M.Sc. (Semester III) (CBCS) Examination Oct/Nov-2017
Electronic Science
MICROWAVE ELECTRONICS AND APPLICATIONS
Day Date: Saturday, 18-11-2017 Max. Marks: 70
Time: 02.30 PM to 05.00 PM
Instructions: Q.1 and Q.2 are compulsory.
Attempt any three questions from Q. 3 to Q.7.
All questions carry equal marks.
Use of non-programmable calculator is allowed.
Q.1 Select the correct alternative: 06
The cyclotron angular frequency of the circular motion of the electron
is rad/s.
eB/m R/v
evB mv/eB.
TEmn modes in rectangular waveguide are characterized by
Hx 0 Hz 0
Ex 0 Ez 0
Which of the following is avalanche transit-time device?
BARITT IMPATT
TRAPATT All of the above
E-plane tee is also called as a
Series tee H-plane tee
Hybrid tee Directional coupler
Standing wave ratio of transmission line is the ratio of
Minimum voltage to maximum voltage
Maximum voltage to minimum voltage
Maximum current to minimum current
Both b and c
Sinusoidal FM-CW radar is used when, is required.
Range Both range and velocity
Velocity None of above
Q.1 State true and false 08
The lower half of the smith chart represents +jx.
The hybrid ring has characteristics similar to those of hybrid tee.
The device is stable in the gunn oscillation mode of Gunn diode.
Two-cavity klystron is operated by the principles of velocity and current
modulation.
In the over-coupling of resonator loaded Ql factor is equal to half of the
external Qext.
Carriers injected into the drift region are called an IMPATT diode.
Quality factor of micro-strip lines is a ratio of transmitted and incident
power of strip lines.
MODFET is also called a high electron mobility transistor.
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Q.2 Answer the following:- 14
Give a brief account of Gauss law. 05
Explain Two-Hole directional coupler. 05
Write a note on klystron. 04
Q.3 What is transmission coefficient? Obtain and explain with mathematical
expressions.
10
A transmission line has the following parameters: L=8
G=0.5 mmho/m, C=0.23 pF, f=1 GHz. Calculate the characteristic
impedance the propagartion constant.
04
Q.4 Discuss TM modes of rectangular waveguides with cutoff wave number,
cutoff frequency and characteristic wave impedance of TMmn in guide.
07
Explain operation principles of coupled-cavity TWT with suitable diagram. 07
Q.5 Explain TRAPATT diode. What is the Principle of operation in TRAPATT
diode?
10
What is coplanar strip line? 04
Q.6 Distinguish between modulated and un-modulated CW radar. 07
Give a brief account of explanation of linear magnetron. 07
Q.7 Explain electronic motion in an electrical field. 10
An air-filed rectangular waveguide of inside dimensions 7 X 3.5 cm operates
in the dominant TE10 mode.
Find
cutoff frequency
phase velocity of the wave in the guide at a frequency of 3.5 GHz
and guided wavelength