Types of Transmission Media In Computer Network

Types of Transmission Media In Computer Network

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Jaya Sharma
Assistant Manager - Content
Updated on Jan 23, 2024 15:29 IST

There are two type of transmission media including guided media and unguided media. In guided transmission media, waves are guided along solid mediym such as transmission line. Transmission and reception in unguided transmission media are achieved through antenna. 

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In this article, we will be discussing what is transmission media and its types in detail. We will try to understand the functionalities and advantages of this communication channel.

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What is Transmission Media in Computer Network?

Transmission media is a communication channel that transmits information from the source/transmitter to the receiver. It is a physical path for data transfer through electromagnetic signals. Information is carried over in the form of bits through LAN. It can mediate the propagation of signals for telecommunication. Signals are imposed on a wave that is suitable for the chosen medium. These media lie underneath the physical layer that regulates them. While designing a transmission, it is important to keep the following pointers in mind:

  • The bandwidth should be greater since it will result in a higher data transmission rate of a signal.
  • Noise should be less. Otherwise, data signal can be distorted.

What are the Types of Transmission Media in Computer Networks?

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If you are wondering how many types of transmission media are there, then do take a look at this section. Broadly, there are two types of transmission media in computer networks including guided and unguided media. These two types of transmission medium in computer networks have further subtypes. Let us discuss these in detail.

1. Guided Transmission Media

Guided media are also known as wired or bounded media. These media consist of wires through which the data is transferred. Guided media is a physical link between transmitter and recipient devices. Signals are directed in a narrow pathway using physical links. These media types are used for shorter distances since physical limitation limits the signal that flows through these transmission media.

1.1 Twisted Pair Cable

In this type of transmission media, two insulated conductors of a single circuit are twisted together to improve electromagnetic compatibility. These are the most widely used transmission medium cables. These are packed together in protective sheaths. They reduce electromagnetic radiation from pairs and crosstalk between the neighbouring pair. Overall, it improves the rejection of external electromagnetic interference. These are further subdivided into unshielded and shielded twisted pair cables. 

1.1.1 Unshielded Twisted Pair Cable(UTP): These consist of two insulated copper wires that are coiled around one another. These types of transmission media block interference without depending on any physical shield. The unshielded twisted pair are very affordable and are simple to set up. These provide a high-speed link. 

1.1.2 Shielded Twisted Pair (STP): This twisted cable consisted of a foil shield to block external interference. The insulation within these types of twisted cable allow greater data transmission rate. These are used in fast-data-rate Ethernet and in data and voice channels of telephone lines.  

1. 2 Optical Fibre Cable

Also known as fiber optic cable, these are thin strands of glass that guide light along their length. These contain multiple optical fibers and are very often used for long-distance communications. Compared to other materials, these cables can carry huge amounts of data and run for miles without using signal repeaters. Due to lesser requirements, they have less maintenance costs and it improves the reliability of the communication system. These can be unidirectional as well as bidirectional in nature. 

1.3 Coaxial cable

These guided transmission media contain an insulation layer that transmits information in baseband mode and broadband mode. Coaxial cables are made of PVC/Teflon and two parallel conductors that are separately insulated. Such cables carry high frequency electrical signals without any big loss. The dimension of cable and connectors are controlled to give them constant conductor spacing for efficient functioning as a transmission line.

1.3.1 Hardline Coaxial Cable: These are used for high signal strength applications including long-distance telephone lines. These look like any regular coaxial cable but these are 1.75" thick. This type of cable has the capability to carry hundreds of channels of cable tv. Such cables have sufficient interent capacity for medium sized office building.

1.3.2 RG-6 Coaxial Cable: This is mainly used for cable and satellite signal transmission for the purpose of residential and commercial installation. These are thin and are easily bendable for wall or ceiling installation. Such cables are preferred for relaying cable television signals.

1.3.3 Triaxial Cable: Also known as triax, these are the electrical cable that come with an add on layer of insylation and second conducting sheat. These cables provide greater bandwidth as well as rejection of interference as compared to coax. However, triaxal cable are expensive type of transmission media.

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1.4 Stripline 

This is a  transverse electromagnetic (TEM) transmission media that is built on the inner layers of multi-layer printed circuit boards. These are used in high or low-level RF signals that require isolation from surrounding circuitry. It is a type of printed circuit transmission line in which a signal trace is sandwiched between the upper and lower ground place. Stripline minimizes emissions electromagnetic radiation is completely enclosed within homogeneous dielectric. Along with the reduced emissions, it also shields against incoming spurious signals. 

1.5 Microstripline

While Microstripline is simiar to stripline, it is not sandwiched and are present above the ground plane. These can be fabricated with any technology where the conductor is separated from the ground plane by a dielectric layer called subtrated. These transmission media convert microwave frequency signals. Microstrip is also used for building microwave components such as couplers, filters, power dividers, antennas, etc. In comparison with the traditional waveguide technology, it is less expensive.

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2. Unguided Transmission Media

Also known as unbounded or wireless media, they help in transmitting electromagnetic signals without using a physical medium. Here, air is the medium. There is no physical connectivity between transmitter and receiver. These types of transmission media are used for longer distances however they are less secure than guided media. There are three main types of wireless transmission media. 

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2.1  Radio Waves

Radio waves are transmitted in every direction throughout free space. Since these are omnidirectional, sent waves can be received by any antenna. These waves are useful when the data is to multicasted from one sender to multiple receivers. Radio waves can cover large areas and even penetrate obstacles such as buildings and walls. The frequency of these waves ranges between 3 kHz to 1GHz. Due to its omnidirectional nature, issues such as interference might arise when another signal with the same bandwidth or frequency is sent.  

2.2 Infrared

These waves are useful for only very short distance communication. Unlike radio waves, they do not have the ability to penetrate barriers. Their range varies between 300GHz – 400THz. Since they have larger bandwidth, the data rate is very high for infrared waves. These have less interference and are more secure. 

2.3 Microwaves

For these waves, it is important for the transmitter and receiver antenna to be aligned. This is why it is known as line-of-sight transmission. Due to this, they are suitable for shorter distances. They comprise of electromagnetic waves with frequencies ranging between 1-400 GHz. Microwaves provide bandwidth between the range of 1 to 10 Mbps. Distance covered by the signal is proportional to the height of the antenna. For travelling to longer distances, the height of the tower should be increased. These are further sub categorized as terrestrial and satellite type microwave transmission. 

2.3.1 Terrestrial type microwave transmission: In this type, high directional antennas are used for line of sight propagation paths that use frequency between 4-12 GHz. These are parabolic antennas having diameters that range from 12 inches to feet depending on their spacing. 

2.3.2 Satellite type microwave transmission: Signals are transmitted to those spaces where satellites are positioned and they retransmit the signal to appropriate locations. Since they only receive and retransmit the signal, they act as repeaters. It is a much more flexible and reliable method of communication in comparison with cables and fiber systems. 

 

Pros and Cons of Transmission Media in Computer Networks

The following table summarises the advantages and disadvantages of transmission media:

Type Advantages Disadvantages
Unshielded Twisted Pair  Less expensive,
Easy to install,
High speed
Attenuation leads to short-distance communication,
Susceptible to external interference
Shielded Twisted Pair Reduced crosstalk,
Faster than UTP
Bulky and expensive,
Difficult to install
Optical Fibre Cable Increased bandwidth,
Immunity to interference
High-cost, Fragile
Coaxial Cable High bandwidth,
Noise immunity
Complete disruption due to single cable failure
Stripline Better isolation,
Less loss of radiation
Complex troubleshooting, 
Expensive
Microstripline Easy interconnection and adjustments,
Major fabrication advantage over stripline due to its open structure
Only for a short distance
Radio Easy to generate, 
Can penetrate obstacles
More interference
Infrared Less interference Cannot penetrate obstacles

Considerable Factors While Designing Transmission Media

While designing transmission medium in computer networks, it is important to consider the following factors:

  • Greater bandwidth of the transmission medium allows higher data transmission rate of signal.
  • Due to transmission impairment, the received signal may get destroyed since it does not seem identical to the transmitted signal.

Applications of Transmission Media in Computer Networks

Type Uses
Unshielded Twisted Pair  Telephonic applications
Shielded Twisted Pair Fast data rate ethernet
Optical Fibre Cable For transferring large volume of data
Coaxial Cable Cable TVs,  Analog TV
Stripline Solid-state microwave systems
Microstripline Solid-state microwave systems
Radio Cordless phones, AM/FM radios
Infrared Wireless mouse, printers, keyboards
Microwave Mobile phones, televisions

Conclusion 

We hope that you have now learned about the types of transmission in computer networks. Based on the data rate and distance between the transmitter and receiver, a suitable transmission media can be selected. One can also select the transmission type based on whether they require a physical medium or not.

FAQs

How does coaxial cable differ from twisted pair cable?

Coaxial cable consists of a central conductor surrounded by an insulating layer, a metallic shield, and an outer insulating layer. It provides better shielding against interference and offers higher bandwidth and longer transmission distances compared to twisted pair cables.

What are the main advantages of wireless transmission?

Wireless transmission offers mobility, flexibility, and convenience, allowing users to connect to networks without the need for physical cables. It enables easy access to information and communication from various devices within the network coverage area.

What are the disadvantages of wireless transmission?

Wireless transmission is susceptible to interference from other wireless devices and physical obstacles such as walls or buildings. It may also have limited bandwidth and slower speeds compared to wired transmission media. Additionally, wireless networks may require additional security measures to protect against unauthorized access.

What makes fiber optic cables suitable for long-distance communication?

Fiber optic cables use light signals to transmit data, which allows them to maintain signal integrity over long distances. They have low signal attenuation, meaning the signals can travel longer distances without significant degradation compared to electrical signals used in other media.

Can different types of transmission media be used together in a network?

Yes, it is possible to use different types of transmission media in a network. This is known as a hybrid network, where each type of media is utilized based on its advantages and requirements. For example, fiber optic cables can be used for long-distance backbone connections, while twisted pair or coaxial cables can be used for shorter distance connections within buildings.

About the Author
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Jaya Sharma
Assistant Manager - Content

Jaya is a writer with an experience of over 5 years in content creation and marketing. Her writing style is versatile since she likes to write as per the requirement of the domain. She has worked on Technology, Fina... Read Full Bio