Transmission Media in Computer Networks

Last Updated : 03 Oct, 2025

Transmission media is the physical medium through which data is transmitted from one device to another within a network. These media can be wired or wireless. The choice of medium depends on factors like distance, speed, and interference. In this article, we will discuss the transmission media and it's types in detail.

Transmission Media is broadly classified into the following types:

Types-of-Transmission-Media — Types of Transmission Media

1. Guided Media

Guided Media 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. There are 3 major types of Guided Media: Twisted Pair, Coaxial and Optical Fiber Cables

Features:

High Speed
Secure
Used for comparatively shorter distances

1.1 Twisted Pair Cable

It consists of 2 separately insulated conductor wires twisted about each other. Generally, several such pairs are bundled together in a protective sheath. They are the most widely used Transmission Media. Twisted Pair is of two types:

(a) Unshielded Twisted Pair (UTP): 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.

unshielded_twisted_pair — Unshielded Twisted Pair

Advantages:

Least expensive
Easy to install
High-speed capacity

Disadvantages:

Lower capacity and performance in comparison to STP
Short distance transmission due to attenuation

(b) Shielded Twisted Pair (STP): Shielded Twisted Pair (STP) cable consists of a special jacket (a copper braid covering or a foil shield) to block external interference. It is used in fast data rate Ethernet and in voice and data channels of telephone lines.

shielded_twisted_pair — Shielded Twisted Pair

Advantages:

Better performance at a higher data rate in comparison to UTP
Eliminates crosstalk
Comparatively faster

Disadvantages:

Comparatively difficult to install and manufacture
More expensive
Bulky

1.2 Coaxial Cable

Coaxial cable has an outer plastic covering containing an insulation layer made of PVC or Teflon and 2 parallel conductors each having a separate insulated protection cover. The coaxial cable transmits information in two modes: Baseband mode(dedicated cable bandwidth) and Broadband mode(cable bandwidth is split into separate ranges). Cable TVs and analog television networks widely use Coaxial cables.

Coaxial Cable

Advantages:

Coaxial cables has high bandwidth .
It is easy to install.
Coaxial cables are more reliable and durable.
Less affected by noise or cross-talk or electromagnetic inference.
Coaxial cables support multiple channels

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.

1.3 Optical Fiber Cable

Optical Fibre Cable uses the concept of total internal reflection of light through a core made up of glass. The core is surrounded by a less dense glass or plastic covering called the coating. It is used for the transmission of large volumes of data. The cable can be unidirectional or bidirectional. The WDM (Wavelength Division Multiplexer) supports two modes, namely unidirectional and bidirectional mode.

optical_fibre_cable — Optical Fibre Cable

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

Applications:

Medical Purpose: Used in several types of medical instruments.
Defence Purpose: Used in transmission of data in aerospace.
For Communication: This is largely used in formation of internet cables.
Industrial Purpose: Used for lighting purposes and safety measures in designing the interior and exterior of automobiles.

1.4 Stripline

Stripline is a transverse electromagnetic (TEM) transmission line medium invented by Robert M. Barrett of the Air Force Cambridge Research Centre in the 1950s. Stripline is the earliest form of the planar transmission line. It uses a conducting material to transmit high-frequency waves it is also called a waveguide. This conducting material is sandwiched between two layers of the ground plane which are usually shorted to provide EMI immunity.

1.5 Microstripline

A microstripline is a type of transmission media used to carry high-frequency signals, commonly found in microwave and radio frequency circuits. It consists of a flat, narrow conducting strip (usually made of metal) placed on top of a dielectric material (an insulating layer), with a metal ground plane on the other side.

2. Unguided Media

It is also referred to as Wireless or Unbounded transmission media . No physical medium is required for the transmission of electromagnetic signals. There are 3 types of Signals transmitted through unguided media: Radio wave, Microwave and Infrared Wave.

Features:

The signal is broadcasted through air
Less Secure
Used for larger distances

2.1 Radio Waves

Radio waves are easy to generate and can penetrate through buildings. The sending and receiving antennas need not be aligned. Frequency Range: \text{3KHz - 1GHz}. AM and FM radios and cordless phones use Radio waves for transmission.

Types of Radio Waves:

Short Wave: AM Radio
VHF (Very High Frequency): FM Radio/TV
UHF (Ultra High Frequency): TV

Radio Wave Components:

Transmitter: Responsible for encoding the signal.
Receiver: Responsible for decoding the signal.

radiowaves — Radiowaves

2.2 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. Micro waves are majorly used for mobile phone communication and television distribution.

Advantages:

Cheaper than using cables
Freedom from land acquisition
Ease of communication in difficult terrains
Communication over oceans

Disadvantages:

Insecure communication.
Out of phase signal.
Susceptible to weather conditions.
Bandwidth is limited.
High cost of design, implementation, and maintenance.

microwave_transmission — Microwave Transmission

2.3 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.

infrared — Infrared

Difference Between Radio Waves, Micro Waves, and Infrared Waves

Basis	Radiowave	Microwave	Infrared wave
Direction	These are omni-directional in nature.	These are unidirectional in nature.	These are unidirectional in nature.
Penetration	At low frequency, they can penetrate through solid objects and walls but high frequency they bounce off the obstacle.	At low frequency, they can penetrate through solid objects and walls. at high frequency, they cannot penetrate.	They cannot penetrate through any solid object and walls.
Frequency range	Frequency range: 3 KHz to 1GHz.	Frequency range: 1 GHz to 300 GHz.	Frequency range: 300 GHz to 400 GHz.
Security	These offers poor security.	These offers medium security.	These offers high security.
Attenuation	Attenuation is high.	Attenuation is variable.	Attenuation is low.
Government License	Some frequencies in the radio-waves require government license to use these.	Some frequencies in the microwaves require government license to use these.	There is no need of government license to use these waves.
Usage Cost	Setup and usage Cost is moderate.	Setup and usage Cost is high.	Usage Cost is very less.
Communication	These are used in long distance communication.	These are used in long distance communication.	These are not used in long distance communication.

Causes of Transmission Impairment

Transmission impairment refers to the loss or distortion of signals during data transmission, leading to errors or reduced quality in communication. Common causes include signal distortion, attenuation, and noise all of which can affect the clarity and reliability of transmitted data.

impairment_causes — Transmission Impairment

Attenuation: Loss of signal strength as it travels over distance due to resistance of the medium. Amplifiers are used to restore the signal.
Distortion: Change in the shape of a signal, usually in composite signals with different frequencies. Since each frequency travels at a different speed, they reach the receiver at different times, causing phase shifts and distortion.
Noise: Unwanted signals that mix with the original signal, potentially corrupting it. Common types include induced noise, crosstalk, thermal noise, and impulse noise.

Factors Considered for Designing the Transmission Media

Bandwidth: Assuming all other conditions remain constant, the greater a medium's bandwidth, the faster a signal's data transmission rate.
Transmission Impairment : Transmission Impairment occurs when the received signal differs from the transmitted signal. Signal quality will be impacted as a result of transmission impairment.
Interference: Interference is defined as the process of disturbing a signal as it travels over a communication media with the addition of an undesired signal.

Applications of Transmission Media in Computer Networks

Transmission Media	Application
Unshielded Twisted Pair (UTP)	Local Area Networks (LAN), telephones
Shielded Twisted Pair (STP)	Industrial networks, environments with high interference
Optical Fiber Cable	Long-distance communication, internet backbones
Coaxial Cable	Cable TV, broadband internet, CCTV
Stripline	Printed Circuit Boards (PCBs), microwave circuits
Microstripline	Antennas, satellite communication, RF circuits
Radio	Wireless communication, AM/FM radio, mobile phones
Infrared	Remote controls, short-range communication
Microwave	Satellite communication, radar, long-distance links

Transmission Media in Computer Networks

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