High-frequency (HF) radio signals ranging from 3 to 30 MHz propagate by refracting off the ionosphere, facilitating long-distance communication. During the day, the ionosphere becomes more ionized, with higher frequencies bounced back to Earth. At night, it becomes less ionized, with lower frequencies bounced back to Earth.The project "Understanding HF Propagation," focuses on skywave propagation, shows near-real-time indices and explains what the terms mean. |