The document provides an overview of various types of transmission media, including guided and unguided media, elaborating on twisted-pair cables, coaxial cables, and fiber optics with their respective advantages and disadvantages. It explains the functions and characteristics of each type of media, alongside connector types and classification standards. Additionally, it covers unguided media, including radio waves, microwaves, and infrared communication methods.

1. Transmission Media
Dr R Jegadeesan Prof-CSE
Jyothishmathi Institute of Technology and Science, karimnagar

2. ◼ Transmission media is defined as any thing that
carries information from a source to destination
◼ For example transmission media for two people
having a dinner conversation is the air.
◼ For a written message , the transmission medium
might be a mail carrier, a truck or an airplane

3. The position of Transmission medium in relation to the physical layer

4. Classification of transmission media

5. GUIDED MEDIA

6. ➢Guided media, in this type of media , a physical path
is established between source and destination .
➢The signal which is in the form of electromagnetic
waves utilizes the path for transmission
Guided media is of 3 types
➢ Twisted-Pair Cable
➢ Coaxial Cable
➢ Fiber - Optic Cable

7. Twisted-pair cable
◼ A twisted pair consists of two conductors normally
copper are twisted around one another each with its
own plastic so as to reduce disturbance caused by
electromagnetic waves

9. ➢ One of the wires are used to carry signals to
the receiver and other is used as a ground
reference. The receiver uses the difference
between the two.
➢ In addition to the signal sent by the sender on
one of the wires, interference (noise) and cross
talk may effect both wires and create unwanted
signals.

10. ➢ If the two wires are parallel, the effect of
these unwanted signals is not same in both
wires.
➢ Because they are at different locations
relative to noise or cross talk sources
➢ e.g. one is closer and one is farther
➢ This results in a difference at the receiver.

11. ➢ By twisting the pairs, a balance is maintained.
➢ For example, suppose in one twist, one wire is closer
to the noise source and the other is farther; in the
next twist, the reverse is true.
➢ Twisting makes both the wires are equally affected
by external influences (noise or cross talk)
◼ This means that the receiver which calculates the
difference between the two, receives no unwanted
signals. The unwanted signals are mostly cancelled
out

12. There are two types of twisted pair cables
➢ Unshielded twisted-pair (UTP)
➢ Shielded twisted-pair (STP)

14. UTP and STP cables

15. Unshielded twisted-pair (UTP)
➢ In UTP there is no shielding around the twisted pair.
➢ UTP cables are used in telephone companies, computer
networking, Ethernet systems and also in token ring.
➢ The cable has four pairs of wires inside the jacket.
➢ Each pair is twisted with a different number of twists per
inch to help eliminate interference from adjacent pairs and
other electrical devices.

16. Categories of UTP
➢ The Electronic Industries Association (EIA)
has developed standards to classify unshielded
twisted-pair cable into seven categories.
➢ Categories are determined by cable quality,
with 1 as the lowest and 7 as the highest

17. ➢ Category 1 :Voice Only data to < 0.1 Mbps (Telephone Wire)
➢ Category 2 : Data to 4 Mbps (Local Talk)
➢ Category 3 :Data to 10 Mbps (Ethernet)
➢ Category 4 : Data to 20 Mbps (16 Mbps Token Ring)
➢ Category 5 : Data to 100 Mbps (Fast Ethernet)
➢ Category 6 : Data to 200 Mbps (Fast Ethernet)
➢ Category 7 : Data to 600 Mbps (Fast Ethernet)

18. ◼ One difference between the different
categories of UTP is the tightness of
the twisting of the copper pairs.
◼ The tighter the twisting, the higher
the supported transmission rate and
the greater the cost per foot.

19. UTP connector RJ 45( Registered Jack 45)
The RJ 45 is a keyed connector meaning the connector can be
inserted in one way only.

20. Shielded Twisted-Pair Cable( STP)
◼ In STP there is a tough protective shield of metallic
foil or braided mesh covered over each pair of
copper wire that is used to reduce electromagnetic
interference that occurs during transmission

21. ◼ STP cabling often is used in Ethernet
networks, especially fast data rate Ethernets,
Telephone networks
◼ The advantage of STP is it reduces external
interferences.
◼ STP is expensive compared to UTP

22. Co-axial cable
➢ Coaxial cable (or coax) carries signals of
higher frequency ranges than those in twisted
pair cable
➢ Co axial cable is different from that of twisted
pair cable.
➢ Co axial cable comprise of two conductors.

23. ➢ Inner conductor( core conductor) enclosed
in an insulating sheath.
➢ Outer conductor of metal foil, braid, or a
combination of the two.
➢ This outer conductor is also enclosed in an
insulating sheath, and the whole cable is
protected by a plastic cover

24. Coaxial cable

26. Usage of co axial cables
◼ Coaxial cables can be used both for long
distance and short distance transmission.
◼ Coaxial cable is sometimes used by telephone
companies from their central office to the
telephone poles near users.
◼ Coaxial cables are used for connecting
television networks

27. Categories of coaxial cables
▪ Coaxial cables are categorized by their radio government
(RG) ratings.
▪ Each RG number denotes a unique set of physical
specifications, including
➢ the wire gauge of the inner conductor,
➢ the thickness and type of the inner insulator,
➢ the construction of the shield,
➢ the size and type of the outer casing

29. RG 59

30. RG 58

31. RG 11

32. Coaxial Cable Connectors
◼ To connect coaxial cable to devices, we need
coaxial connectors.
◼ The most common type of connector used
today is the Bayone -Neill- Concelman
(BNC), connector

33. BNC connectors
There three popular types of these
connectors:
➢ BNC connector
➢ BNC T connector
➢ BNC terminator

35. ◼ The BNC connector is used to connect the
end of the cable to a device, such as a
TV set.

36. ◼ The BNC T connector is used in Ethernet
networks to branch out to a connection to a
computer or other device.

37. ➢ The BNC terminator is used at the end of
the cable to prevent the reflection of the
signal.

38. Fiber optics cables
➢ A fiber-optic cable is made of glass or plastic
and transmits signals in the form of light.
➢ Fiber optic cable consists of three layers.
➢ Core
➢ Cladding
➢ Jacket

39. ➢ Core - Thin glass center of the fiber where the
light travels.
➢ Cladding - Outer optical material surrounding
the core that reflects the light back into the
core.
➢ Jacket-optical fibers are arranged in bundles
in optical cables. The bundles are protected by
the cable's outer covering, called a jacket.

40. Optical fiber

42. Advantages of optical fiber
➢ Wider bandwidth( GHz)
➢ Immunity ( protection)
➢ Reduce transmission loss
➢ Improved security
➢ Durability (works longer time)
➢ Reliable

43. Disadvantages of optical fiber
➢ Cost
➢ Losses through bending
➢ Specialized tools equipment and training
➢ Less strength

44. Fiber optics support two modes of Propagation

45. Multimode
➢ It allows multiple beams of light. This is more
suitable for short distance transmission.
➢ There are two types of multi modes.
➢ Step index multimode
➢ Graded-index multimode

46. Step index multimode
➢ It consists of large core through which the beam of light tend
to bounce and reflect back to cladding and inside core.
➢ Because of this reflection some light ray takes larger path or
shorter path due to which the light ray arrives at different times
at the receiver

47. Graded-index multimode
◼ This mode allows the beam of light to bent back into the core
path .
◼ The word index here refers to the index of refraction.
◼ the index of refraction is related to density (thickness).
◼ Density is highest at the center of the core and decreases
gradually to its lowest at the edge

48. Single mode
➢ It uses single beam of light.
➢ The light ray passes through the core with
fewer reflection due to which it gives better
performance.
➢ They are preferred for long distance

50. Fiber construction

51. Fiber optics connectors
➢ There are three types of connectors for fiber-
optic cables
➢ Subscriber channel (SC) connector
➢ Straight tip (ST) connector
➢ Mechanical Transfer Registered Jack
(MTRJ)

52. Fiber-optic cable connectors

54. UNGUIDED MEDIA
(WIRELESS)

55. ➢Unguided media transport electromagnetic waves
without using a physical path.
➢This type of communication is often referred to as
wireless communication which does not guide the
waves but provide methods or ways for transmitting
them.
➢Waves are propogated through air , vacuum and
seawater

56. Electromagnetic spectrum is used for making
transmission possible for unguided media
ranging from 3 KHz to 900THz

57. Propagation methods
◼ Unguided signals can travel from source to
destination in several ways
➢ Ground propagation
➢ Sky propagation
➢ Line-of-sight propagation

58. Ground propagation
➢ In this radio waves travel through lowest portion
of the atmosphere, hugging earth.
➢ The low frequency signals travel in all directions
from the transmitting antenna and follow the
curvature of the planet.
➢ Distance depends on the amount of power in the
signal: The greater the power, the greater the
distance.

60. Sky propagation
➢ In sky propagation, higher-frequency radio
waves radiate upward (uplink frequency) into
the ionosphere where they are reflected back
(downlink frequency) to earth.
➢ This type of transmission allows for greater
distances with lower output power.

62. Line-of-sight propagation
◼ In line-or-sight propagation, very high-
frequency signals are transmitted in straight
lines directly from antenna to antenna
◼ Antennas must be directional, facing each
other and either tall enough or close enough
together not to be affected by the curvature of
the earth.

64. Propagation methods

65. Wireless transmission waves

66. Radio waves
◼ Electromagnetic waves ranging in frequencies between 3KHz
and 1GHz are normally called radio waves
◼ Radio waves, for the most part, are Omni directional.
◼ When an antenna transmits radio waves, they are propagated
in all directions. A sending antenna sends waves that can
be received by any receiving antenna.
◼ Radio waves, particularly those waves that propagate in the
sky mode, can travel long distances.

67. ◼ The radio wave band is relatively narrow, just
under 1 GHz, compared to the microwave
band. When this band is divided into sub
bands, the sub bands are also narrow, leading
to a low data rate for communications
◼ Radio waves are used for multicast
communications, such as radio and
television, and paging systems. They can
penetrate through walls.

68. Omni directional antenna

70. Microwaves
◼ Electromagnetic waves having frequencies between 1 and
300 GHz are called microwaves.
◼ Microwaves are unidirectional.
◼ When an antenna transmits microwave waves, they can be
narrowly focused. This means that the sending and receiving
antennas need to be aligned

71. Characteristics of microwave propagation
◼ Microwave propagation is line-of-sight. The towers
with the mounted antennas need to be in direct sight
of each other, towers that are far apart need to be
very tall.
◼ Repeaters are often needed for long distance
communication.
◼ The microwave band is relatively wide, almost 299
GHz. Therefore high data rate is possible

72. Unidirectional Antenna
◼ Microwaves need unidirectional antennas that send
out signals in one direction.
◼ Two types of antennas are used for microwave
communications:
➢ Parabolic dish antenna
➢ Horn antenna

73. Parabolic dish antenna
◼ A parabolic dish antenna is based on the geometry
of a parabola.
◼ Every line parallel to the line of symmetry (line of
sight) reflects off the curve at angles such that all
the lines intersect in a common point called the
focus.
◼ The parabolic dish works as a catching a wide range
of waves and directing them to a common point.

75. Horn antenna
◼ A horn antenna looks like a gigantic scoop.
◼ Outgoing transmissions are broadcast up a stem
(resembling a handle) and deflected outward in a
series of narrow parallel beams by the curved head.
◼ Received transmissions are collected by the scooped
shape of the horn, in a manner similar to the
parabolic dish, and are deflected down into the stem.

77. Unidirectional antennas

78. ◼ Microwaves are used for unicast
communication such as cellular
telephones, satellite networks, and
wireless LANs.

79. Infrared
◼ Infrared waves, with frequencies from 300
GHz to 400 THz can be used for short-range
communication.
◼ Infrared waves, having high frequencies,
cannot penetrate walls. This advantageous
characteristic prevents interference between
one system and another.
◼ Infrared signals are useless for long-range
communication

80. ◼ we cannot use infrared waves outside a
building because the sun's rays contain
infrared waves that can interfere with the
communication.
◼ Infrared signals can be used for short-range
communication in a closed area using line-
of-sight propagation.

82. Thank you