1. 7.1 Chapter 7 Transmission Media Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 7.2 Figure 7.1 Transmission medium and physical layer

3. 7.3 Figure 7.2 Classes of transmission media

4. 7.4 7-1 GUIDED MEDIA Guided media, which are those that provide a conduit from one device to another, include twisted-pair cable, coaxial cable, and fiber-optic cable. Twisted-Pair Cable Coaxial Cable Fiber-Optic Cable Topics discussed in this section:

5. 7.5 Figure 7.3 Twisted-pair cable

6. 7.6 UTP Used in LAN, DSL, telephone lines to provide voice and data channels. UTP are classified in categories, 1 through 7. One wire carries the signal, the other is the ground reference. By twisting the wires, the effect of unwanted signals is the same on both wires, thus not affecting the difference. The number of twist per inch has some effect on the quality of the cable.

7. 7.7 Figure 7.4 UTP and STP cables

8. 7.8 Table 7.1 Categories of unshielded twisted-pair cables

9. 7.9 Figure 7.5 UTP connector

10. 7.10 Figure 7.7 Coaxial cable

11. 7.11 Table 7.2 Categories of coaxial cables

12. 7.12 Figure 7.8 BNC connectors

13. 7.13 Fiber-Optic Cables Made of glass or plastic, transmits signal in the form of light. Optical fibers use reflection to guide light through a channel. Multimode: Multiple beams in the core. Single-mode: Highly focused source of light

14. 7.14 Figure 7.10 Bending of light ray

15. 7.15 Figure 7.11 Optical fiber

16. 7.16 Figure 7.12 Propagation modes

17. 7.17 Figure 7.13 Modes

18. 7.18 Table 7.3 Fiber types

19. 7.19 Figure 7.14 Fiber construction

20. 7.20 Figure 7.15 Fiber-optic cable connectors

21. 7.21 7-2 UNGUIDED MEDIA: WIRELESS Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Radio Waves Microwaves Infrared Topics discussed in this section:

22. 7.22 Figure 7.17 Electromagnetic spectrum for wireless communication

23. 7.23 Figure 7.18 Propagation methods

24. 7.24 Table 7.4 Bands

25. 7.25 Figure 7.19 Wireless transmission waves

26. 7.26 Figure 7.20 Omnidirectional antenna

27. 7.27 Radio waves are used for multicast communications, such as radio and television, and paging systems. Note

28. 7.28 Figure 7.21 Unidirectional antennas

29. 7.29 Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. Note

30. 7.30 Infrared signals can be used for short- range communication in a closed area using line-of-sight propagation. Note