What terrain-related factor most affects VHF radio waves propagation?

The propagation of VHF radio waves is significantly influenced by the terrain and obstacles on the Earth's surface. VHF (Very High Frequency) radio waves can travel by line-of-sight, meaning that any obstruction such as hills, buildings, mountains, or other structures can block or refract these signals. In flat terrain, VHF signals can travel long distances, while in areas with rugged or uneven terrain, the effective range can be reduced due to these obstructions.

Additionally, terrain can also impact how radio waves bounce and bend, potentially allowing signals to reach locations that are otherwise out of sight. Therefore, understanding the layout of the land and any potential barriers is crucial for predicting how well VHF signals will propagate in a given area, making terrain and obstacles the most critical factors influencing VHF radio wave behavior.