This document discusses different types of transmission media including fiber optic cables, radio waves, microwaves, and infrared transmission. It provides details on how each type of media transmits signals and their applications. Fiber optic cables transmit light signals over glass fibers using converters, and offer advantages like high bandwidth, low attenuation, and immunity to electromagnetic interference. Radio waves transmit signals through the air and are used for applications like radio, TV, and cordless phones. Microwaves also transmit through the air but in a line-of-sight manner and are used for cellular networks and wireless LANs. Infrared transmission uses light frequencies for short range uses like remote controls.

1. Towards its source side there is a converter that converts
electrical signals into light waves. These light waves are
transmitted over the fiber. Another converter placed near the sink
converts the light waves back of electrical signals. These electrical
signals are amplified and sent to the receiver. Fiber-optic
transmission systems are already in the market, and their
popularity is growing rapidly.

2. 1. Advantages
1. Higher bandwidth
Fiber-optic cable can support dramatically higher
bandwidths (and hence data rates) than either twisted-pair
or coaxial cable.
2. Less signal attenuation
Fiber-optic transmission distance is significantly greater
than that of other guided media. A signal can run for 50
km without requiring regeneration. We need repeaters
every 5 km for coaxial or twisted-pair cable.
3. Provide high quality (low error rate) transmission.

3. 4. Immunity to electromagnetic interference
Electromagnetic noise can not affect fiber-optic cables.
5. Resistance to corrosive materials
Glass is more resistant to corrosive materials than
copper.
6. Light Weight
7. Can be used for both analog and digital data
transmission.
8. There are no chances of any sparking, which
results into a safer system.
9. Glass is immune to corrosive and oxide
degradation and thus will standup well in hostile
environments.

4. Disadvantages
1. High Cost
The cable and the interfaces are relatively more expensive than
those of other guided media.
2. Unidirectional light propagation
Since optical transmission is inherently unidirectional, two -way
communication requires either two fibers or two frequency bands
on one fiber.
3. Installation and Maintenance
Fiber is an unfamiliar technology requiring skills, most engineers
do not possess.
4. It is limited to fixed point-to-point ground installations

5. Unguided Media
It refers to the method of Transmission through the
air/atmosphere. In this Media there is no Cabling. The signals are
broadcast in the air and thus are available to anyone, who has a
device capable of receiving them.

6. Radio waves have frequencies between 10kHz and 1 gigahertz.
The range of electromagnetic spectrum between 10kHz and 1
GHz is called radio frequency (RF).
Radio waves, for the most part, are omni directional. When an
antenna transmits radio waves, they are propagated in all
directions. This means that the sending and receiving antennas
do not have to be aligned. A sending antenna sends waves that
can be received by any receiving antenna. Based on the
wavelength, strength, and the purpose of transmission, we can
have several types of antennas as shown in figure 4.8.
Radio waves, particularly those waves that propagate in the sky
mode, can travel long distances. Radio waves, particularly
those of low and medium frequencies, can penetrate walls.
Therefore, an AM radio can receive signals inside a building
also.

7. Radio waves are very easy to generate and they can travel
long distances. Due to these reasons, they are widely used
for indoor and outdoor communication.
These are the waves through which your walky-talky sets
and radio operates. Defense people on the fronts also use
this type of communication.

8. Applications
1. AM and FM radio
2. TV
3. Cordless Phones
4. Paging
5 Walky-Talky sets

9. Advantages
1. Radio waves offer mobility at cheaper cost.
2. It has a very low setup cost as it does not require
digging and laying the cables.
3. Radio waves can travel long distances.
4. Radio waves can penetrate wall, so we can also
receive signals inside a building.
5. No land acquisition right is needed.
It offers ease of communication in difficult geographical
conditions

10. Disadvantages
1. It is an insecure and easy to tap communication.
2. It gets effected by weather effects like rains, thunder
storms etc.

11. Main characteristic of Microwaves are:
1. Microwaves are unidirectional. the sending and
receiving antennas need to be aligned.
2. Microwave propagation is line-of-sight
3. Very high-frequency microwaves cannot penetrate
walls.
4. The microwave band is relatively wide, almost 299
GHz. Therefore wider sub bands can be assigned, and a high
data rate is possible.
5. Use of certain portions of the band requires permission
from authorities.

12. Main applications of microwaves are
1. Cellular phones
2. Satellite networks
3. Wireless LAN

13. Advantages
1. High data transmission rate.
2. High capacity to carry large quantities of data.
3. Lower error rate thus making it more reliable as
compared to wire-cable.
5. Microwaves offer communication over very long
distances.
6. They have better performance in bad weather conditions
than radio waves.

14. Disadvantages
1. Very costly
2. Electromagnetic waves cannot bend or pass through
obstacles like mountains etc.
3·Microwave signals are vulnerable to electromagnetic
interference (EML).
4. Microwave systems are also affected by atmospheric
conditions.
5. It is also an insecure and easy to tap communication.
6. This communication offers limited bandwidth

15. Infrared Transmission
Infrared waves, with frequencies from 300 GHz to 400 THz
can be used for short-range communication.
You must have used this communication while changing a
channel of television using remote control or while
transferring data from your mobile to your computer. Both
these communications use infrared communication.
Infrared waves, having high frequencies, cannot penetrate
walls, therefore a short-range communication system in one
room cannot be affected by another system in the next
room. However, this same characteristic makes infrared
signals useless for long-range communication.
In addition, we cannot use infrared waves outside a building
because the sun's rays contain infrared waves that can
interfere with the communication.

16. Applications
• Infrared signals can be used for short-range communication.
• Wireless alternative to connecting devices such as laptop to a
printer.
• In remote control devices for TV, AC, DVD etc.
• cordless devices like keyboards, mice, joysticks, printers etc.
use Infrared signals for communication
• Now-a-days, some manufacturers provide a special port called
IrDA port that allows a wireless keyboard to communicate with
a PC.
• Infrared band can be used in development of very high speed
wireless LANs in future.

17. Advantages
1. High speed
2. Large bandwidth
3. Very cheep
4. Easy to generate
5. Provide wireless connection between
two devices.
6. No license is required to use it.

18. Disadvantages
1 Cannot penetrate walls.
2. We cannot use infrared waves outside a
building.
3. Cannot used for long-range communication.