🔍 Key Concepts

• VHF radio frequency range and how it normally propagates • Difference between ground/space wave, tropospheric, and ionospheric (skywave) propagation • Which ionospheric layers (D, F1, F2) affect HF vs VHF communications

💭 Think About

• Ask yourself: Does VHF (marine channels around 156–162 MHz) usually bounce off the ionosphere the way HF does, or does it mostly travel line‑of‑sight? • Which phenomenon would let a normally line‑of‑sight signal be received at much greater than normal range along the Earth’s surface? • Would simply increasing transmitter power change the distance the signal can bend around the Earth, or mostly just how strong it is within normal range?

✅ Before You Answer

• Confirm the typical frequency ranges that are affected by ionospheric F1/F2 layer skywave propagation (HF vs VHF). • Check which layer (D layer vs F layers vs troposphere) is associated with long‑distance VHF reception beyond the horizon. • Verify whether a change from 1 W to 25 W actually changes propagation mode, or just signal strength.