Types of radio wave propagation

Radio wave propagation can occur through several mechanisms, each influencing how signals travel from the transmitter to the receiver.

Line-of-Sight Propagation (LOS): As the name suggests, this type requires a clear, unobstructed path between the transmitter and receiver. It's typical for radio waves above 70 MHz.

Ground Wave Propagation: This type occurs along the Earth's surface and is effective for medium and longwave frequencies (up to about 3 MHz). It's used for AM broadcasting and maritime communication.

Skywave Propagation: Here, radio waves are bounced back to Earth by the ionosphere, allowing long-distance communication. This is common in shortwave bands (3 to 30 MHz), where signals can travel around the globe. Ham radio operators and international broadcasters often utilize this method.

Figure 1: Illustration of "LOS," Ground Wave and "Skip" Propagation

Tropospheric Propagation: This type relies on the troposphere, the lowest layer of Earth's atmosphere, where signals can be bent or refracted. It can cause VHF and UHF signals to travel beyond the horizon, enhancing communication ranges under certain weather conditions.

Figure 2: Troposcatter propagation

Satellite Communication: Signals are sent to and from satellites orbiting the Earth. This type is essential for global communications, GPS, and broadcasting services.

Figure 3: Satellite Communication

Understanding these propagation types helps in selecting the appropriate frequencies and techniques for reliable communication.