Question:
For VHF signal broadcasting, ___________- $\mathrm{km}^{2}$ of maximum service area will be covered by an antenna tower of height $30 \mathrm{~m}$, if the receiving antenna is placed at ground. Let radius of the earth be $6400 \mathrm{~km}$. (Round off to the Nearest Integer) (Take $\pi$ as $3.14$ )
Solution:
$\mathrm{d}=\sqrt{2 \mathrm{Rh}}$
$\mathrm{A}=\pi \mathrm{d}^{2}$
$\mathrm{~A}=\pi 2 \mathrm{Rh}$
$=3.14 \times 2 \times 6400 \times \frac{30}{1000}$
$\mathrm{A}=1205.76 \mathrm{~km}^{2}$
$\mathrm{~A} \simeq 1206 \mathrm{~km}^{2}$