What is HF Radio Propagation?
HF radio propagation is the transmission and reception of radio signals at high frequencies (HF), typically in the range of 3 MHz to 30 MHz. These frequencies are used for long-range communication over distances ranging from hundreds to thousands of kilometers.
HF radio waves are able to travel long distances by bouncing off the ionosphere, a layer of the Earth's upper atmosphere that is ionized by solar radiation. The ionosphere is made up of several layers of ionized gas, each with different characteristics that affect how radio waves are reflected back to the Earth's surface.
During the day, the ionosphere is affected by the sun's radiation and becomes more ionized, which means that radio waves at certain frequencies are more likely to be reflected back to Earth. At night, the ionosphere becomes less ionized, and the frequencies that are reflected back to Earth shift to lower frequencies.
The behavior of the ionosphere is affected by a number of factors, including the time of day, the season, and the location of the transmitter and receiver. As a result, HF radio propagation can be affected by a range of environmental conditions, including solar activity, geomagnetic storms, and weather conditions.
HF radio is used by a variety of organizations, including amateur radio operators, military and government organizations, and commercial operators such as airlines and shipping companies. Despite the development of new communication technologies, HF radio remains an important method of long-range communication, particularly in remote areas where other forms of communication are not available.
You may find more detailed information in the main webpage, here. See also an index for HF Radio Propagarion.