Transmission Media:
Transmission media is
a pathway that carries the information from sender to receiver. We use
different types of cables or waves to transmit data. Data is transmitted
normally through electrical or electromagnetic signals.
An electrical signal is
in the form of current. An electromagnetic signal is series of electromagnetic
energy pulses at various frequencies. These signals can be transmitted through
copper wires, optical fibers, atmosphere, water and vacuum Different Medias
have different properties like bandwidth, delay, cost and ease of installation
and maintenance. Transmission media is also called Communication channel.
Types of Transmission
Media:
Transmission media is broadly classified into two groups.
1. Wired or Guided Media or Bound Transmission Media
2. Wireless or Unguided Media or Unbound Transmission Media
Wired or Guided Media or Bound Transmission Media:
Band transmission media are the cables that are tangible or have physical existence
and are limited by the physical geography. Popular band transmission media in use are twisted pair cable,
co-axial cable and fiber optical cable. Each
of them has its own characteristics like transmission speed, effect of noise,
physical appearance, cost etc.
Wireless or Unguided Media or Unbound Transmission Media:
Unbound transmission
media are the ways of transmitting data without using any cables. These media
are not bounded by physical geography. This type of transmission is called Wireless communication. Nowadays wireless communication is becoming
popular. Wireless LANs are being installed in office and college campuses. This
transmission uses Microwave, Radio wave, Infra red are some of popular unbound transmission
media.
The data transmission capabilities of various Medias vary
differently depending upon the various factors. These factors are:
1. Bandwidth.
It refers to the data carrying capacity of a channel or
medium. Higher bandwidth communication channels support higher data rates.
2. Radiation.
It refers to the leakage of signal from the medium due to
undesirable electrical characteristics of the medium.
3. Noise Absorption.
It refers to the susceptibility of the media to external electrical
noise that can cause distortion of data signal.
4. Attenuation.
It refers to loss of energy as signal propagates outwards.
The amount of energy lost depends on frequency. Radiations and physical
characteristics of media contribute to attenuation.
