Microwave Engineering Viva Questions and Answer 2023

This is a set of Microwave Engineering Viva/Interview Questions with Answers

1. What is frequency range of Microwave ?
Answer: Microwave frequencies range between 300MHz to 300 GHz with respective wavelengths of 1m to 1mm.

2. What is the Wavelength of microwave frequency ?
Answer: Microwaves have wavelengths approximately in the range of 1m (frequency = 300MHz) to 1 mm (300 GHz).

3. What are the frequency range of L, S, C, X, Ku, K and Ka Band ?

Answer:

L band: 1 GHz to 2 GHz
S band: 2 GHz to 4 GHz
C band: 4 GHz to 8 GHz
X band: 8 GHz to 12 GHz
Ku band: 12 GHz to 18 GHz
K band: 18 GHz to 26.5 GHz
Ka band: 26.5 GHz to 40 GHz

4. What is the biggest limitation of Microwave Communication ?
Answer: The biggest limitation is that microwaves are limited to line of sight propagation;
they can not pass around hills or mountains as lower frequency radio waves can.

5. What are the advantages of Microwave frequency ?
Answer: Following are advantages of Microwave frequencies-

• Larger Bandwidth: Due to larger bandwidth more data can be transmitted using microwaves.
  
• Better Directive Properties: It is easier to design and fabricate a high gain antenna as compared to low frequency signals.
  
• As the frequency increases, directivity increases and beam width decreases.
  
• Lower Power Requirement: The power required by the microwaves is very less as compared to low frequency signals.
  
• Fading effect: At microwave frequencies by using line of sight propagation technique, the amount of fading is minimized.

6. List the major applications of Microwaves?
Answer: Microwaves can be used in wide variety of applications like Military, Food industry, radio astronomy, medical applications, radar, semiconductor processing techniques, spectroscopy etc.

7. Give the frequency band of Infrared Rays (IR)?
Answer: The range of IR of the visible spectrum at is from 700 nanometers (nm) to 1 millimeter (mm). This leads to a frequency range of approximately 430 THz down to 300 GHz.

8. Discuss the band of visible Light?
Answer: The frequency band of light is from about 4 x 10¹⁴ to 8 × 10¹⁴ cycles per second, or hertz (Hz) and wavelengths ranges from 740 nanometers (nm) or 2.9 × 10⁻⁵ inches, to 380 nm (1.5 × 10⁻⁵ inches).

9. Mention the band of X Rays?
Answer: The frequency band of X rays ranges from10 picometres to 10 nanometres, and the frequencies ranges from 30 petahertz to 30 exahertz (3×10¹⁶ Hz to 3×10¹⁹ Hz).

10. What is the band of gamma Rays?
Answer: The frequency range of gamma rays are from 10²⁰ to 10²⁴ and the wavelength is less than 10^-12 m.

11. What is the formula for wavelength ?
Answer: λ= c/f
λ= wavelength of signal.
c= Speed of Light.
f= frequency of signal.

12. What are the advantages of Microwave frequency ?
Answer:

• Larger Bandwidth: Due to larger bandwidth more data can be transmitted using microwaves.
• Better Directive Properties: It is easier to design and fabricate a high gain antenna as compared to low frequency signals.
• As the frequency increases, directivity increases and beam width decreases.
• Lower Power Requirement: The power required by the microwaves is very less as compared to low frequency signals.
• Fading effect: At microwave frequencies by using line of sight propagation technique, the amount of fading is minimized.

13. What is the biggest limitation of Microwave Communication ?
Answer: A disadvantage is that microwaves are limited to line of sight propagation; they cannot pass around hills or mountains as lower frequency radio waves can.

14. Calculate wavelength for different frequencies 30MHz, 300MHz, 3GHz, 30GHz, 300GHz, 60MHz, 600MHz, 6GHz, 60GHz, 150GHz etc.
Answer: Here we are going to use this formula,
λ= c/f

15. What is the Microwave Oven frequency?
Answer: The energy in the microwave oven has a frequency of 2.45 GHz with a wavelength of 12.24 cm.

16. Which Band is free for Industrial & Medical application without license ?
Answer: Mainly 2.4GHz – 2.5GHz, 5.2GHz, 5.4GHz, 5.8GHz

17. What are the various Components of Microwave Systems ?
Answer:

• Transmitter
• Receiver
• Transmission Line
• Antennas

18. What is a Transmission line and explain the need for a Transmission Line?
Answer: Answer: Transmission line used as the medium which transmits energy from one point to another. The main use of transmission lines is to reduce power loss, dissipated as heat because of the resistance of the conductors. High voltage transmission lines are mostly used for long distance power transmissions.

19. What are the various types of transmission lines?
Answer: The different types of transmission lines are as follows:

• Wave Guide
• Two parallel wire
• Co-axial cable
• Microstrip
• Fiber Optic

20. What are the different types of losses in transmission lines?
Answer: The different types of transmission lines losses are as follows:

• Wave Guide
• Radiation (Induction) Losses
• Copper Losses
• Dielectric Losses

Microwave Engineering Viva Questions and Answer Part 2

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