in a line of sight ratio communication,

Question:

in a line of sight ratio communication, a distance of about $50 \mathrm{~km}$ is kept between the transmitting and receiving antennas. If the height of the receiving antenna is $70 \mathrm{~m}$, then the minimum height of the transmitting antenna should be :

(Radius of the Earth $=6.4 \times 10^{6} \mathrm{~m}$ ).

  1. (1) $20 \mathrm{~m}$

  2. (2) $51 \mathrm{~m}$

  3. (3) $32 \mathrm{~m}$

  4. (4) $40 \mathrm{~m}$


Correct Option: , 3

Solution:

(3) $\mathrm{LOS}=\sqrt{2 h_{T} R}+\sqrt{2 h_{R} R}$

or $50 \times 10^{3}=\sqrt{2 h_{T} \times 6.4 \times 10^{6}}+\sqrt{2 \times 70 \times 6.4 \times 40^{6}}$

On solving, $h_{T}=32 \mathrm{~m}$

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