Question

Write a short note on sky wave propagation.

Answer 1

Hint: The low radio waves frequencies are transmitted using ground wave propagation. For sky wave propagation, we need higher frequencies which can travel to long distances in the atmosphere without much distortion.

Complete step-by-step answer:
Long distance communication is necessary for connecting different parts of the world. The transmission of information from one place to another is done via electromagnetic waves mainly radio waves. There are three ways through which long distance communication has been made possible.
1. Ground wave propagation
2. Sky wave propagation
3. Space wave propagation
In the sky wave propagation, the radio waves are sent towards the higher layers of atmosphere which reflects the waves back towards earth covering a larger distance than ground waves. The sky wave propagation relies on the reflection of radio waves from the charged ions in the ionosphere. The ionosphere ions can only vibrate at a certain range of frequencies and hence are suitable for frequency range 3MHz to 30MHz.

Additional Information: In ground wave propagation, the radio waves travel near the surface of earth but this method is not useful for too long distances. Surface waves also come under this category and travel near the surface of earth.
In space wave propagation, the radio waves are sent beyond the atmosphere towards the satellites revolving around earth which reflect the waves back over longer distances.

Note: The ultra-high frequencies have very large frequencies which can neither be reflected by the ions in the ionosphere or can travel near ground. Due to this, the UHFs are transmitted through space wave communication where we use satellites for reflecting waves back to earth.