Question

In a line of sight radio communication, a distance of about $50\, km$ is kept between the transmitting and receiving antennas. If the height of the receiving antenna is $70\,m$, then the minimum height of the transmitting antenna should be : (Radius of the Earth = $6.4 \times 10^6 m$).

• A. 40 m
• B. 51 m
• C. 32 m
• D. 20 m

Answer 1

Answer: (C)

32 m

Answer 2

Range = $\sqrt{2Rh_{T}} + \sqrt{2Rh_{R}}$
$50 \times 10^{3} = \sqrt{2 \times6400 \times 10^{3}\times h_{T}} + \sqrt{2 \times6400 \times10^{3} \times70}$
by solving $h_T = 32\, m$