Download AKTU B-Tech 6th Sem 2018-2019 REC 601 Microwave Engineering Question Paper

REC601

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Paper ID: 131299

B.TECH.

Sub Code: REC 601

(SEM-VI) THEORY EXAMINATION 2018-19

MICROWAVE ENGINEERING

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Time: 3 Hours

Total Marks: 70

Note: 1. Attempt all Sections. If require any missing data; then choose suitably.

SECTION A

1. Attempt all questions in brief. 2 x 7 = 14

1. Differentiate dominant and degenerative mode in waveguide.

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2. Write any two properties of E-plane tee microwave device.
3. Define cut-off wave number (kc). Show that kc² = ?² µ e for loss less dielectric.
4. Define insertion loss?
5. What are the applications of reflex klystron?
6. How is microwave solid state device different from low frequency devices?

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7. State the differences between TWT and klystron.

SECTION B

2. Attempt any three of the following: 7 x 3 = 21

1. Explain the working principle of IMPATT diode. How does the electric field and hole concentrations varies with the input ac signal.
2. What is electron transfer mechanism? Explain the operation and working of Gunn diode.
3. What is directional coupler? What are the different types of directional coupler? Explain the working principle of 2-hole directional coupler. Also determine its S-matrix

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4. Explain the construction, working and application of microwave isolators.
5. What do you mean by E-plane tee and H-plane tee? Compare their properties.

SECTION C

Attempt any one part of the following: 7x1=7

3.

1. A TE₁₁ mode is propagating through a circular waveguide. The waveguide is air filled and has a diameter of 12 cm. Calculate: (Given X'₁₁=1.841) (i) Cut off frequency (ii) Guide wavelength for the frequency of 2.5GHz (iii) Wave impedance at 2.5 GHz

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2. Why is Magnetron called cross field device? What is meant by p mode operation in Magnetron containing eight cavity resonators? Describe how strapping separates the p mode from other possible modes.

4. Attempt any one part of the following: 7x1=7

1. Explain Gunn Effect with respect to two valley model. Draw the graph between applied electric field and current density across Gunn diode.
2. A rectangular cavity resonator has dimension a=7.5cm, b=4cm and c=16 cm. calculate cut-off wave number and phase constant.

5. Attempt any one part of the following: 7x1=7

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1. Classify different types of microwave amplifiers and oscillators. Discuss Working principle of avalanche transit time devices.
2. What is circulator? Discuss its theory of operation and suggest its applications.

6. Attempt any one part of the following: 7x1=7

1. With the help of functional diagram, explain the working principle of two cavity Klystron amplifier. Calculate optimum length of drift space, maximum efficiency, and voltage gain.
2. What are the various methods for measuring frequency? Discuss them in details.

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7. Attempt any one part of the following: 7x1=7

1. Show that the TM₀₁ and TM₁₀ modes in rectangular waveguide do not exist.
2. Discuss method to measure impedance of load. Indicate the use of smith chart in this measurement.

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