3. radio is the medium that is used to send signals into the air, and can be sent in both near and far with the broadcasting (broadcast) is sent to the receiver, and the use of radio waves in the frequency range of various.
3. radio as a medium to send signals into the air. You can send both near and far distances. The signal (broadcast) transmitted to the receiver. And use the radio frequency range.
3. Radio waves. As a medium using signal over the air. By the way can be sent in both near and far, by a signal distribution (broadcast) sent to the receiver, and use radio waves in the frequency range.