Earth–ionosphere waveguide Earth and the ionosphere. The round-the-world nature of the waveguide produces resonances, like a cavity, which are at ~7 Hz. Radio propagation within the ionosphere depends on frequency, angle of incidence, time of day, season, Earth's magnetic field, and solar activity. At vertical incidence, waves with frequencies larger than the electron plasma frequency (f) of the F-layer maximum (1) f = 9 (N) kHz (N in cm is the electron density) can propagate through the ionosphere nearly undisturbed. Waves with frequencies smaller than f are reflected within the ionospheric D-, E-, and F-layers. f is of the order of 8–15
Radio Waves (song) Radio Waves (song) "Radio Waves" is the opening track from Roger Waters' second solo studio album, "Radio K.A.O.S." It was chosen as the lead single for the album, released worldwide in May 1987. "Radio Waves" introduces the main character, Billy, a disabled man who finds a way to talk and become friends with a radio DJ. Billy is gifted and has the miracle of hearing and interpreting radio waves in his head. He explores a cordless phone which was hidden in his wheelchair by his brother Benny, after destroying and robbing a store. Recognising its similarity to a radio, he