Propagation

This section introduces the many ways radio waves travel through and around Earth’s atmosphere. Students learn about line-of-sight, ground wave, and ionospheric wave propagation, then explore more advanced effects like skip, fading, sporadic-E, aurora, tropospheric ducting, and scatter. The lessons explain how solar activity, sunspots, and the 11-year solar cycle shape HF conditions, while also showing how VHF and UHF signals can extend beyond line-of-sight through atmospheric effects. By understanding propagation, amateur operators can predict when bands will open, what frequencies will carry farthest, and why signals fade or distort.