HF Propagation Basics
HF propagation is what makes long-distance radio communication possible on the HF amateur radio bands.
Signals on these frequencies can travel far beyond the horizon by interacting with the ionosphere.
What is this page about?
This page explains the basic ideas behind HF propagation and why band conditions change from day to day and hour to hour.
How HF Signals Travel
HF signals can reflect or refract through layers of the ionosphere and return to Earth at distant locations.
This is why an HF signal may travel across a province, across a continent, or around the world.
What Affects HF Propagation
- Solar activity
- Time of day
- Season of the year
- Frequency band in use
- Geomagnetic activity
Why Conditions Change
Different bands open and close depending on ionospheric conditions. Some bands work best during the day, while others perform better at night.