HF skywave propagation tutorial
for radio amateurs

Radio amateurs use various propagation modes.

For example:
1. Space Wave propagation is the direct radio wave transmission in a line-of-sight.
2. Ground Wave Propagation (surface waves) is a property that allows communication even behind a hill or across the horizon.
3. Skywaves enable communication over extremely long distances, sometimes on the other side of the globe.

Figure 1: Illustration of "LOS," Ground Wave and "Skip" Propagation

How is skywave propagation possible?

Skywaves travel through the Earth's upper atmosphere via multi refractions of the ionosphere.

Figure 2: Ionosphere (Thermosphere) is part Earth's Atmosphere

Sunopots Pictures were published by UCAR - Center for Science Education


Figure 3: Two images of the Sun (February 3, 2002)
by Solar and Heliospheric Observatory (SOHO) satellite🗗
courtesy of European Space Agency and NASA.
See explanations here

A number of variables, such as the time of day, the seasons, and solar activity, have an impact on HF radio propagation. During the day HF radio waves travel longer distances than at night.

In conclusion, HF radio propagation is an important topic for radio amateurs who use HF bands for communication. Successful HF radio communications require an understanding of the various propagation modes and the elements that govern HF radio propagation.

See a table of contents.
See also an index of terms for HF Radio propagation.