Question

The propagation of radio signals is greatly influenced by

• A. troposphere
• B. ionosphere
• C. exosphere
• D. thermosphere

Answer 1

The Correct Option is B

The propagation of radio signals is greatly influenced by the ionosphere. The ionosphere is a part of the Earth's upper atmosphere, from about 30 miles (48 km) to 600 miles (965 km) up. It is distinguished by its ionized state, which means it has a high concentration of ions and free electrons. This ionized condition has a significant effect on the transmission of radio waves, making the ionosphere crucial for radio communications over long distances.

Radio waves are reflected or refracted by these ionized layers, allowing them to travel beyond the horizon and enabling communication around the globe. This capability is especially important for signals such as AM radio, certain shortwave bands, and other advanced telecommunication systems. While other layers like the troposphere, exosphere, and thermosphere have their roles, the ionosphere remains the most critical for modulating radio signal propagation effectively.