Explain the mechanisms of propagation of radio communication.
Radio communication deals along with electronic radiation of electromagnetic energy from one point to other by the atmosphere or free space. This is possible only in a definite position of the electromagnetic frequency spectrum. Currently, this portion involves frequencies from 9 kHz to 400 GHz. Though there are international allocations for the radio spectrum up to 275 GHz, mainly the commercial uses take place among 100 kHz and 20 GHz. Very little experimental systems have been operated beyond 100 GHz.
Various layers of the atmosphere play a task in propagating radio waves. The atmosphere contains four layers. Of the four layers, the troposphere and ionosphere are helpful for radio communication in definite frequency ranges. Certain another radio frequency passes straight by the atmosphere and can be beamed towards satellites replaced into the interplanetary space. Depending upon the mechanism of propagation, radio communication can be placed in four categories:
1. Sky wave or ionosphere communication
2. Line-of-sight (LOS) microwave communication limited through horizon.
3. Troposphere scatter communication
4. Satellite communication.