Question

Mention two different modes of propagation used in communication system.

Hint:

Ground wave = Travels along the Earth's surface (used in AM radio). Space wave = Direct line-of-sight propagation (used in satellite communication).

Answer 1

In communication systems, different modes of propagation are used to transmit signals from one point to another. Two main modes of propagation are:
1. Ground Wave Propagation:
- In this mode, radio waves travel along the surface of the Earth. The waves follow the curvature of the Earth, making ground wave propagation ideal for long-range communication. Ground waves are typically used for AM radio broadcasting, where signals are transmitted at low frequencies and propagate along the ground. This method is especially useful for communications in the range of 30 Hz to 3 MHz.
- Example: AM radio signals use ground wave propagation.
2. Space Wave Propagation:
- In space wave propagation, radio waves travel through the atmosphere in a direct path from the transmitter to the receiver, usually over line-of-sight distances. This mode is used for high-frequency signals, including microwaves and satellite communication. Space wave propagation does not rely on the Earth’s surface but instead travels through the air, making it suitable for both terrestrial and satellite communication.
- Example: Satellite communication uses space wave propagation.
In summary, the two main modes of propagation in communication systems are ground wave propagation and space wave propagation, each suitable for different frequency ranges and communication needs.