Part II. Physical Layer and Media Chapter 7. Transmission Media COMP 3270 Computer Networks Computing Science Thompson Rivers University

Learning Objectives List the three types of guided media. State the reason why higher frequency radio band can transfer more data.

Transmission medium and physical layer

Classes of transmission media

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:

Twisted-pair cable Twisting: to reduce the mutual interference

UTP and STP cables Unshielded Twisted Pair Shielded Twisted Pair

Categories of UTP cables

Coaxial cable

Categories of coaxial cables

BNC connectors

Optical Fiber

Bending of light ray

Optical fiber

Propagation modes

Using reflection Using refraction These days

Fiber-optic cable connectors

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:

Electromagnetic spectrum for wireless communication 30 GHz Microwave

Propagation methods DiffractionReflection

Bands

Wireless transmission waves ~ 30 G ~ 300 G ~ 400 THz

Omnidirectional antenna

Unidirectional antennas