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 Figure 7.4 UTP and STP cables Example: Ethernet, phone line

7. 7.7 UTP cables 1 – Jacket 2 – Solid twisted pair 3 – Spacer

8. 7.8 SSTP cables 1 – Jacket 2 – Shield-braid 3 – Shield-foil 4 – Stranded twisted pair

9. 7.9 Figure 7.5 UTP connector

10. 7.10 Figure 7.7 Coaxial cable

11. 7.11 Figure 7.8 BNC connectors

12. 7.12 Twisted-pair cable vs. coaxial cable Bandwidth: coaxial > twisted-pair Transmission distance: twisted-pair > coaxial Thus cable needs frequent use of repeaters.

13. 7.13 Figure 7.10 Bending of light ray

14. 7.14 Figure 7.11 Optical fiber This is the reason why optical fiber cannot be bended arbitrarily.

15. 7.15 Figure 7.14 Fiber construction

16. 7.16 Figure 7.15 Fiber-optic cable connectors

17. 7.17 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:

18. 7.18 Figure 7.17 Electromagnetic spectrum for wireless communication

19. 7.19 Electromagnetic spectrum for wireless communication

20. 7.20 Figure 7.18 Propagation methods

21. 7.21 Table 7.4 Bands

22. 7.22 Figure 7.19 Wireless transmission waves

23. 7.23 Figure 7.20 Omnidirectional antenna

24. 7.24 Example: Omnidirectional antenna Use: Wireless router

25. 7.25 Radio waves are used for multicast communications, such as radio and television, and paging systems. Note

26. 7.26 Figure 7.21 Unidirectional antennas

27. 7.27 Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. Note

28. 7.28 Infrared signals can be used for short- range communication in a closed area using line-of-sight propagation. Note

29. 7.29 Example: Unidirectional Anntena Use: Wireless link connecting two remote WLANs

30. 7.30 Example: Homemade Unidirectional Antenna - Can antenna

31. 7.31 Example: Homemade Unidirectional Antenna Use: Cellular Anntena Tower

32. Advantages and Disadvantages Wireless Communication Advantages User Mobility Easy to install Reduced cost Scalability Disadvantages High data error rate Lower transmission data rates Security Battery of Mobile Devices Health Issues