Download VTU B-Tech/B.E 2019 June-July 1st And 2nd Semester 2015 June-July 14ELE15 Basic Electrical Engineering Question Paper

VASAVI COLLEGE OF ENGINEERING (Autonomous), HYDERABAD

B.E. (ECE) VI Semester Main Examinations, May-2019

Microwave Engineering (Open Elective-II)

Time: 3 hours                                                                                                                      Max. Marks: 70

Note: Answer ALL questions in Part-A and any FIVE from Part-B

Part-A (10 x 2 = 20 Marks)

1. Define the terms: (a) Cut-off frequency        (b) Guide wavelength

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2. What are the advantages and disadvantages of microwave frequencies?
3. Write the properties of scattering matrix.
4. Define the terms: (a) Directivity        (b) Power gain
5. List different types of microwave resonators.
6. Explain the terms: (a) Isolator        (b) Circulator

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7. What are the limitations of conventional tubes at microwave frequencies?
8. Mention the advantages of parametric amplifiers.
9. What are the advantages and disadvantages of using microwave frequencies in communication systems?
10. Write a short note on microwave hazards.

Part-B (5 x 10 = 50 Marks)

1. (a) Explain the propagation of TE waves in a rectangular waveguide.
   

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   (b) A rectangular waveguide with dimensions a = 2.5 cm and b = 1 cm is used to transmit
   TE10 mode at 10 GHz. Determine the cut-off frequency, guide wavelength, and wave impedance.
2. (a) Derive the scattering matrix for a lossless reciprocal three-port network.
   (b) Explain how impedance matching is achieved with quarter wave transformer.
3. (a) With the help of neat diagram explain the working of Magic Tee.
   

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   (b) Write short notes on cavity resonators.
4. (a) Explain the working principle of two-cavity Klystron amplifier with neat sketch.
   (b) A helix traveling-wave tube operates at 10 GHz with a beam voltage of 3 kV and a beam current of 30 mA. If the helix impedance is 10 ohms and the circuit length is 50 cm, find the gain parameter and the output power gain in decibels.
5. (a) Explain the principle of operation of Gunn diode.
   (b) Write short notes on PIN diode.

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6. (a) Draw the block diagram of a microwave bench and explain the function of each component.
   (b) Explain the measurement of power at microwave frequencies.
7. Write short notes on any two of the following:
   (a) Microwave applications in Radar
   (b) Microwave ovens
   

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   (c) Satellite Communication

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