\sqrt{2 R h_{T}}+\sqrt{2 R h_{R}}$
• D. $d_{M}=2 R h_{T}\left(1+\sqrt{2 R h_{R}}\right)$

Answer 1

Answer: (C)

The maximum Line of Sight (LOS) distance $d_{M}$ between the two antennas having heights $h_{T}$ and $h_{R}$ is $d_{M}=\sqrt{2 R h_{T}}+\sqrt{2 R h_{R}}$, where $h_{R}$ and $h_{T}$ is the height of receiving and transmitting antenna.