M.Sc.(Electronics) (Semester (CBCS) Examination, 2017
MICROWAVE DEVICES, ANTENNAS AND MEASUREMENTS
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Day Date: Wednesday, 19-04-2017 Max. Marks: 70
Time: 02.30 PM to 05.30 PM
N.B. Answer Five Questions.
Question 1 and 2 are compulsory.
Figures to the right indicate full marks.
Attempt any Three from Q.3 to Q.7.
Q.1 Choose correct answer: 08
The reflection coefficient on a line is 0.2 .The SWR

0.8 1.1 1.2 1.5
2 Because of its axial symmetry, the conical horn can handle
any polarization of the dominant mode.
TM10 TM01 TE11 TM11
3 For fixed antenna size, the focusing ability improves as the

Constant Decreases
Increase None of above
4 The dominant mode in a particular guide is the mode

Lowest cutoff frequency
Highest cutoff frequency
Highest cutoff wavelength
Lowest or Highest cutoff frequency
5 A frequency at which microwave ovens operate is
50 Hz 4.5 GHz
3.3 GHz 2.45 GHz
6 A circularly polarized wave has dB ellipticity since
Emax Emin
5 30 0 20
7 Velocity factor of transmission line depends
Temperature Relative Permittivity of dielectric
Skin effect None of the above
8 The horn is usually used as a standard gain
antenna.
Page 2 of 2
Pyramidal Sectoral E-plane
Sectoral H-plane Sectoral H-plane or sectoral E-plane
State weather true or false 06
The electronic efficiency of the klystron amplifier is defined as
the ratio of the output power to the input power.
For a fixed antenna size, the focusing ability improves as the
wavelength Decreases
GaAs exhibits transferred electron effect.
The current sensitivity of the detector is the ratio of rectified
current to the absorbed r-f-power.
A flat line is resonant.
1 watt equals +30dbm
Q.2 Write short answers (Any Two) 10
Describe Reflections at Conducting Boundaries.
What is impedance matching? Explain various methods of
achieving impedance matching.
Write a detail note on Rat-Race Circuits.
What are the major differences between the TWT and the
klystron?
Q.3 Explain the process of velocity modulation and bunching a reflex
klystron oscillator with the help of applegate diagram.
08
Write a note on Gunn effect diodes for microwave generators and
amplifications
06
Q.4 Derive the expression for the characteristics equation of two wire
transmission line.
08
A transmission line has the following parameters 06
R=2 G=0.5 m f=1GHz L=8nH/m c=0.23pF
Q.5 Show that TEM wave cannot propagate in waveguide by making
use of Maxwell's equation.
08
Explain operation of E-H plane Tee junction and derive the
scattering matrix of it.
06
Q.6 Explain Wave propagation in Imperfect Insulators. 08
With schematic diagrams explain Wave Polarization. 06
Q.7 Obtain the equations for 08
i. Attenuation constant
ii. Phase constant
iii. Characteristic impedance and
iv. Phase velocity for a transmission line at microwave
frequencies
Discuss the use of crystals as low-level detectors. 06