====== Radio propagation ======

**Radio propagation** is the way radio waves travel between a transmitter and a receiver. The path depends on frequency, the environment and conditions along the route.

===== HF propagation =====

On high-frequency bands, ionospheric conditions can support communication well beyond the horizon. The time of day, season and solar activity influence which paths are available. One band can be productive while another is closed for the intended contact.

===== VHF and UHF propagation =====

At VHF and UHF, antenna height, terrain, buildings and path clearance often have a strong effect on coverage. Atmospheric conditions can also enable paths much longer than normally observed.

===== Observations =====

Useful records include frequency or band, UTC time, station locations, operating mode, antennas and signal reports. These details allow an unusual contact to be compared with other observations.

===== See also =====

  * [[amateur_radio_band|Amateur radio band]]
  * [[antenna|Antenna]]
  * [[radio_experiment|Radio experiment]]

===== Further reading =====

  * [[https://www.iaru.org/|International Amateur Radio Union]]