M.Sc. (Semester IV) (CBCS) Examination Mar/Apr-2018
Electronics
MICROWAVE DEVICES, ANTENNAS AND MEASUREMENTS
Time: 2 ½ hrs
Max. Marks: 70
Instructions: Attempt five questions. Q. and 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
The correct sequence of frequency bands in order of increasing available peak power is
C -band, X -band, L -band, S -band
X -band, C -band, S -band, L -band
X -band, S -band, C -band, L -band
S -band, X -band, C -band, L -band
Which one of the following is correct?
∇ × j
∇ × j ∂ρ2∂t2=0
∇ .j
∇ .j ∂ρ2∂t2=0
The input impedance of short circuited lossless line of length less than a quarter wavelength is
purely resistive
purely inductive
purely capacitive
complex
In hallow rectangular waveguide, the phase velocity
increases with increasing frequency
decreases with increasing frequency
is independent of frequency
will vary with frequency depending upon the frequency range
Rectangular wave guide will not be supported modes of transmission.
TE10
TE11
TM11
TM10
In lossless line RL Z0 then
Reflection coefficient is 0
Reflection coefficient is ∞
Reflection coefficient is negative
Reflection coefficient is positive
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
The reflection coefficient on a line is 0.2 450. The SWR is
0.8
1.1
1.5
1.2
State True or false.
06
Dipole antenna is most commonly used for TV broadcasting in the UHF band.
The presence of slot on the waveguide doesn't change the boundary conditions.
Displacement current only exists when the electric field is time-varying.
Slow-wave structures are special circuits that are used in microwave tubes to reduce the wave velocity in a certain direction.
IMPATT diode is transferred electron device?
In microwave power measurement using bolometers, the principle of working is the variation of resistance with absorption of power.
Q.2
Attempt any two.
10
What is impedance matching? Explain various methods of achieving impedance matching?
Write a detail note on corners, bends and twists of waveguide.
Write a note on microwave frequency spectrum.
Explain the fundamental difference between Waveguide and TEDs?
04
Q.3
Explain the process of velocity modulation and bunching a reflect klystron oscillator with the help of applegate diagram.
08
Derive Maxwell's equations in derivative and integral form.
06
Q.4
A transmission line has the following parameters.
R 2 Ω/m G 0.5 f 1GHz L 8nH/m c 0.23pF Calculate:1) the characteristics impedance; the propagation constant
08
Explain the double minimum method of measurement of VSWR.
06
Q.5
Explain operation of E-H plane Tee junction and derive the scattering matrix of it.
08
Explain Horn antenna in detail.
06
Q.6
What is directional coupler? Describe various types of directional coupler.
08
Explain briefly Reflection coefficient
Transmission coefficient
06
Q.7
Briefly explain RWH theory.
08
With schematic diagrams, explain Wave Polarization.
06