For sky wave propagation,the radio waves must have a frequency range in between

If the height of transmitting and receiving antennas are $80\,m$ each,the maximum line of sight distance will be $..............\,km$. Given: Earth's radius $= 6.4 \times 10^6\,m$.

$A$ carrier wave $v_{c}(t) = 160 \sin(2 \pi \times 10^{6} t) \text{ V}$ is made to vary between $V_{\max} = 200 \text{ V}$ and $V_{\min} = 120 \text{ V}$ by a message signal $v_{m}(t) = A_{m} \sin(2 \pi \times 10^{3} t) \text{ V}$. The peak voltage $A_{m}$ of the modulating signal is ..... .

Which of the following is the disadvantage of $FM$ over $AM$?

An antenna uses electromagnetic waves of frequency $5 \text{ MHz}$. For proper working,the size of the antenna should be:

If the highest modulating frequency of the wave is $5 kHz$,then the number of stations that can be accommodated in a $150 kHz$ bandwidth is