The waves used for line-of-sight $(LOS)$ communication are

In which frequency range are space waves normally propagated?

The maximum distance up to which $TV$ transmission from a $TV$ tower of height $h$ can be received is proportional to

The audio signal used to modulate $60 \sin(2\pi \times 10^6 t)$ is $15 \sin(300\pi t)$. The depth of modulation is.......$\%$

$A$ $TV$ tower has a height of $150 \ m$. If the population density around the $TV$ tower is $10^3 \ km^{-2}$, then the population covered by the tower is (Radius of the earth, $R = 6.4 \times 10^6 \ m$). (in $\text{lakh}$)

What should be the height of a transmission antenna (in $m$) to cover a range of $128 \, km$?