ICT 305
Data Com m u nication
System s and Netw or k
By
Dr. B . K . Nu h u
,Wireless Transmission
• Transmission and reception is via
antennas
• For transmission, the antenna radiates
electromagnetic energy into the medium
(usually air), and for reception, the
antenna picks up electromagnetic waves
from the surrounding medium.
• There are basically two types of
configurations for wireless transmission:
directional and Omni-directional
,• For the directional configuration, the
transmitting antenna puts out a focused
electromagnetic beam; the transmitting and
receiving antennas must therefore be
carefully aligned.
• In the omnidirectional case, the transmitted
signal spreads out in all directions and can be
received by many antennas.
• the higher the frequency of a signal, the more
it is possible to focus it into a directional
beam
, Wireless Transmission Frequencies
• 2GHz to 40GHz (Microwave Frequencies)
—Highly directional
—Suitable for Point-to-point transmission
—Used for Satellite Communications.
—(Gigahertz = 109HZ)
• 30MHz to 1GHz (Broadcast Radio Range)
—Suitable for Omnidirectional applications
• 3x1011 to 2x1014Hz (Infrared for local
applications)
—Infrared is useful to local point-to-point and
multipoint applications within confined areas,
such as a single room.
Data Com m u nication
System s and Netw or k
By
Dr. B . K . Nu h u
,Wireless Transmission
• Transmission and reception is via
antennas
• For transmission, the antenna radiates
electromagnetic energy into the medium
(usually air), and for reception, the
antenna picks up electromagnetic waves
from the surrounding medium.
• There are basically two types of
configurations for wireless transmission:
directional and Omni-directional
,• For the directional configuration, the
transmitting antenna puts out a focused
electromagnetic beam; the transmitting and
receiving antennas must therefore be
carefully aligned.
• In the omnidirectional case, the transmitted
signal spreads out in all directions and can be
received by many antennas.
• the higher the frequency of a signal, the more
it is possible to focus it into a directional
beam
, Wireless Transmission Frequencies
• 2GHz to 40GHz (Microwave Frequencies)
—Highly directional
—Suitable for Point-to-point transmission
—Used for Satellite Communications.
—(Gigahertz = 109HZ)
• 30MHz to 1GHz (Broadcast Radio Range)
—Suitable for Omnidirectional applications
• 3x1011 to 2x1014Hz (Infrared for local
applications)
—Infrared is useful to local point-to-point and
multipoint applications within confined areas,
such as a single room.
