Question
Mention three ‘different modes of propagation used in communication system. Explain with the help of a diagram how long distance communication can be achieved by ionospheric reflection of radio waves.
Solution
Three modes of propagation of electromagnetic waves:
(i) Ground waves
(ii) Sky waves
(iii) Space waves
Sky wave propagation is used for long distance communication. In this process, radio waves are reflected by ionosphere. When radio waves of frequency range 3 MHz to 30 MHz, emitted from transmitting antenna reach the receiving antenna after reflection from the ionosphere acts as a reflector for radio waves.
