Mention three different modes of propagation used in communications system. Explain with the help of a diagram how long distance communication can be achieved by ionospheric reflection of radio waves?

Explanation

The three modes of propagation used in
communication system are as follows.
(i) Ground wave propagation (ii) sky wave a
propagation (iii) space wave propagation.
Ong distance communication can be achieved
by using sky wave propagation or ionospheric
propagation. This propogation is utilising the e.m. waves of frequency range 3 MHz to 30 MHz.
This mode of communication is shown
in the following figure.