In radio communication, we use several terms to describe the type of wave that is being transmitted and received. Here's a detailed explanation of the main types:

1. Line-of-Sight (LOS) Wave

• Characteristics: Signals travel in a straight line from the transmitter to the receiver.
• Range: Limited by terrain features such as mountains, hills, or buildings.
• Propagation: Typically used for short-range communications.

2. Ground Wave

• Characteristics: Signals travel along the surface of the Earth, following the curvature of the planet.
• Range: Limited by distance and terrain features, typically up to 100-200 km (62-124 miles).
• Propagation: Commonly used for low-frequency (LF) and medium frequency (MF) communications.

3. Space Wave

• Characteristics: Signals travel through the air, following a straight line from the transmitter to the receiver.
• Range: Limited by atmospheric conditions such as ionization, scattering, and absorption.
• Propagation: Typically used for high-frequency (HF), very high frequency (VHF), and ultra-high frequency (UHF) communications.

4. Ionospheric Wave

• Characteristics: Signals travel through the ionosphere, a layer of the atmosphere that contains charged particles.
• Range: Can be long-distance, up to 20,000 km (12,427 miles) or more.
• Propagation: Typically used for shortwave radio communication and amateur radio.

5. Reflected Wave

• Characteristics: Signals are reflected off the surface of the Earth or other surfaces before reaching the receiver.
• Range: Can be long-distance, depending on the reflecting surface.
• Propagation: Commonly used in ionospheric propagation and over-the-horizon (OTH) communication systems.

6. Skywave

• Characteristics: Signals travel through the ionosphere, bouncing off the Earth's surface before reaching the receiver.
• Range: Can be long-distance, up to 20,000 km (12,427 miles) or more.
• Propagation: Typically used for shortwave radio communication and amateur radio.

7. Ground Effect

• Characteristics: Signals are amplified by being reflected off the surface of the Earth.
• Range: Limited by distance and terrain features.
• Propagation: Commonly used in low-frequency (LF) and medium frequency (MF) communications.

To illustrate these concepts, here's a rough estimate of signal ranges for different frequencies:

Frequency	Line-of-Sight	Ground Wave	Space Wave
10 MHz	Short range (<100 km / <62 miles)	Medium range (100-500 km / 62-310 miles)	Long
range (>1,000 km / >621 miles)
20 MHz	Medium range (100-500 km / 62-310 miles)	Long range (>1,000 km / >621 miles)	Very
long range (>5,000 km / >3,107 miles)
30 MHz	Short range (<100 km / <62 miles)	Medium range (100-500 km / 62-310 miles)	Long
range (>1,000 km / >621 miles)

Keep in mind that these estimates vary depending on the specific propagation conditions and terrain features.