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)

Answer 1

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, h_T = 20 m and height of receiving antenna, h_R = 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.