M.Sc. (Semester IV) (CBCS) Examination Nov/Dec-2018
Physics (Applied Electronics)
MICROWAVE DEVICES AND CIRCUITS
Time: 2½ Hours Max. Marks: 70
Instructions: Q.1 and Q.2 is compulsory.
Any three questions from Q.3 to Q.7.
All questions carry equal marks.
Q.1 Choose the correct alternatives:- 06
The term microwave frequencies are generally used for which of the
following frequencies.
1 KHz to 100 KHz 100 KHz to 1 MHz
1 to 300 GHz Above 1 THz
Both E and M fields are purely transverse to the direction of
propagation is called
TE waves TM waves
TEM waves He waves
In Gunn diode, the current density decreases with increase in electric
field is called as
Positive differential resistivity Negative differential resistivity
Differential conductivity None of the above
The reflex Klystron is a
Single cavity Klystron Multi cavity Klystron
Two cavity Klystron None of the above
The characteristic impedance of a rectangular waveguide is,
50 ohms 75 ohms
100 ohms 300 ohms
In a rectangular waveguide, the following waves cannot exist
TEM waves TE waves
TM waves Both TE and TM waves
Q.1 State True or False:- 08
The solution of Maxwell's equation involves three space variables in
addition to the time variable.
The knowledge of planar wave propagation is very important to
understand the propagation of microwaves.
A line termination in its characteristic impedance has a standing wave
ratio of unity.
TWT is used as broad band amplifiers in microwave applications.
The effect of velocity modulation produces bunching of the electron
beam.
The reflex klystron overcomes the disadvantage of the two-cavity
klystron.
A microstrip line is also called as open-strip line.
In waveguides, the lectric and magnetic fields are confined to the space
within the guide only.
Q.2 Write short notes:-
Microwave spectrum
Basic concepts of two-wire line
Matched load
05
05
04
Q.3 Derive the TE mode field equation in a rectangular waveguide.
State the Maxwells's equations in both differential and integral forms.
10
04
Q.4 Draw the relevant diagram explain the construction and functioning of a
reflex Klystron.
Explain the Gunn effect.
10
04
Q.5 Describe the various types of waveguide with necessary equations.
Give a detailed account on waveguide terminations.
10
04
Q.6 Derive equations for losses on coaxial lines 10
Explain the necessity of impedance matching 04
Q.7 With neat diagram, explain the construction and working of waveguide
attenuators.
10
Write a note on standard mismatches. 04