Question

Frequencies in the UHF range normally propagate by means of (A) ground waves (B) sky waves (C) surface waves (D) space waves

Short answer

The Ultra High Frequency (UHF) range, which includes frequencies between 300 MHz and 3 GHz, primarily propagates through (D) space waves, also known as line-of-sight waves or direct waves. These waves can travel in a straight line between transmitter and receiver, passing through the Earth's atmosphere without being absorbed or reflected, making them suitable for UHF communications such as microwave links, mobile phone networks, and satellite communications. Other wave types like ground waves, sky waves, and surface waves are not the primary methods of propagation for the UHF range.

Step-by-step solution

Understanding UHF range

The Ultra High Frequency (UHF) range includes electromagnetic waves with frequencies between 300 MHz and 3 GHz. These frequencies are commonly used for television broadcasting, mobile phones, GPS, and various other communication systems.

Ground Waves Propagation

Ground waves are low-frequency radio waves that travel along the Earth's surface and follow its curvature. They are mainly used for AM radio and long-distance shortwave communications. Ground waves lose their strength due to the conductivity of the Earth's surface and attenuation. The ground wave propagation is not the primary method for UHF frequency range.

Sky Waves Propagation

Sky waves, also known as ionospheric waves, bounce off the ionosphere and back to the ground. These waves are used for long-distance communication on lower frequencies (up to 30 MHz) such as shortwave radio. Sky waves are not suitable for UHF propagation as they don't efficiently bounce off the ionosphere at higher frequencies.

Surface Waves Propagation

Surface waves are electromagnetic waves that are guided along a conducting surface like a wire. This type of wave propagation is mostly used in guided transmission lines and is typically not associated with wireless radio frequency (RF) propagation like UHF. So, this option doesn't apply to UHF range.

Space Waves Propagation

Space waves, also known as line-of-sight waves or direct waves, travel in a straight line from the transmitter to the receiver. They are responsible for VHF (Very High Frequency) and UHF propagation because they can pass through the Earth's atmosphere without being absorbed or reflected. Space wave propagation is common for communications in the UHF range, such as microwave links, mobile phone networks, and satellite communications. Based on the understanding of different types of waves propagation and their suitability for the UHF range, we can conclude the correct answer. Answer: (D) space waves.