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Worksheets6th sem 3/6/21
Total questions: 20
Worksheet time: 10mins
1) The velocity factor of a transmission line depends on
Temperature
skin effect
relative permittivity of dielectric
none of the above
2)A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0 value. VSWR is
10
2
1
infinity
3)In a klystron amplifier the input cavity is called
buncher
catcher
Pierce gun
collector
4)The features of a multicavity klystron are
Frequency range - 0.25 GHz to 100 GHz
Power output - 10 kW to several hundred kW
Power gain - 60 dB (nominal value)
Efficiency - about 40%.
5)The reflection coefficient on a line is 0.2 ∠45°. The SWR is
0.8
1.1
1.2
1.5
6)Microwave resonators are used in
microwave oscillators
microwave narrow band amplifier
microwave frequency metres
all of the above
7)In a TWT the amplitude of resultant wave travelling down the helix
increases exponentially
increases linearly
decreases exponentially
is almost constant
8)Both Impatt and Trapatt devices use avalanche effect
TRUE
FALSE
9) In a directional coupler
isolation (dB) equals coupling plus directivity
coupling (dB) equals isolation plus directivity
directivity (dB) equals isolation plus coupling
isolation (dB) equals (coupling) (directivity)
10)As the frequency is increased, the charging MVAR in a cable
decreases
increases
remain the same
decreases or remains the scheme
11) In a three cavity klystron amplifier, the oscillations are excited in
input cavity
output cavity
intermediate cavity
both (a) and (b)
12)Which of the following lines is non-radiating?
Open two wire
Coaxial
Both A and B
none of the above
13)Which of the following devices uses a helix?
Klystron amplifier
Klystron Oscillator
TWT
Both A and B
14) Which of the following parameters is negligible in transmission lines?
R
L
C
G
15) Impedance level of Impatt diodes is generally lower than that of Gunn diodes
TRUE
FALSE
16) In a circular waveguide the dominant mode is
TE01
TE11
TE21
TE10
17) S parameters are expressed as a ratio of
Voltage and current
Impedance at different ports
Indecent and the reflected voltage waves
None of the mentioned
18) The device used to get the measurement of S parameters of n- port micro wave network is
CRO
Network analyzer
Circulator
Attenuator
19) Scattering matrix for a reciprocal network is
Symmetric
Unitary
Skew symmetric
Identity matrix
20) The relation between voltage, current and admittance matrices of a microwave network is
[I] = [Y] [V].
[Y] = [V] [I].
[I] = [Z] [V].
[V] = [Z]-1[I].
