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
The Tidal Waves The Tidal Waves The Tidal Waves were an American garage rock band formed in Roseville, Michigan, in 1964. Despite the young ages of the group members, the Tidal Waves were one of the more accomplished musical acts in the bustling Michigan garage band scene. They are best remembered for their regional hit, a cover version of "Farmer John", which managed to reach the Top 10 of several radio station charts around Detroit. Inspired by the Beatles' momentous appearance on "The Ed Sullivan Show" in February 1964, high school students Tom Wearing (drums, vocals), Mark Karpinski (lead guitar, vocals), and Vic