Question

Explain, with the help of a suitable diagram, the space wave mode of propagation. Give two examples in communication systems where this mode is used. What is the frequency range of these waves? Give reason for using this range of frequency.

Answer 1

A space wave travels in straight line from a transmitting antenna to a receiving antenna. They are used for transmitting frequency signals above 40 MHz. Space waves are used for line of sight communication as well as satellite communication. The propagation of signal through a space wave is shown below:

Space wave mode of propagation is used in:
(i) Television broadcast
(ii) Satellite communication
The frequency range for these waves is 40 MHz or above. The reason for using this range of frequency is that at frequencies above 40 MHz, the antennas are relatively smaller and can be placed at heights of many wavelengths above the ground.