Propagation Below 100 kHz

At frequencies below 100 kHz radio waves that have traveled a great distance act as though they propagated in the space between two concentric, spherical, conducting-mirror shells consisting of the lower edge of the ionosphere and earth. Propagation at these low frequencies differs from propagation at higher frequencies in that skywave signals are able to penetrate the ionosphere only very slightly, ionospheric energy absorption is relatively small, and groundwave attenuation is so small that appreciable-strength groundwave signals can be received up to about 1000 km. ©2004 Tigertek, Inc. All rights reserved.

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