this is a presentation on guided and unguided media .

1. Computer Project Work
Guided And Unguided Media

2. Guided Media
Guided Transmission Media uses a cabling system
that guides the data signals along a specific path
. The data signals are bound by the cabling
system . Guided Media is also known as Bound
Media or Wired media . There three basic
types of Guided Media :
1. Twisted Pair
2. Coaxial Cable
3. Optical Fiber

3. 1. Twisted Pair Cable
• Pair of twisted conductors
•Twisting reduces interference (two parallel wires constitute a
simple antenna; a twisted pair does not.)
•Cheap medium
•Commonly used for communications within buildings and in
telephone networks
•Produced in unshielded (UTP) and shielded (STP) forms, and in
different performance categories.
•Cables may hold hundreds of pairs. Neighbor pairs typically have
different twist lengths to reduce crosstalk.

4. 2. CoaxialCable
Coaxial Cable consists of
2 conductors. The inner
conductor is held inside
an insulator with the
other conductor woven
around it providing a
shield. An insulating
protective coating called a
jacket covers the outer
conductor.

5. 3. Optical Fiber
• Three components: light source, transmission system, and a detector .
• The detector generates an electric pulse when hit by light
• 1-a pulse of light; 0-missing pulse of light.
• optical rays travel in glass or plastic core
• Light at shallow angles propagate along the fibre, and those that are less than critical angle are
absorbed in the jacket
• The cladding is a glass or plastic with properties that differ from those of the core
• Used in long distance communication, in locations having small amount of space, and with
reduction in price is starting to get also to LANs.
• Not affected by external electromagnetic fields, and do not radiate energy. Hence, providing
high degree of security from eavesdropping.
• Provide for multimode of propagation at different angles of reflections. Cause signal elements
to spread out in time, which limits the rate in which data can be accurately received.
• Reduction of the radius of the core implies less reflected angles. Single mode is achieved with
sufficient small radius.
• A multimode graded index transmission is obtained by varying the index of reflection of the
core to improve on the multi mode option without resolving to the cost of single mode. (index
of reflection=speed in vacuum / speed in medium.)
• 1 Gbps is the current limitation, with the bottle neck in the conversion from electrical to
optical signals. Large improvements are expected.

6. Unguided Media
• Here information is transmitted by sending
electromagnetic signals through free space and
hence the name unguided media, as the signals are
not guided in any specific direction or inside any
specific medium.
• All unguided media transmission are classified as
wireless transmission.
• Wireless transmission can be used as the medium in
both LAN and WAN environments.

7. Some of the types of wireless media are:
• RADIO WAVES
• MICRO WAVES
• INFRARED WAVES

8. 1. Radio Wave
• Although there is no clear limit distinction between radio
waves and microwaves,
• electromagnetic waves ranging in frequencies between 3
kHz and 1 GHz are normally
• called radio waves; waves ranging in frequencies between 1
and 300 GHz are called
• microwaves. However, the behavior of the waves, rather
than the frequencies, is a better
• criterion for classification.
• Radio waves, particularly those of low and medium
frequencies, can penetrate
• walls.

9. 2. Microwave
Microwave signals are
used to transmit data
without the use of cables,
similar to that of radio
and television signals but
at different frequency
range . It is line-of-sight
transmission , which
means the signal travels
in straight line free of
material obstacles .

10. 3. Infrared
This type of transmission uses infrared light to send data. You
can see the use of this type of transmission in everyday life -
TV remotes, automotive garage doors, wireless speakers
etc., all make use of infrared as transmission media.
The infrared light transmits data through the air and can
propagate throughout a room(bouncing off surfaces), but
will not penetrate walls. The infrared transmission has
become common in PDAs(Personal digital assistants)e.g.,
hand held devices like palm pilots etc.