The document discusses various types of transmission media used in data communication, including guided media (like twisted-pair, coaxial, and fiber-optic cables) and unguided media (such as wireless transmission). It outlines the characteristics, advantages, and disadvantages of each type, highlighting the features such as cost, ease of installation, and applications for different cable types. Additionally, the document explains the functioning of wireless transmission, including radio waves, microwaves, and infrared signals.

1. Transmission Media
Presented by,
V.Santhi,
Assistant Professor,
Department of Computer Applications,
Bon Secours College for Women, Thanjavur

2.  In data communication terminology, a
transmission medium is a physical path
between the transmitter and the receiver
i.e. it is the channel through which data is
sent from one place to another.

3. Types of Transmission Media

4. GUIDED MEDIA
It is also referred to as Wired or Bounded transmission
media. Signals being transmitted are directed and
confined in a narrow pathway by using physical links.
Features:
 High Speed
 Secure
 Used for comparatively shorter distances
Twisted-Pair Cable
Coaxial Cable
Fiber-Optic Cable
Types of Guided Media:

5. Twisted pair
 Twisted pair is a physical media made up of a
pair of cables twisted with each other.
 A twisted pair cable is cheap as compared to
other transmission media.
 Installation of the twisted pair cable is easy, and
it is a lightweight cable.
 The frequency range for twisted pair cable is
from 0 to 3.5KHz.
 A twisted pair consists of two insulated copper
wires arranged in a regular spiral pattern.
7.5

6. 7.6
Twisted-pair cable

7. Twisted pair
7.7

8. Types of Twisted pair:
7.8

9. Unshielded Twisted Pair
7.9
 An unshielded twisted pair is widely used in
telecommunication.
 UTP consists of two insulated copper wires
twisted around one another. This type of cable
has the ability to block interference and does not
depend on a physical shield for this purpose. It
is used for telephonic applications.


10. Unshielded Twisted Pair
 Category 1: Category 1 is used for
telephone lines that have low-speed data.
 Category 2: It can support upto 4Mbps.
 Category 3: It can support upto 16Mbps.
 Category 4: It can support upto 20Mbps.
Therefore, it can be used for long-distance
communication.
 Category 5: It can support upto
200Mbps.
7.10

11. Advantages Of Unshielded Twisted Pair:
 It is cheap.
 Installation of the unshielded twisted pair is
easy.
 It can be used for high-speed LAN.
Disadvantage:
 This cable can only be used for shorter
distances because of attenuation.

12. Shielded Twisted Pair
 A shielded twisted pair is a cable that
contains the mesh surrounding the wire
that allows the higher transmission rate.
7.12

13. Characteristics Of Shielded Twisted Pair:
 The cost of the shielded twisted pair cable is not
very high and not very low.
 An installation of STP is easy.
 It has higher capacity as compared to unshielded
twisted pair cable.
 It is shielded that provides the higher data
transmission rate.
Disadvantages
 It is more expensive as compared to UTP and
coaxial cable.
 Comparatively difficult to install and manufacture
 More expensive
 Bulky

14. 7.14
Figure 7.4 UTP and STP cables

15. Coaxial cable
 A coaxial cable is an electrical cable with a
copper conductor and an insulator shielding
around it and a braided metal mesh that
prevents signal interference and cross talk.
Coaxial cable is also known as coax.
7.15

16. 7.16
Figure 7.7 Coaxial cable

17. Applications of Coaxial cable
The coaxial cables are used in Ethernet LANs and also used
in MANs
 Television: Coaxial cable used for television would be
75 Ohm and RG-6 coaxial cable.
 Internet: Coaxial cables are also used for carrying
internet signals, RG-6 cables are used for this.
 CCTV: The coaxial cables are also used in CCTV systems
and both RG-59 AND RG-6 cables can be used.
 Video: The coaxial cables are also used in video
Transmission the RG-6 is used for better digital signals
and RG-59 for lossless transmission of video signals.
 HDTV: The HDTV uses RG-11 as it provides more space
for signals to transfer.
7.17

18. Advantages
 Coaxial cables support high bandwidth.
 It is easy to install coaxial cables.
 coaxial cables have better cut-through
resistance so they are more reliable and
durable.
 Less affected by noise or cross-talk or
electromagnetic inference.
 Coaxial cables support multiple channels
7.18

19. Disadvantages
 Coaxial cables are expensive.
 The coaxial cable must be grounded in
order to prevent any crosstalk.
 As a Coaxial cable has multiple layers it is
very bulky.
 There is a chance of breaking the coaxial
cable and attaching a “t-joint” by hackers,
this compromises the security of the data.
7.19

20. Fiber Optics
 A fibre optic cable is made of glass or
plastic and transmits signals in the
structure of light signals.
 It involves an inner glass core surrounded
by a glass cladding that reflects the light
into the core. Each fibre is encircled by a
plastic jacket.
7.20

21. 7.21

22. Main element of Fiber Optics:
 Core:
It is the central tube of very thin size made of optically
transparent dielectric medium and carries the light
transmitter to receiver
 Cladding:
It is outer optical material surrounding the core having
reflecting index lower than core and cladding helps to
keep the light within the core throughout the
phenomena of total internal reflection.
 Buffer Coating:
It is a plastic coating that protects the fiber made of
silicon rubber.
7.22

23. Fiber Optics
 Advantages:
 Increased capacity and bandwidth
 Lightweight
 Less signal attenuation
 Immunity to electromagnetic interference
 Resistance to corrosive materials
 Disadvantages:
 Difficult to install and maintain
 High cost
 Fragile
7.23

24. 7.24
7-2 UNGUIDED MEDIA: WIRELESS
It is also referred to as Wireless or Unbounded
transmission media. No physical medium is
required for the transmission of electromagnetic
signals.
Features:
The signal is broadcasted through air
Less Secure
Used for larger distances

25. 7.25
Figure 7.17 Electromagnetic spectrum for wireless communication

26. 7.26
Figure 7.19 Wireless transmission waves

27. Radio waves
 These are easy to generate and can
penetrate through buildings. The sending
and receiving antennas need not be
aligned. Frequency Range:3KHz – 1GHz.
AM and FM radios and cordless phones
use Radio waves for transmission.

7.27

28. 7.28

29. 7.29
Radio waves are used for multicast
communications, such as radio and
television, and paging systems. They
can penetrate through walls.
Highly regulated. Use omni directional
antennas
Note

30. Microwaves
 It is a line of sight transmission i.e. the
sending and receiving antennas need to
be properly aligned with each other. The
distance covered by the signal is directly
proportional to the height of the antenna.
Frequency Range:1GHz – 300GHz. These
are majorly used for mobile phone
communication and television distribution.
7.30

31. 7.31

32. Infrared

Infrared waves are used for very short
distance communication. They cannot
penetrate through obstacles. This
prevents interference between systems.
Frequency Range:300GHz – 400THz. It is
used in TV remotes, wireless mouse,
keyboard, printer, etc.
7.32

33. 7.33
Microwaves are used for unicast
communication such as cellular
telephones, satellite networks,
and wireless LANs.
Higher frequency ranges cannot
penetrate walls.
Use directional antennas - point to point
line of sight communications.
Note

34. 7.34
Infrared signals can be used for short-
range communication in a closed area
using line-of-sight propagation.
Note