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Ð ÐSignals can travel through sky propagation, ground propagation, or line-of-sight propagation

                 Ð ÐThe electromagnetic spectrum used for wireless communication ranges from 3 kHz to 900 THz.
                 There are mainly three types of unguided media which are as follows:

                 Radio Waves
                 Radio waves are electromagnetic impulses that can move in any direction through empty
                 space.  As  radio  waves  are  omnidirectional,  messages  can  travel  in  any  direction.  Due  to
                 the omnidirectional nature of radio waves, they can be interfered with if another receiving
                 antenna sends out a signal with the same frequency or bandwidth. The frequency range of
                 radio radiation is 3 kHz to 1 GHz. In case the transmitting and receiving antennas are not
                 aligned, so any receiving antenna can pick up the wave that the sending antenna sends.
                 Microwaves
                 The electromagnetic wave used in microwave communication has a frequency range of about (1–300GHz). With regard
                 to sight, electromagnetic waves only travel in one way, preventing any intrusion. Line of sight and communication
                 between the two endpoints are much simpler to create when the transmission medium is in alignment.
                 There are two types of microwave transmission which are as follow:

                 •   Terrestrial Type Microwave Transmission: Terrestrial Type Microwave Transmission with the propagation of the
                   microwave, which is primarily used for telecommunication over the air, both antennas are fixed for the signal
                   transfer on the transmitting and receiving sides.

                    Highly directional antennas are used for line-of-sight propagation routes. Transmission frequencies are in the range
                   4 to 12 GHz. Depending on their distance, the antennas’ diameters can range from 12 inches to several feet and are
                   typically parabolic.

                                                                        Signals

                                   Microwave
                                    antenna






                                                                  Terrestrial Microwave
                 •   Satellite  Type  Microwave  Transmission:  The  electronic  wave  used  in  satellite-type  microwave  transmission  is
                   electromagnetic in nature and is transmitted by a source. The source contains transmitting antennae, which amplify
                   the source wave—a signal—and rebroadcast it to the recipient antennae. One of the finest satellite type microwave
                   transmission applications is the Global Positioning System (GPS).
                                                                    Satellite






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                                               First Earth Station          Second  Earth Station

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