Question

Is it necessary for a transmitting antenna to be at the same height as that of the receiving antenna for line-of-sight communication? A TV transmitting antenna is 81m tall. How much service area can it cover if the receiving antenna is at the ground level?

Answer 1

Line-of-sight communication means that there is no physical obstruction between the transmitter and the receiver. In such communications it is not necessary for the transmitting and receiving antennas to be at the same height.

Height of the given antenna, h = 81 m

Radius of earth, R = 6.4 × 10⁶ m

For range, d = (2Rh)^½, the service area of the antenna is given by the relation:

A = πd²

= π (2Rh)

= 3.14 × 2 × 6.4 × 10⁶ × 81

= 3255.55 × 10⁶ m²

= 3255.55

∼ 3256 km²