Question

Which of the following is incorrect about sky waves?

• A. Sky waves are not used in long distance communication
• B. Their propagation takes place by total internal reflection
• C. Sky waves support the so-called AM band
• D. The frequency of sky waves ranges typically from 3 MHz to 30 MHz

Answer 1

Answer: (A)

Sky waves are not used in long distance communication

Answer 2

In the $MHz$ frequency range from a few $MHz$ upto $30$ to $40\,MHz,$ long distance communication can be achieved by ionosphere reflection of radio waves back towards the earth. This mode of propagation is called sky wave propagation.