Types of Transmission Media

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 and are chosen based on factors like distance, speed, and interference.

Types of Transmission Media

1. Guided Media

• Guided Media, also known as Wired or Bounded transmission media, directs and confines signals in a narrow pathway using physical links.

• Features: High speed, secure, used for shorter distances.

• Types of Guided Media:

  Twisted Pair Cable

  • Consists of two insulated conductor wires twisted together.
  • Types:
    • Unshielded Twisted Pair (UTP):
      • Blocks interference without a physical shield.
      • Used in telephonic applications.
      • Advantages: Least expensive, easy to install, high-speed capacity.
      • Disadvantages: Lower capacity and short-distance transmission due to attenuation.
    • Shielded Twisted Pair (STP):
      • Uses a special jacket to block external interference.
      • Used in fast Ethernet and telephone lines.
      • Advantages: Better performance at higher data rates, eliminates crosstalk.
      • Disadvantages: Difficult to install, expensive, bulky.

  Coaxial Cable

  • Has an outer plastic covering with insulation and parallel conductors.
  • Modes: Baseband and Broadband.
  • Advantages: High bandwidth, reliable and durable, less affected by interference.
  • Disadvantages: Expensive, must be grounded, bulky.

  Optical Fiber Cable

  • Uses light for data transmission via total internal reflection.
  • Advantages: Increased capacity and bandwidth, lightweight, immunity to interference.
  • Disadvantages: Difficult to install, high cost.
  • Applications: Medical instruments, defense, internet cables, automobile lighting.

  Stripline

  • A planar transmission line medium using conducting material sandwiched between ground planes.

  Microstripline

  • Used to carry high-frequency signals in microwave and RF circuits.

2. Unguided Media

• Also known as Wireless or Unbounded transmission media.

• Features: Signal broadcasted through air, less secure, used for larger distances.

• Types of Signals:

  Radio Waves

  • Easy to generate, penetrate buildings, used in AM and FM radios.
  • Types: Short wave, VHF, UHF.
  • Components: Transmitter and Receiver.

  Microwaves

  • Line-of-sight transmission; used for mobile phone communication.
  • Advantages: Cheaper than cables, ease of communication in difficult terrains.
  • Disadvantages: Insecure, limited bandwidth, high cost.

  Infrared

  • Used for short-distance communication, cannot penetrate obstacles.

Difference Between Radio Waves, Microwaves, and Infrared Waves

• Direction: Radio waves are omni-directional, while microwaves and infrared are unidirectional.
• Penetration: Radio waves can penetrate objects at low frequencies, microwaves vary by frequency, infrared cannot penetrate solid objects.
• Frequency Range: Radio (3 KHz to 1 GHz), Microwave (1 GHz to 300 GHz), Infrared (300 GHz to 400 THz).
• Security: Radio waves have poor security, microwaves have medium, and infrared offers high security.
• Attenuation: High for radio waves, variable for microwaves, low for infrared.
• Usage Cost: Radio and microwave setups are more costly; infrared is less expensive.

Causes of Transmission Impairment

• Attenuation: Loss of energy over distance, mitigated with amplifiers.
• Distortion: Changes in signal form, mainly in composite signals due to differences in propagation speed.
• Noise: Unwanted signals like induced noise, crosstalk, thermal noise, and impulse noise that may corrupt the transmission.

Factors Considered for Designing Transmission Media

• Bandwidth: Higher bandwidth leads to faster data transmission.
• Transmission Impairment: Signal quality is impacted by differences between sent and received signals.
• Interference: Disturbances or undesired signals affecting communication.

Applications of Transmission Media in Computer Networks

These notes provide an overview of the types of transmission media, their characteristics, and applications in computer networks.