Comms 3 (MOD 2)

Question 1

Types of waves

Answer 1

• mechanical
• electromagnetic

Question 2

Types of mechanical waves

Answer 2

• transverse
• longitudinal

Question 3

A wave that is an oscillation of matter and is responsible for the transfer of energy through a medium.

Answer 3

Mechanical wave

Question 4

A wave created by a fusion of electic and magnetic felds

Answer 4

Electromagnetic wave

Question 5

are wave from the portion of electromagnetic spectrum at lower frequencies than microwaves.

Answer 5

Radio waves

Question 6

Radio waves travel at the speed of

Answer 6

Light

Question 7

is the behavior of radio waves as they travel or are propagated from one point to another into various parts of the atmosphere

Answer 7

Wave propagation

Question 8

Radio waves properties

Answer 8

• can’t be felt or touched
• travel long distance/speed of light
• reflection, refraction, absorption, diffraction
• emitted by objects with changing magnetic field

Question 9

involves change in direction of waves when they bounce off a bartier.

Answer 9

Reflection

Question 10

the bending of the path of the waves, involves a change in the direction of waves as they pass from one medium to another.

Answer 10

Refraction

Question 11

change in direction of waves as they pass through an opening or around a barrier in their path.

Answer 11

Diffraction

Question 12

act as a waveguide for electromagnetic wave propagation.

Answer 12

Earth/ionosphere

Question 13

• 3 kHz to 30 kHz
• highly vulnerable to disturbance
• easily gets distorted by atmospheric changes.
• Scientists use this frequency band in seismic studies

Answer 13

Very Low Frequency (VLF)

Question 14

• 30 kHz to 300 kHz.
• Suitable for long-distance communication.
• Has less attenuation from big terrains

Answer 14

Low Frequency (LF)

Question 15

• 300 kHz to 3 MHz
• follows the curvature of the Earth
• cover regional distances,

Answer 15

Medium Frequency (MF)

Question 16

• 3 MHz to 30 MHz
• known for its skywave propagation
• ideal for long-distance communication

Answer 16

High Frequency (HF)

Question 17

• 30 MHz to 300 MHz
• most commonly used bands.
• usually affected by big terrains but is suitable for short-distance communication.

Answer 17

Very High Frequency (VHF)

Question 18

• 300 MHz to 3 GHz
• most important frequency band for modern wireless communication systems.
• signals generally require a direct line of sight.

Answer 18

Ultra High Frequency (UHF)

Question 19

• 3 GHz to 30 GHz.
• can only operate in a line of sight path.
• It is commonly used in point-to-point communication

Answer 19

Super High Frequency (SHF)

Question 20

• 30 GHz and 300 GHz.
• only used in advanced communication systems
• is used in radio astronomy and remote sensing

Answer 20

Extremely High Frequency (EHF)

Question 21

Three principle paths of radio waves

Answer 21

• ground wave
• sky wave
• space wave

Question 22

a method of radio wave propagation that uses the area between the surface of the earth and the ionosphere for transmission.

Answer 22

Ground wave

Question 23

A type of radio wave communication in which the electromagnetic wave propagates due to the reflection mechanism of the ionospheric layer of the atmosphere.

Answer 23

Sky wave

Question 24

Defined for the radio waves that occur within the 20km of the atmosphere, consisting of a direct and reflected wave

Answer 24

Space wave

Question 25

It is also known as a line of sight propagation

Answer 25

Space wave

Question 26

Advantages of Ground Wave Propagation

Answer 26

- Large wavelength/Less attenuation - Signal loss is less

Question 27

Disadvantages of Ground Wave Propagation

Answer 27

- Transmitters and Receiver must be close - operational frequency range is limited to up to 2MHz

Question 28

Advantages of sky wave propagation

Answer 28

- Large distance propagation - Frequency range is high - attenuation is less

Question 29

Disadvantages of sky wave propagation

Answer 29

- Long-distance propagation requires large-sized antennas - variation in signal transmission

Question 30

Disadvantage of space wave

Answer 30

Obstacle causes attenuation

Question 31

Structure of ionosphere

Answer 31

- D - E - F1 - F2

Question 32

Length of ionosphere

Answer 32

60-400km

Question 33

due to ___ on the atmosphere, EM wave gets reflected back towards the surface of the earth

Answer 33

Ionization

Question 34

A type of radio wave communication in which the electromagnetic wave propagates due to the reflection mechanism of the ionospheric layer of the atmosphere.

Answer 34

Sky wave

Question 35

Defined for the radio waves that occur within the 20km of the atmosphere, consisting of a direct and reflected wave

Answer 35

Space wave

Question 36

a method of radio wave propagation that uses the area between the surface of the earth and the ionosphere for transmission.

Answer 36

Ground wave