Question

Write the relation between the height of tv antenna and the maximum range up to which the signal transmitted by the antenna can be received how is this expression modified in case of line of sight of communication by space wave in which region of frequency is this mode of communication used

Answer 1

The distance d = $\sqrt{2hR}$

Explanation:

Let the height of antenna from the surface of earth is h

The radius of earth is R

Thus the distance d up to which the signal can go

d = $\sqrt{(R + h)^{2}-R^{2} }$ = $\sqrt{2hR+h^{2} }$

The value of h is very small in comparison to R , the radius of earth. Thus can be neglected

Therefore d = $\sqrt{2hR}$

As the frequency of radiations is very high , the wavelength is very small.

Thus the rays will travel straight , whereas the surface of earth is curved .

Therefore the actual area covered by the signal is somewhat lesser than this . Because the rays can go up to the curvature of earth.