Microwave Engineering Sem 7 EXTC MU Question Paper Nov 2021

Q1] Multiple Choice Questions (MCQ). All the Questions are compulsory and carry equal marks: 20 Marks

1) The value of VSWR for matched termination is _____

a) 1

b) 0

c) 5

d) -1

2) For conventional vaccume tubes the gain bandwidth product __________.

a) Increases with frequency

b) Is constant

c) Decreases with gain

d) Depends upon type of tube

3) Zero mode is not preferred in magnetron because _______

a) Of low efficiency

b) Of high noise

c) Less number of cavities

d) Zero power output

4) The material that exhibits transferred electon effect is _____

a) Silicon

b) Germanium

c) Indium Phosphide

d) Copper

5) Impedance matching is done in order to ______

a) Reduce VSWR

b) Increase reflection

c) Make characteristic impedance rise

d) Rotate smith chart by 90 degrees

6) The two methods to measure microwave power are ______

a) Bolometer and Calorimeter

b) Capacitor and Calorimeter

c) Bolometer and Capacitor

d) Slotted line and Inductor

7) Helix is preferred slow wave structure because ________

a) Of high wattage

b) Of low dispersion

c) Of high elasticity

d) Zero bandwidth

8) In two cavity klystron the negative feedback occurs due to _______

a) Glass envelope

b) Linear beam structure

c) Velocity Modulation

d) Electron beam movement

9) Microstrip line has its characteristic impedance depending on ______

a) Relative dielectric constant, width of strip, thickness of strip

b) Type of metal used

c) Voltage across conductors

d) Types of connectors

10) Which of the following materials are generally preferred for waveguide?

a) Cast Iron and steel

b) Non metallic solids including plastic

c) High carbon steel and Vanadium steel

d) Brass and Aluminium

Q2] Solve any Four out of Six : 5 marks each

A) The gain equation of travelling wave tube is A^p = -9.54 + 47.1 NC dB.
Explain why term -9.54 appears in this equation.

B) What is importance of beam coupling coefficient in reflex klystron.

C) What is important of χ/8, 3χ/8, 5χ/8 in double stub matching.

D) Explain use of reentrant cavity in microwave engineering.

E) Explain Faraday rotation in ferrites.

F) What is main purpose of slotted section with line carriage.

Q3] Solve any Two out of Three : 10 marks each

A) What are scattering paameters. Why are these preferred to Z, Y, ABCD and H parameters at microwave frequency range. Explain scattering parameters for two port network.

B) Compare HMIC and MMIC with neat diagrams.

C) What is meant by negative resistance at microwave frequencies. Explain how negative resistance is achieved in TRAPATT diode.

Q4]

A) Solve any Two: 5 marks each

i. Explain two valley model theory of Gunn diode.

ii. Why a parametric amplifier low noise amplifier? Explain working of parametric up converter

iii. Why TEM mode can not propagate in hollow metallic waveguides.

B) Solve any One: 10 marks each

i. Explain measurement of VSWR of unknown load using microwave test bench set up block diagram.

ii. Explain working of four port circulator using magic tee and gyrator.