Question

A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance upto which signals can be broadcasted from this tower in LOS (Line of Sight) mode? (Given: radius of earth = 6.4 × 10⁶ m).

Options

• 65 km

• 48 km

• 80 km

• 40 km

Answer 1

65 km

Explanation:

Maximum distance upto which signal can be broadcasted

`"d"_"max" = sqrt(2"Rh"_"T") + sqrt(2"Rh"_"R")`

where h_T and h_R are heights of transmission tower and receiving antenna respectively.

Putting values R, hT and hR

d_max = `sqrt(2xx6.4xx106)  [ sqrt140 +sqrt40]`

or, d_max ≃ 65 km