Difference Between Guided And Unguided Media

What Is Guided Media?

Guided media also referred to as Wired or bounded transmission media, are those that provide a channel from one device to another; they include twisted-pair cable, coaxial cable and fibre-optic cable. A signal traveling along any of these media is directed and contained by the physical limits of the media.

Major Types of Guided Media 

(i) Twisted Pair Cable –
It consists of 2 separately insulated conductor wires wound about each other. Generally, several such pairs are bundled together in a protective sheath. They are the most widely used Transmission Media.

(ii) Coaxial Cable –
It has an outer plastic covering containing 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. 

(iii) Optical Fibre Cable – 
It uses the concept of reflection of light through a core made up of glass or plastic. The core is surrounded by a less dense glass or plastic covering called the cladding. 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.

(iv) 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.

What You Need To Know About Guided Media

• The signal energy propagates through wires in guided media.
• It transmits data in the form of an electrical or optical signal.
• It is also referred to as wired communication or bounded transmission.
• Guided media is used for point to point communication.
• Discrete network topologies are formed by the guided media.
• Transmission speed is generally faster.
• Signals are in the form of voltage, current or photons in the guided media.
•  By adding more wires, the transmission capacity can be increased in guided media.  
• It provides better security during transmission.
• It has a low effect on human health when compared to unguided media.
• It is generally flexible and low-cost media.
• Examples of guided media include: twisted pair wires, coaxial cables, optical fibre cables etc.

What Is Unguided Media?

Unguided media is one that does not use the physical medium to transmit information and from one end to another end. Unlike the guided transmission media, the unguided media utilize air as a transmission media instead of wire or cable and thus it is also referred to as wireless or unbound transmission media. There are three ways in which unguided signals can transmit that is, sky propagation, ground propagation and line of sight propagation.

In ground propagation, the signals are transmitted in the lowest layer of the atmosphere and can be sent in all directions using the antenna as a transmitting device. The signals are transmitted as the frequency is lower for these signals.

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

In line of sight propagation, very high-frequency signals are transmitted in straight lines directly from antenna to antenna.

Wireless transmission can be categorized into three broad groups:

• Radio waves
• Micro waves
• Infrared waves

(i) Radiowaves – 
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 Radiowaves for transmission. Further Categorized as Terrestrial and Satellite. 

(ii) 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. 

(iii) 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.

What You Need To Know About Unguided Media

• The signal energy propagates through air in unguided media.
• It transmits data in the form of electromagnetic signals (radio signs).
• It is also referred to as wireless communication or unbounded transmission media.  
• Unguided media is generally suited for radio broadcasting in all directions.
• Continuous network topologies are formed by unguided media.  
• Transmission speed is generally slow.
• Signals are in the form of electromagnetic waves in unguided media.
• It is not possible to obtain additional capacity in unguided media.
• The security is weak during transmission.
• It has more effect on human health as compared to guided media.
• It is generally complex and high-cost media.
• Examples of unguided media are satellite communication, microwave, terrestrial microwave, light wave, radio wave and infrared light.

Difference Between Guided And Unguided Media In Tabular Form

Advantages And Disadvantages of Guided Media

Advantages

• Transmission speed is generally faster.
• It provides better security during transmission.
• It is cheaper.
• Easy to set up and install

Disadvantages

• Bandwidth is very low in guided media
• Susceptible to interference and noise.
• Requires physical link
• Not suitable for long distances
• Time consuming

Advantages And Disadvantages of Unguided Media

Advantages

• The signal is broadcasted through free space (air).
• It offers ease of communication over difficult terrains.
• Unguided signals can travel in several ways: sky propagation, ground propagation and line-of-sight propagation.
• Can successfully be used for long distance communication
• The electromagnetic spectrum, ranges from 3kHz to 900 THz use for wireless communication.

Disadvantages

• It has more effect on human health as compared to guided media.
• It is generally expensive.
• Transmission speed is generally slow.