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EngineeringNotes
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Chapter 03

Transmission Media

The physical highways that carry data across the world.

01

Guided Media (Wired)

Signals are guided along a solid medium. Also known as "Wired" communication.

Twisted Pair Cable

Two copper wires twisted together to cancel out electromagnetic interference (EMI) from external sources and crosstalk.

  • Type: UTP (Unshielded) & STP (Shielded)
  • Connector: RJ45
  • Usage: LANs, Ethernet
  • Cost: Low

Coaxial Cable

Central copper core surrounded by insulation, a metal shield, and an outer cover. Supports higher frequency ranges.

  • Bandwidth: High
  • Connector: BNC
  • Usage: Cable TV
  • Noise Resistance: High

Fiber Optic Cable

Transmits data as pulses of light through glass or plastic strands. Uses Total Internal Reflection.

  • Speed: Very High (Gbps)
  • Distance: Long Range
  • EMI: Immune
  • Cost: High
02

Unguided Media (Wireless)

Signals travel through free space (air/vacuum). No physical conductor.

Radio Waves

Omnidirectional (signals spread in all directions). Can penetrate walls.

FM Radio, TV, WiFi

Microwaves

Unidirectional (Line-of-Sight). Cannot penetrate solid objects like walls. Precision focused.

Satellites, Cellular

Infrared

Short-range communication. Cannot pass through obstacles. Used for device-to-device.

Remotes, Mouse