Page 181 - PYTHON-12

8.12.2 Unguided Media or Wireless Networking Technologies

Features of Unguided Media:

1. Transmission and reception are achieved by means of an antenna.

2. Transmission can be either directional or omnidirectional.

(a) Directional
• transmitting antenna puts out focused beam
• transmitter and receiver must be aligned
(b) Omnidirectional

• signal spreads out in all directions
• can be received by many antennas
1. Microwave

Microwave signals are used to transmit data without the use of cable. It is a line-of-sight trans-
mission as signal travels in a straight line. In microwave communication, two directional parabolic
antennas are mounted on towers, buildings or hills to send and receive signals through air. However,
they must be properly aligned with each other, otherwise the signal will not be focused well at the
receiving antenna.
Secondary
Path
Direct Path

Fig. 8.29: Microwave

Advantages of Microwave Transmission

(a) It is a cheaper source of communication as it avoids using cables and maintaining repeaters.

(b) Communication through microwave is much easier over difficult terrain.
(c) Microwave system permits data transmission rate of about 16 gigabits per second.
Disadvantages of Microwave Transmission

(a) It is an insecure mode of communication.

(b) Signals can be split and propagated in different directions in air and received by the receiver
antenna with a reduced strength.
(c) Microwave propagation is affected by weather conditions such as rain, thunderstorm, etc.
Computer Networks
(d) The cost of implementing towers, antennas is relatively high.

8.27