Explain mechanisms of propagation of radio communication.

Radio communication deals with electronic radiation of electromagnetic energy from one point to another through atmosphere or free space. It is possible only in a certain position ofelectromagnetic frequency spectrum.  Currently, this portion includes frequencies from 9 kHz to 400 GHz.whereas there are international allocations for the radio spectrum up to 275 GHz, most of the commercial uses occur between 100 kHz and 20 GHz.  Very few experimental systems have been operated beyond 100 GHz.

Different layers of atmosphere play a role in propagating radio waves.  Atmosphere comprises four layers.  Of the four layers, ionosphere and troposphere are useful for radio communication in certain frequency ranges. Many other radio frequencies pass straight through atmosphere and can be beamed towards satellites placed in interplanetary space