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Question
Name the type of waves which are used for line of sight (LOS) communication. What is the range of their frequencies?
A transmitting antenna at the tope of a tower has a height of 20 m and the height of the receiving antenna is 45 m. Calculate the maximum distance between them for satisfactory communication in LOS mode. (Radius of the Earth = 6.4 × 106 m)
Solution
Space wave are used for the line of sight (LOS) communication.
The range of their frequencies is 40 MHz and above.
We have, height of transmitting antenna, hT = 20 m and height of receiving antenna, hR = 45 m
Then, Maximum distance between the two antennas,
`d_m = sqrt(2Rh_r) + sqrt(2Rh_R)`
`=> d_m = sqrt(2 xx 6.4 xx 10^6 xx 20) + sqrt(2 xx 6.4 xx 10^6 xx 45) = 2 xx 8 xx 10^3 + 3 xx 8 xx 10^3 = 40 km. `
Thus, the maximum distance between the antennas is 40 km.
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