Transmission Media

1. Wired Media and Connector
1.1. Coaxial cables
1.2. Twisted Pair Cables
1.3. Optical Fiber Cables
1.4. Serial Cables
2. Properties of Cables
3. Cable Connections
4. Wireless Media
4.1. Radiowaves
4.2. Microwaves
4.3. Infrared waves

Wired Media And Connectors

1. Co axial Cables
Coaxial cable or coax is a type of cable in which inner conductor is surrounded
by plastic jacket with a braided shield over it.
It include one physical channel that carries the signal and it is surrounded by
another concentric physical channel, both running along the same axis. That’s
why it known as “coaxial”.
Copper shield is covered by using PVC (Polyvinylchloride) or FEP
(Fluoroethylene Propylene) plastic.
For a High Frequency electrical signals it provide an interference-free
transmission path
Example: Thinnet,Thicknet,Television Cable

BNC connector
BNC stands for Bayonet Neil-Concelman or British Naval Connector.
It is a miniature quick connect/disconnect radio frequency connector with a
positive locking mechanism.
Mating is achieved with a quarter turns of the coupling nut.
BNC are lightweight and reliable connectors.
They are mostly made in 50 or 75 ohm version.
BNC connector are used with coaxial cable in radio, television and other
radio-frequency electronic equipment, test instruments, and video signals.

2. Twisted Pair cable
Twisted pair cables consist of two conductors, each with its own plastic
insulation and they are twisted together.
One wire is used to send signals to the destination and second wire is used as
ground reference.
They are twisted together to reduce crosstalk and EMI (electromagnetic
interference) from external source.At the receiver side there will be no signal
difference because unwanted signals are cancelled out.
It is used to transmit analog and digital signals and frequency signals ranges
from 100Hz to 5MHz
Types of Twisted Pair cables are UTP and STP.

Wired Media And Connectors

Unshielded twisted pair
The unshielded twisted pair cables don’t have an outer protection. These cables have covering jacket made of PVC or FEP plastics. This cable is used in computer network as ethernet cables. These Cables are less immune to external noise or interference

Shielded Twisted pair
The shielded twisted pair cables has a metal foil which cover the each pair of insulating conductor and have a outer layer cover made of PVC or FEP plastics. This cable are used in factories with large electronics equipments. These cables are more immune to external noise and interference due to presence of metallic shield.

Wired Media And Connectors

RJ 45 Connector
A Registered jack (RJ-45) is a standard type of physical network interface with
8 pin/8 position plug. ‘45’ refers to the number of interface standard.
It is used to connect computer onto Ethernet based LAN network
Two wiring schemes are used T568A and T568B to terminate the twisted-pair
cable onto the connector interface.
It is used with CAT5 and CAT6 cables.

Optical Fiber cables 
Optical fiber is a cylindrical non-conducting waveguide that transmit the light
along its axis.
It consist of core and cladding layer and refractive index of core is greater than
It transfer the light signal to a longer distance.
It follow the principle of total internal reflection (TIR) to transmit the light
through glass medium.
There are 2 types of optical fiber cable.

Single mode Optical fiber
This fiber has a small diameter of core and only one mode of light will travel through it.

It is used in long distance communication with high bandwidth links.

The diameter of core is 9 microns and cladding is of 125 microns.
Launching of light in this fiber is difficult.

Multimode optical fiber
This fiber can support multiple light rays to travel through it.

The diameter of core/ cladding is 50/125 and 62.5/125 microns.

This fiber contain large side of core as compared to single mode optical fiber.
Launching of light in this fiber is easy

It is further of two types

Step Index Fiber
In this fiber, the refractive index of the core is uniform and at the interface of core and cladding the refractive index change abruptly.
The size of core is large so it can support multiple modes. It is used in short distance communication.
The diameter of core/cladding is 200/380 microns

Graded Index optical fiber
In this fiber,the refractive index of
core is non-uniform i.e. the
refractive index decreases
gradually from the axis of the fibre
to its surface.
Light rays propagate in the form of
skew rays or helical rays.This fiber
reduce the modal dispersion .
It is also used for long distance
transmission of signals.

SC connector
SC stands for subscriber Connector or standard connector.
It has a 2.5mm Zirconia Ceramic ferrule and a push-pull latching
mechanism which is similar to common audio and video cables.It is used
for a fast and reliable connection in telecommunications networks.
Two fiber cables and two SC connectors (Dual SC) are used for
bidirectional transmission.
The SC connector are available in standard colours as blue (singlemode),
green (singlemode) and beige (multimode).
Example: CATV – Cable television,Fibre-To-The-Home ,LAN, MAN and
WAN network

ST connector
ST stands for Straight tip connector.This connector has a bayonet mount
and a long cylindrical 2.5 mm ceramic or polymer ferrule that hold the
Most ferrules are ceramic, but some are metal or plastic.
It is most popular connector for multimode networks
Usage of this connector decline from recent years because it cannot be
use in single mode fiber and FTTH applications as fiber is terminated with
an angled polish in this connector.

LC connector
LC stands for Lucent Connector and it is a miniaturized version of the
fiber-optic SC connector.
It look is similar as SC, but there is size difference LC connector has a size
1.25mm ferrule whereas SC connector is of 2.5mm.
It give the replacement to the SC connector in market but LC is more
costly than SC.
It is used in networking and FTTH applications.

MT-RJ Connector
MT-RJ stands for Mechanical Transfer Registered Jack.
MT-RJ is a fiber-optic Cable Connector in which two fibers are plug and
combine together with locating pins on the plug.
The MT-RJ looks similar to a RJ45 connector.
It is used for networking applications such as Ethernet network.
It’s size is small as compared to SC connector.
The MT-RJ Connector is low cost and small size

Serial Cables
‘Serial’ means the bits are send one by one through cables or fiber and it is
interpreted by the network card at the other end.
It use serial communication protocol to transfer the data between two device.
Type of serial cables are RS 232 and USB cables.

Wired Media And Connectors

RS 232
RS 232 is a standard for serial communication of data in the network.
This cable connect the DTE (Data Terminal Equipment) such as computer
and DCE (Data communication equipment) such as modem.
RS 232 standard defines the electrical characteristics , timing of signals,
the meaning of signals, and the physical size and pinout of connectors
It has low transmission speed, large voltage swing and large standard

USB Cables
Universal Serial Bus is an industry standard that defines the
communication protocols
It is used for connection, communication, and power supply between
computers and electronic devices.
RS 232 cables are replaced by USB in many devices
USB cables are available in many version according to their use.
These cables has fast transmission speed and use low power supply.

Properties of Cables
1. Noise Immunity: Noise is a random fluctuation in an electrical signal. Noise
generated in cables affect the information or data signals.coaxial cables
are adversely affected by the noise created by external sources. Fiber
cables are more immune to noise effects. So, cable with more immunity to
noise should be design to reduce the signal degradations.
2. Speed of Transmission: Each cables have there own speed of transmitting
signals like coaxial cables transmit data at lower rate whereas fiber cable
transmit signals at faster rates. So according to the demand of network,
desired cables must be installed.
3. Frequency: Each cable has a specified maximum frequency that define
how much transmission bandwidth it can handle. CAT 5 cables are tested
at 100 MHz maximum frequency and transmit signal at 1gbps in short
distances but CAT6 is tested at 250 MHz frequency and it handle data at
1gbps in long distance communication. So according to the demand of
bandwidth in network desired cables should installed.
4. Distance of transmission: Each cable has different speed of transmission it
means these cables can transmit signals in some define range or distance.
Some cables are installed for long distance communication and some are
used for short distance communication because as the signal travel it start
degrading due to loses.

Cable Connections

1. Straight through cables
It is used to do the straight connection between the devices such as
connection between host and clients
These cables have the pin assignments on each end of the cable.
Like Pin 1 connector A connect to Pin 1 on connector B, Pin 2 to Pin 2 and
so on

2. Crossover cables
Crossover cables are same as Straight-Through cables but with little
difference that TX and RX wires are crossed it means they are at opposite
positions on both end of the cable.
In this type of connection , 586B standard is used
Example Pin 1 on connector A goes to Pin 2 on connector B. Pin 2 on
connector A goes to Pin 1 on connector B etc.
This is used to connect two hosts directly such as connecting a computer
directly to another computer, connecting a switch directly to another
switch, or connecting a router to a router.

3. Rollover Cables
Rollover cables have opposite pin assignments on each end of the cable .
Like Pin 1 of connector A will connected to Pin 8 of connector B.Pin 2 of
connector A will be connected to Pin 7 of connector B and so on.
They are not used to carry data but used to create an connection between
the device.

4. Hardware Loopback
Hardware loopback connection are used to check the capability of a
device that it can transmit and receive the signal efficiently in the network
This is a process of routing a signals or data back to their source without
any modification.
This is used to test the transmission or transportation infrastructure of a
network devices.

Wireless Media

Radio waves are a part of electromagnetic radiation
It wavelengths in the electromagnetic spectrum is longer than infrared light.
It frequency ranges from 300 GHz to 3 kHz,
It is used for mobile radio communication, broadcasting, navigation systems,
satellites communication, computer networks and various other applications.
These waves are generated by radio transmitters and alway received by radio

Omnidirectional antennas
Omnidirectional antenna are type of antenna which radiate radio waves in
all directions.
It is used in RF wireless devices such as cellular mobile phone and
wireless routers.
This antenna radiate equally in all directions.

Microwaves are the type of electromagnetic radiation
It wavelengths ranges from 1m to one mm.
It frequency ranges between 300 MHz and 300 GHz.
It is used by mobile phone communication, satellite communication, fixed
traffic speed cameras and for radar, which is used by aircraft, ships and
weather forecasters.

Unidirectional Antenna
Unidirectional propagation antenna is an antenna that’s propagation
pattern is in one direction.
This antennas are good for communicating with someone when you know
there location.
Example: Radar antennas, Yagi-Uda antennas, Satellite dish

Infrared waves
Infrared (IR) is an invisible radiant energy signal present in electromagnetic
radiation its frequency ranges from 430 THz to 300 GHz
It is used in industrial, scientific, and medical applications.
It is widely used in military applications like target acquisition, surveillance,
night vision, and tracking.


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