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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
Basics of Networking and Web Architecture 115

