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Microwave Communication
Quiz 3
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Q.1
It is possible to increase the maximum range of a radar equipment by
Lowering the pulse frequency
Raising the peak power of the transmitter
Narrowing the beam width and increasing the pulse duration
All of these
Q.2
A high-power microwave pulse of the order of megawatts can be generated by a
Traveling-wave tube
Magnetron
Reflex klystron
Gunn diode
Q.3
In a pulsed radar set, the STC circuit is used to
Improve the target bearing resolution
Increases receiver sensitivity for echoes from targets
Vary the pulse frequency in order to control the maximum target
Reduce interference from the effects of sea return
Q.4
Which causes multipath or frequency selective fading?
Small reflector
Nearer reflector
Further reflector
Large reflector
Q.5
If k-factor is greater than 1, the array beam is bent
Away from the earth
Towards the ionosphere,
Towards the earth
Towards the outer space
Q.6
___________ is a microwave device in which the frequency of operation is determined by the biasing field strength.
vtm
gyratron
helix bwo
none of the mentioned
Q.7
In a___________ oscillator, the RF wave travels along the helix from the collector towards the electron gun.
interaction oscillator
backward wave oscillator
magnetrons
none o the mentioned
Q.8
___________ is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity.
backward wave oscillator
reflex klystron
travelling wave tube
magnetrons
Q.9
To prevent an IMPATT diode from burning, a constant bias source is used to maintain__________ at safe limit.
average current
average voltage
average bias voltage
average resistance
Q.10
A class B amplifier consists of___________ transistors in order to conduct the input signal over the entire cycle.
1
2
4
6
Q.11
______________amplifiers are linear circuits, where the transistor is biased to conduct over the entire range of the input signal cycle.
class a amplifiers
class b amplifiers
class c amplifiers
none of the mentioned
Q.12
In transistor oscillators, FET and BJT are used. Instability is achieved by:
giving a negative feedback
giving a positive feedback
using a tank circuit
none of the mentioned
Q.13
In transistor oscillators, the requirement of a negative resistance device is satisfied using a varactor diode.
true
false
Q.14
To achieve stable oscillation, Zin + ZL=0 is the only necessary and sufficient condition to be satisfied by the microwave oscillator.
true
false
Q.15
For achieving steady state oscillation, the condition to be satisfied in terms of reflection coefficients is:
Гin=Гl
Гin=-Гl
Гin=1/Гl
none of the mentioned
Q.16
In a microwave oscillator, a load of 50+is connected across a negative resistance device of impedance -50-50j. Steady state oscillation is not achieved in the oscillator.
true
false
Q.17
Any device with negative impedance as its characteristic property can be called:
energy source
energy sink
oscillator
none of the mentioned
Q.18
The equivalent circuit of a quartz crystal has LCR arm capacitance of 12nF and inductance of 3mH and parallel arm capacitance of 4nF. Parallel resonant frequency for the circuit is:
3 mhz
0.3 mhz
6 mhz
9 mhz
Q.19
Parallel resonant frequency of quartz crystal is given by:
1/ √(lcₒc/(cₒ+c))
1/√lc
1/√lcₒ
1/ √(l(cₒ+c) )
Q.20
In the equivalent circuit of a quartz crystal, LCR arm has an inductance of 4 mH and capacitor has a value of 4nF, then the series resonant frequency of the oscillator is:
0.25 mhz
2.5 mhz
25 mhz
5 mhz
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