. . "Radio signal"@en . . . . "A radio signal is a radio wave used to transmit and receive messages. Radio signals travel through space in the form of waves. These waves vary in length, and each wavelength is associated with a particular radio frequency."@en . "A radio signal is a radio wave used to transmit and receive messages. Radio signals travel through space in the form of waves. These waves vary in length, and each wavelength is associated with a particular radio frequency."@en . . . .