M.Sc. (Semester IV) (CBCS) Examination Nov/Dec-2018
Electronics
MICROWAVE DEVICES, ANTENNAS AND MEASUREMENTS
Time: 2½ hrs Max. Marks: 70
Instructions: Attempt five questions.
Q.1 and 2 are compulsory.
Answer any three questions from Q.3 to Q.7
Figures to the right indicate full marks.
Q.1 Choose the alternatives given below. 08
Velocity factor of transmission line depends on
Temperature Relative Permittivity of dielectric
Skin effect None of the above
In lossless line RL Z0 then
Reflection coefficient is 0
Reflection coefficient is ∞
Reflection coefficient is negative
Reflection coefficient is positive
In a loss less line the propagation constant is equal to


A frequency at which microwave ovens operate is
50 μHz 2.45 GHz
3.3 GHz 4.5GHz
The antenna most commonly used for TV broadcasting in the UHF band
is
Dipole antenna Turnstile antenna
Yagi antenna Rhombic antenna
For low power FM wave is used.
Reflex klystron TWT
Two Cavity Klystron MASER
Which one of the following is correct?
In mode operation of magnetron, the spokes due to phase focusing
effect rotate at an angular velocity corresponding to
One pole cycle Two pole cycle
Four poles cycle Six poles cycle
State True or false. 06
For measurement of high VSWR double minimum method is relevant.
In hallow rectangular waveguide, the phase velocity Increases with
increasing frequency.
Travelling wave tube can be used for amplification of microwave energy?
For frequency multiplications two cavity Klystron is used.
A lossless line of characteristics impedance Z0 is terminated in pure
reactance of -jZ0 value, VSWR is 1.
In microwave power measurement using bolometers, the principles of
working is the variation of resistance with absorption of power.
Q.2 Write short answers (Any Two) 10
Explain the action of rat-race junction.
What is directional coupler? Describe various types of directional coupler.
Mention the typical applications of Microwaves.
Explain the fundamental difference between Waveguide and TEDs? 04
Q.3 Briefly explain RWH theory. 08
Discuss the radiation form microstrip antennas. What are the limitations of
microstrip antennas?
06
Q.4 What do you mean by microwave measurements? Describe double minima
method for power measurement.
08
Explain Horn antenna in detail. 06
Q.5 Explain a reflex klystron oscillator with the help of applegate diagram. 08
Explain briefly 06
Reflection coefficient
Transmission coefficient
Q.6 A transmission line has a characteristic impedance of 50 j0.01 Ω and is
terminated in a load impedance of 73 − j42.5 Ω. Calculate the reflection
coefficient and the standing wave ratio.
08
Write a note on crystal rectifier? 06
Q.7 Explain briefly cylindrical magnetron? What do understand by 08
What do you mean by Rectangular-Cavity Resonator? Explain Q Factor of a
Cavity Resonator.