If the whole earth is to be connected by LOS communication using space waves (no restriction of antenna size or tower height), what is the minimum number of antennas required? Calculate the tower height of these antennas in terms of earth's radius.

Answer

A, D

Explanation

That can be done by using six antennas,
From above figure, side of triangle `= R + h` Also, altitude of triangle
`=
(sqrt(3))/2xx "side" = R`
`rArr (sqrt(3))/2(R +h) = R`
`rArr (sqrt(3)) (R+h) =2R`
`rArr R+h =2/(sqrt3)R`
`rArr h =2/(sqrt(3)) R- R~~ 0.15 R`.
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