EC-702-A Microwave Engineering - Nov 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWrite an introductory note on Microwave Signals. Elaborate some of the practical applications of microwaves.
   How to answer

   • Define microwave frequency range and signal characteristics
   • Describe generation, propagation and key properties
   • List practical applications - communication, radar, medical, industrial heating
2. 7 Marks
   bGive a brief comparison on micro strip lines and slot lines with suitable examples.
   How to answer

   • Describe microstrip line structure and field
   • Describe slot line structure and field
   • Compare on parameters with examples
3. 7 Marks
   aA rectangular waveguide with dimension of $3\times 2$ cm operates in TM11 mode at $10$ GHz. Determine the characteristic wave impedance.
   How to answer

   • Calculate cutoff frequency $f_c$ for $TM_{11}$ mode
   • Calculate $\eta = 120\pi$ and $Z_{TM}=\eta\sqrt{1-(f_c/f)^2}$
   • Substitute $a=3$ cm, $b=2$ cm, $f=10$ GHz to get value
4. 7 Marks
   bWhat are the different solid state microwave sources use in industries? Explain its practical uses in today's world.
   How to answer

   • List solid-state sources: Gunn, IMPATT, TRAPATT, Tunnel, PIN, varactor
   • Explain operating principle briefly
   • Discuss practical uses in industry, communication, radar, medical
5. 7 Marks
   aDerive and analyze the results of S parameters in microwave circuits.
   How to answer

   • Define incident/reflected waves and S-matrix
   • Derive $S$-parameters from port relations
   • Analyze properties: reciprocity, losslessness, return loss
6. 7 Marks
   bElaborate the dominant and higher order modes in strip line structure.
   How to answer

   • Describe stripline structure and TEM dominant mode
   • Explain higher order TE/TM modes and cutoff
   • Discuss field distribution and suppression
7. 7 Marks
   aDerive a relation for frequency multipliers. Discuss its operating principle to be use in different microwave devices.
   How to answer

   • Define frequency multiplier with nonlinear device
   • Derive output frequency relation $f_{out}=n f_{in}$
   • Discuss principle and use in microwave sources
8. 7 Marks
   b"Impedance transformer plays a vital role in microwave devices". Support your answer with some practical application work.
   How to answer

   • Define impedance transformer and need for matching
   • Explain quarter-wave and multisection types
   • Give practical microwave applications
9. 7 Marks
   aDerive a basic relations for Microwave BJT and FET circuits.
   How to answer

   • Give equivalent circuits of microwave BJT and FET
   • Derive gain, cutoff and power relations
   • Discuss high-frequency limitations
10. 7 Marks
    bDraw and explain the block diagram of frequency converters using Schottky diodes.
    How to answer

    • Draw block diagram with Schottky diode mixer/converter stages
    • Explain RF, LO, IF signal flow and filtering
    • Discuss conversion principle and applications
11. 7 Marks
    aDiscuss various modes of operation of Tunnel diode and Gunn Diode.
    How to answer

    • Explain Tunnel diode negative resistance modes
    • Explain Gunn diode transferred electron modes
    • Compare operating mechanisms and uses
12. 7 Marks
    bDerive the equation of Voltage Standing Wave Ratio (VSWR) in terms of reflection coefficient.
    How to answer

    • Define reflection coefficient $\Gamma$ and standing wave
    • Derive $VSWR = (1+|\Gamma|)/(1-|\Gamma|)$
    • Discuss matched and mismatched cases
13. 7 Marks
    aExplain the diode phase shifter. Discuss the principle of broadband and tuned detectors.
    How to answer

    • Explain diode phase shifter types and operation
    • Describe broadband detector principle
    • Describe tuned detector principle
14. 7 Marks
    bExplain YIG resonator. Analyze your answers and elaborate their practical known applications.
    How to answer

    • Define YIG resonator and ferrimagnetic resonance
    • Analyze tuning and Q-factor characteristics
    • List applications in filters, oscillators, YIG-tuned sources
15. 14 Marks
    Write short note (any four)

    1. a)Reflex klystron
    2. b)TEM mode of operation
    3. c)Circulators
    4. d)Isolators
    5. e)IMPATT
    How to answer

    • Define principle and structure of chosen device
    • Explain working with diagram where needed
    • Mention characteristics and microwave applications