The waves which are reflected back to the earth by the ionosphere are:

If the sum of heights of transmitting and receiving antennas in line of sight communication is $h$,then the height of the receiving antenna,to have the maximum range,is

For effective transmission of a wave with frequency $3000 \text{ kHz}$,the minimum length of the antenna should be ...... $m$.

If in an amplitude modulated wave,the maximum amplitude is $14 \ V$ and the modulation index is $0.4$,then the amplitude of the carrier wave is (in $V$)

$A$ baseband signal of $3.5\, MHz$ frequency is modulated with a carrier signal of $3.5\, GHz$ frequency using amplitude modulation. What should be the minimum size of antenna required to transmit the modulated signal?

In an $AM$ detector circuit,$R = 2 \text{ k}\Omega$ and $C = 1 \mu\text{F}$. This circuit will demodulate a carrier frequency of ......... $\text{kHz}$ effectively.