EC8701 ANTENNAS AND MICROWAVE ENGINEERING-AMW Question Bank with Answers Pdf

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EC8701 ANTENNAS AND MICROWAVE ENGINEERING-AMW Question Bank with Answers Pdf

ANTENNAS AND MICROWAVE ENGINEERING-AMW Question Bank with Answers Pdf
ANTENNAS AND MICROWAVE ENGINEERING-AMW Question Bank with Answers Pdf

UNIT I : INTRODUCTION TO MICROWAVE SYSTEMS AND ANTENNAS

Microwave frequency bands, Physical concept of radiation, Near- and far-field regions, Fields and Power Radiated by an Antenna, Antenna Pattern Characteristics, Antenna Gain and Efficiency, Aperture Efficiency and Effective Area, Antenna Noise Temperature and G/T, Impedance matching, Friis transmission equation, Link budget and link margin, Noise Characterization of a microwave receiver.

1. Sketch electromagnetic frequency spectrum showing the location of RF and Microwave frequency bands.

2. What are microwaves?

3. List the conditions under which wire radiates.

4. Define reactive near field region of antenna.

5. Define radiating near field region( Fresnel region) of antenna.

6. Define far field( Fraunhofer) region of antenna

7. A parabolic reflector antenna used for reception with the direct broadcast system (DBS) is 18 inches in diameter and operates at 12.4 GHz. Find the far-field distance for this antenna.

8. Define Radiation Intensity. What is it’s significance?

9. Define Radiation pattern.

10. Define Half Power Beam Width (HPBW) of an antenna.

11. Define beam solid angle.

12. Define Beam Width between First Null.

13. Define main lobe, side lobe, minor lobe and back lobe with reference to antenna radiation pattern.

14. Define directivity of an antenna.

15. What do you mean by an isotropic radiator? What is the directivity of isotropic radiator?

16. What is the Relationship between Directivity and beamwidth?

17. Define omnidirectional antenna. Give its applications

18. Define pencil beam antenna and give its applications

19. Define radiation efficiency of antenna.

20. Define gain of an antenna. What is the significance of gain of an antenna?/ Relate the gain and directivity of an antenna through proper expression.

21. Define aperture efficiency.

22. Define effective aperture area. What is the relation between effective aperture area and Directivity(gain)?

23. Define Antenna Brightness temperature

24. What is the significance of G/T ratio?

25. State why impedance matching(tuning) is important.

26. Give the Friis radio link formula.

27. Define EIRP. What is the significance of this quantity?

28. Define path loss.

29. Define link margin

30. Define fade margin.

31. How link margin for a given communication system can be improved?

32. What is point-to-point communication.Mention some of its application.

33. An antenna has a field pattern given by E(θ) = cos2 θ for 0° < θ < π. Find Half Power Beam Width (HPBW).

34. What is Link Budget ? Mention a simple Link Budget equation.

ANTENNAS AND MICROWAVE ENGINEERING-AMW Unit Wise 16 Marks Important Questions

UNIT II : RADIATION MECHANISMS AND DESIGN ASPECTS

Radiation Mechanisms of Linear Wire and Loop antennas, Aperture antennas, Reflector antennas,Microstrip antennas and Frequency independent antennas, Design considerations and applications.

1. State Huygens Principle

2. State Babinet’s principle and how it gives rise to the concept of complementary antenna?

3. State uniqueness theorem 

4. What is field equivalence principle?

5. Draw various types of Horn antenna

6. Distinguish between sectoral horn and pyramidal horn.

7. The aperture dimensions of a pyramidal horn are 12x6 cm and operating at a frequency of 10 GHz. Find the beam width and directivity. 

8. What are secondary antennas? Give two examples.

9. What is a corner reflector?

10. What is the main advantage of Cassegrain reflector configuration?

11. What is the main disadvantage of Cassegrain reflector configuration?

12. What is slot radiator? What is its operating principle?

13. Write any two differences between slot antenna and its complementary dipole antenna.

14. The impedance of an infinitesimally thin λ/2 antenna is 73+j42.5 Ω. Calculate the terminal impedance of an infinitesimally thin λ/2 slot antenna.

15. What is a microstrip antenna?

16. What are the features of microstrip antennas?

17. What are the major operational disadvantages of microstrip antennas?/ Point out the limitations of microstrip patch antennas.

18. List the different methods of feeding Microstrip antenna.

19. Define the bandwidth of an antenna.

20. What is wide band antenna? Give an example.

21. State Rumsey principle on frequency independence.

22. What is LPDA?

23. Why is log periodic antennas called so?

24. Calculate the beam width between first nulls of a 2.5 m paraboloid reflector used at 6 GHz.

25. What is aperture blockage ? Give one example. 

26. Discuss the merits and applications of offset feed reflector antenna.

EC8701 ANTENNAS AND MICROWAVE ENGINEERING- AMW Syllabus

UNIT III :  ANTENNA ARRAYS AND APPLICATIONS

Two-element array, Array factor, Pattern multiplication, uniformly spaced arrays with uniform and non-uniform excitation amplitudes, Smart antennas.

1. What is an antenna array?

2. What is a Linear Array?

3. Define uniform linear array

4. Why we go for non-uniform amplitude distribution?

5. Distinguish between uniform and non-uniform arrays.

6. What is uniform Array?

7. What are the factors that decide the radiation characteristics of array?

8. Define Grating lobes

9. What is end-fire array?

10. Give the condition to have only one end-fire maximum.

11. What is broad-side array?

12. A uniform linear array contains 50 isotropic radiators with an inter element spacing of λ/2 .Find the directivity of broadside forms of arrays. 

13. What is tapering of arrays? 

14. What are the advantages of antenna arrays? 

15. Draw the radiation pattern for a linear array of two isotropic elements spaced λ/2 apart and with equal current fed in phase. 

16. Draw the radiation pattern of an isotropic point sources of same amplitude and opposite phase that are λ/2 apart along X-axis symmetric with respect to origin. 

17. A uniform linear array of 4 isotropic elements with an inter element spacing of λ/2 . Find the BWFN and directivity of end fire arrays.

18. How number of array elements effect directivity?

19. What is the advantage of pattern multiplication?

20. State the principle of pattern multiplication 

21. Using pattern multiplication find the radiation pattern for the broadside array of 4 elements,spacing between each element is λ/2./ Illustrate the pattern multiplication principle.

22. What is the practical major disadvantage of Binomial array?

23. What is the main advantage of Binomial array?

24. What is binomial array?

25. What are the advantages of Dolph-Tschebyscheff array?

26. What is Phased arrays ?

27. Define adaptive array(smart antennas). / Illustrate the features of smart antennas.

28. What is reconfigurable antenna ?

ANTENNAS AND MICROWAVE ENGINEERING-AMW LAB VIVA

UNIT IV :  PASSIVE AND ACTIVE MICROWAVE DEVICES

Microwave Passive components: Directional Coupler, Power Divider, Magic Tee, attenuator, resonator, Principles of Microwave Semiconductor Devices: Gunn Diodes, IMPATT diodes Schottky Barrier diodes, PIN diodes, Microwave tubes: Klystron, TWT, Magnetron

1. Define any two performance factors of directional couplers. List out the different types of directional couplers.

2. Name some uses of waveguide Tees. What are the two different types of waveguide Tees?

3. Write the application of magic Tee.

4. What is hybrid ring or Rat-Race junctions?

5. What is negative resistance in Gunn diode? 

6. A Directional coupler is having coupling factor of 20dB and directivity of 40dB. If the incident power is 900mW, what is the coupled power?

7. What are the various materials used for Gunn diodes? What are the four different modes of operation of GUNN diode?

8. Mention the applications of IMPATT diode.

9. What is Gunn Effect?

10. Compare PIN and PN diode.

11. Draw the equivalent circuit of a Gunn diode.

12. List out the different types of Magnetrons.

13. Explain Hull Cut-off condition.

14. What is the purpose of slow wave structures in TWT? Name them.

15. List the advantages of Reflex klystron over multi-cavity klystrons.

16. Explain the need for attenuators in TWT.

17. What is meant by velocity modulation? 

18. Define transit time in a Reflex klystron.

19. Bring out the differences between the TWT & Klystron 

20. What do you meant by bunching?

21. Write the application of Reflex klystron

22. What are the classifications of Microwave tubes and explain the difference between them.

23. Write the application of backward wave oscillator.

24. Define Electronic Admittance.

25. What is drift space?

26. What is magnetron? 

27. What do you mean by O type tube? Name some O type tubes.

28. How to minimize the lead inductance and inter electrode capacitance.

29. Distinguish between O-type and M-type tubes.

30. Give two examples for reciprocal microwave passive device.

31. A Reflex Klystron is operated at 10 GHz with a dc beam voltage of 600 V for 1 3/4 mode, repeller space length of 1 mm and dc beam current of 12 mA. The beam coupling co-efficient is assumed to be 1. Calculate the repeller voltage.

32. A directional coupler is having coupling factor of 20 dB and directivity of 40 dB. If the incident power is 800 mW, what is the coupled power?

33. Specify the scattering matrix of a multi hole directional coupler

EC8701 ANTENNAS AND MICROWAVE ENGINEERING- AMW Notes

UNIT V:  MICROWAVE DESIGN PRINCIPLES

Impedance transformation, Impedance Matching, Microwave Filter Design, RF and Microwave Amplifier Design, Microwave Power amplifier Design, Low Noise Amplifier Design, Microwave Mixer Design, Microwave Oscillator Design

1. What do you mean by impedance matching? 

2. Why impedance matching is significant in a microwave system?

3. List out the factors that may be important in the selection of a particular matching network?

4. Define a filter.

5. Write about microwave filter implementation.

6. State the principle behind Richards’ transformation

7. What is the role of Kuroda’s Identities in filter implementation?

8. Sketch Richard’s transformation

9. Sketch the four Kuroda Identities.

10. Mention the significance of Microwave transistor amplifiers.

11. List out the usual microwave amplifier design goals.

12. Define Power gain.

13. Define Available power gain. 

14. Define Transducer power gain. Define transducer power gain of amplifier

15. State the conditions that are necessary and sufficient for unconditional stability.

16. What is the idea behind LNA design?

17. Define noise figure.

18. Give the noise figure expression for a cascaded system.

19. What is role of power amplifiers in transmitters?

20. List out the types and characteristics of power amplifiers.

21. Define a mixer.

22. The IS-54 digital cellular telephone system uses a receive frequency band of 869– 894 MHz, with a first IF frequency of 87 MHz and a channel bandwidth of 30 kHz. What are the two possible ranges for the LO frequency? If the upper LO frequency range is used, determine the image frequency range. Does the image frequency fall within the receive passband?

23. Define conversion loss in a mixer.

24. How are oscillators designed for microwave frequencies?

25. Compare and contrast diode-based and transistor-based oscillators.

26. Why is it necessary to go for microstrip line matching networks?

27. Sketch the frequency response characteristics of ideal Band pass filter and ideal High pass filter.

ANTENNAS AND MICROWAVE ENGINEERING-AMW  QB PDF :-  Download

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