Radio waves in the VHF and higher frequency bands propagate mainly as which type of waves?

Radio waves in the VHF (Very High Frequency) and higher frequency bands primarily propagate as space waves. This type of wave behavior is characterized by direct line-of-sight transmission, meaning the waves travel in straight paths from the transmitting antenna to the receiving antenna. Space waves are capable of traveling over the horizon, particularly if there are elevated antennas, allowing them to reach distances beyond the visual range.

In contrast, sky waves are primarily associated with frequencies in the HF (High Frequency) band and rely on reflection off the ionosphere to extend their range. Earth reflected waves involve signals bouncing off the Earth's surface, which can sometimes occur in lower frequency bands but are less relevant to VHF and higher frequencies. Surface waves are typically associated with low-frequency signals that travel along the surface of the Earth and are not suitable for VHF ranges due to their higher attenuation over distance. Therefore, space waves are the predominant mode of propagation for VHF and higher frequency radio communications, making this the correct choice.