Transmission medium

Transmission Media

It is a path through which information signal travels from source to destination. It is also known as Transmission Line or Transmission channel.
It is further divided into two categories

  • Guided Media.
  • Unguided Media.

Guided / Bounded /Wired Media

Guided media provides physical facility (Channel, Tube, or physical path) to transmit signal. Only physically connected devices can transmit or receive signal. A physical facility is one that which occupies space and has weight.


  • Twisted Pair
  • Coaxial Cable

Non Metallic

Parallel Conductor Transmission Line / Twisted Pair Cable

Open Wire Transmission Line

  • Simple construction.
  • High radiation loss
  • High EMI.
  • Low cost

Twin Lead

  • Fixed dielectric material is used

Twisted Pair Transmission Line

Pairs are twisted with different lengths to minimize the effect of electromagnetic interference Number of twist per cm physically identifies the CAT number.

Coaxial Cable

  • Costly as compared to twisted pair.
  • Initially used for high bit rate but Now CAT 7 and 8 offer higher data rate.
  • Outer Conductor shield provide resistance to external electromagnetic interference.
  • It is more secure than twisted pair cable.

It is further divided into two categories

  • Baseband Coaxial cable
  • Broadband Coaxial cable

Fiber Optic Cable

We have already discussed everything about FOC

Unguided / Unbounded /Wireless Media

Atmosphere is used as a transmission medium The direction of propagation depends on the direction in which the signal emitted.
Electromagnetic wave with frequencies from 3 KHz to 300 GHz are generally classified as radio waves. However, radio waves with frequencies between 300 MHz and 300 GHz are technically classified as microwaves. Hence, microwaves are essentially radio waves with higher frequencies

  • Physical Path not required
  • Due to high frequency (microwave), they can carry high data.
  • Less maintenance.

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