JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV MICROWAVE AND OPTICAL COMMUNICATIONS Previous Question Paper (January/February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What are the limitations of conventional vacuum tubes?
Answer
Conventional vacuum tubes suffer from transit time effects, where the time taken by electrons to travel between electrodes becomes comparable to the period of the microwave signal, and lead inductance/capacitance effects, which cause significant impedance mismatch and power loss at high frequencies.
How the two cavity Klystron acts as an oscillator?
Answer
A two-cavity Klystron acts as an oscillator when a portion of the output power from the catcher cavity is fed back to the buncher cavity in the correct phase. This positive feedback sustains oscillations at the resonant frequency of the cavities.
What is meant by Hull Cutoff Voltage?
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How a Gunn Diode act as an oscillator?
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What is the principle of microwave phase shifter?
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Discuss about waveguide discontinuities?
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Give the properties of S matrix.
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Discuss the significance of slotted section.
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What is a graded index fiber? Sketch its refractive index profile.
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Discuss about “Signal Distortion” in fibres.
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Part B
Explain in detail about the classification of M type Microwave tubes.
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Explain the velocity modulation in two cavity Klystron amplifiers.
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Draw the diagram of TWT and explain the operation in detail.
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Explain the significance of Applegate diagram.
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Explain the growth of oscillations in a travelling wave magnetron.
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Discuss about magnetron and its types.
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Write short notes on “TRAPATT diode”.
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What are the different avalanche transit time devices?
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Discuss in detail about Ferrites Composition and Characteristics.
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Explain about various wave guide attenuators.
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Draw the structure diagram of H-plane Tee and explain its characteristics.
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Explain the principle of Faraday rotation.
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Explain the operation of Directional Coupler with a neat diagram and derive its Scattering Matrix.
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Describe how a magic tee can be used in constructing a Circulator and a Duplexer.
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With the help of a neat sketch, briefly explain the functions of different blocks of a microwave bench.
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Discuss in detail about measurement of VSWR.
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Explain Classification of Optical Fibers.
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Explain LED Structure with neat sketch.
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Describe any two types of Losses in Optical Fiber Communication System.
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Describe in detail about Rise time Budget of Optical Fibre Communication interms of digital system design.
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