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Chapter 7
Transmission
Media
Figure 7.1 Transmission medium and physical layer
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Figure 7.2 Classes of transmission media
7.1 Guided Media7.1 Guided Media
Twisted-Pair Cable
Coaxial Cable
Fiber-Optic Cable
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Figure 7.3 Twisted-pair cable
Figure 7.4 UTP and STP
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Table 7.1 Categories of unshielded twistedTable 7.1 Categories
of unshielded twisted--pair cablespair cables
600 MHz
200 MHz
100 MHz
20 MHz
16 MHz
< 2 MHz
very low
Bandwidth
LANsDigital600 Mbps7 (draft)
LANsDigital200 Mbps6 (draft)
LANsDigital100 Mbps5
LANsDigital20 Mbps4
LANsDigital10 Mbps3
T-1 linesAnalog/digital2 Mbps2
TelephoneAnalog< 100 kbps1
UseDigital/AnalogData RateCategory
Figure 7.5 UTP connector
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Figure 7.6 UTP performance
Figure 7.7 Coaxial cable
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Table 7.2 Categories of coaxial cablesTable 7.2 Categories of
coaxial cables
50
50
75
Impedance
Thick EthernetRGRG--1111
Thin EthernetRGRG--5858
Cable TVRGRG--5959
UseCategory
Figure 7.8 BNC connectors
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Figure 7.9 Coaxial cable performance
Figure 7.10 Bending of light ray
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Figure 7.11 Optical fiber
Figure 7.12 Propagation modes
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Figure 7.13 Modes
Table 7.3 Fiber typesTable 7.3 Fiber types
7/1257/125
100/125100/125
62.5/12562.5/125
50/12550/125
Type
7
100
62.5
50
Core
Single-mode125
Multimode, graded-index125
Multimode, graded-index125
Multimode, graded-index125
ModeCladding
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Figure 7.14 Fiber construction
Figure 7.15 Fiber-optic cable connectors
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Figure 7.16 Optical fiber performance
7.2 Unguided Media: Wireless7.2 Unguided Media: Wireless
Radio Waves
Microwaves
Infrared
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Figure 7.17 Electromagnetic spectrum for wireless
communication
Figure 7.18 Propagation methods
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Table 7.4 BandsTable 7.4 Bands
VHF TV,
FM radio
Sky and
line-of-sight30300 MHzVHFVHF
UHF TV, cellular phones,
paging, satelliteLine-of-sight300 MHz3 GHzUHFUHF
Satellite communicationLine-of-sight330 GHzSHFSHF
Long-range radio navigationLine-of-sight30300 GHzEHFEHF
330 MHz
300 KHz3 MHz
30300 KHz
330 KHz
RangeRange
Citizens band (CB),
ship/aircraft communicationSkyHFHF
AM radioSkyMFMF
Radio beacons and
navigational locatorsGroundLFLF
Long-range radio navigationGroundVLFVLF
ApplicationApplicationPropagationPropagationBandBand
Figure 7.19 Wireless transmission waves
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Figure 7.20 Omnidirectional antennas
Radio waves are used for multicast
communications, such as radio and
television, and paging systems.
NoteNote::
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Figure 7.21 Unidirectional antennas
Microwaves are used for unicast
communication such as cellular
telephones, satellite networks, and
wireless LANs.
NoteNote::
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Infrared signals can be used for short-
range communication in a closed area
using line-of-sight propagation.
NoteNote::
