The T.V. signal wave has frequency of range 54 MHz to  890MHz.These signals are frequency modulated. Their propagation is not possible through ground waves as the signals can e absorbed by the ground due to their high frequency .Their transmission is not possible through sky wave propagation since the ionosphere can’t reflect these signals back to earth.

The transmission of T.V. signal is possible -->

1. Using communication geo stationary satellite which reflect the T.V. signals back to earth.
2. Using tall receiving antenna’s which may directly intercept signals coming from transmitting antenna.

Height   of Antenna

Relationship between coverage distance and height of antenna

If PQ is T.V. transmitting Antenna of height h on the surface of earth .Due to finite curvature of earth T.V. Signal transmitting from Q cannot be received beyond S and T .The effective reception range of the T.V. broadcast is from S to T.

If SP = PT = d

R = radius of earth .

= OS =OP=OT

OQ =R +  h

Using ∆ QPS

SQ² = SP²  + PQ²

SQ² = d² + h²

In  ∆OSQ

OQ² = OS² + SQ²

(R+ h )² = R² + (d²+h²)

R² + h² +2hR = R² + (d²+h²)

2hR= d²

d= (2hR)^1/2

For T.V. signals curved area = πd²

Population Covered = Population density  x area covered .