Explain the following as applied to radio propagation. Ground wave Sky wave Line of sight

Ground Wave:

- Radio waves that travel along the Earth's surface, following its curvature.
- They are characterized by:
- Low frequencies (usually below 30 MHz)
- Long wavelengths
- Limited range due to attenuation and absorption by the ground
- Used for local AM radio broadcasting, navigation systems (e.g., LORAN), and emergency communications.

Sky Wave:

- Radio waves that are reflected back to Earth by the ionosphere, a layer of the Earth's atmosphere.
- They are characterized by:
- Higher frequencies (usually above 30 MHz)
- Short wavelengths
- Longer propagation distances than ground waves
- Used for long-distance communication (e.g., international radio broadcasting, satellite communication).

Line of Sight:

- A condition where there is a direct path between the transmitting and receiving antennas, without any obstructions.
- Requires a clear view between the antennas, as obstacles like buildings, hills, or trees can block the signal.
- Used in various applications, including point-to-point communication, cellular networks, and microwave links.