# Propagation Mechanism

Jun 29 • General • 3437 Views • No Comments on Propagation Mechanism

# Free-space path loss (FSPL)-

It is the loss in strength of the signal of an electromagnetic wave that would result from a line-of-sight path through free space which may be air, with no obstacles nearby to cause diffraction or reflection. It does not include factors such as the antenna gain used at the receiver or transmitter,nor any loss associated with imperfections in hardware.Free-space path loss is directly proportional to the square of the distance between the transmitter and receiver which is proportional to the square of the frequency of the radio signal used.

Reflection –

It is the change in direction of a wave at an interface between two different medium so that the wave returns into the medium from which it originates. Common examples of reflection include the reflection of sound, light, water waves. The law of reflection says that for reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected back.  Example of Reflection

Transmission-

It is the process of sending and propagating an analog or digital signal over a physical point-to-point or point-to-multipoint transmission channel i.e,  wired, optical fiber or wireless communication. Transmission technologies and the schemes typically refer to physical layer protocol duties that is modulation, demodulation,equalization,line coding ,error control, bit synchronization and multiplexing but it may also involve higher-layer protocols such as digitizing an analog message signal, and source coding.Transmission of a digital message is known as  digital communication.

Antenna is used for transmission of radio signals.

1.What are the factors not included in free space path loss?

Ans.It does not include factors such as the antenna gain used at the receiver or transmitter,nor any loss associated with imperfections in hardware.

2. What does the law of reflection states ?

Ans. Law of reflection states that  for reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected back.

3. What are the types of channels used for transmission?

Ans. The  transmission channels used may be  wired, optical fiber or wireless.

4.What are the schemes used in transmission?

Ans.Schemes used in transmission are modulation, demodulation,equalization,line coding ,error control, bit synchronization and multiplexing.

5.Transmission of a digital message is known as what?

Ans..Transmission of a digital message is known as  digital communication.

IES SYLLABUS:

IES Syllabus for Electronics and Telecommunication

IES Syllabus for General Ability

GATE SYLLABUS:

GATE  Syllabus for Electronics and Communication