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Free download in PDF Microwave Communication General Knowledge Objective Type Questions & Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(21)
As the electron beam moves through a klystron’s intercavity drift space
[A]
Frequency modulation at the input cavity creates velocity modulation at the output cavity
[B]
Velocity modulation at the input cavity creates density modulation at the output cavity
[C]
Density modulation at the input cavity creates velocity modulation at the output cavity
[D]
Phase modulation at the input cavity creates velocity modulation at the output cavity.
Answer: Velocity modulation at the input cavity creates density modulation at the output cavity
(22)
The frequency of the oscillation generated by a magnetron, is mainly determined by
[A]
The flux density of the external magnet
[B]
The ratio of the dc cathode voltage to the magnetic flux density
[C]
The number of the cavity resonators
[D]
The dimension of each cavity resonator
Answer: The dimension of each cavity resonator
(23)
If the instantaneous RF potentials on the two sides of a magnetron cavity are of opposite polarity, the operation is in the
[A]
π mode
[B]
π/2 mode
[C]
2π mode
[D]
π/4 mode
(24)
The Gunn diode oscillator
[A]
Depends on the formation of charge domain
[B]
Operates over a positive resistance characteristic
[C]
Is capable of generating continuous microwave power of the order of kilowatt
[D]
Generates frequencies which are below 100 MHz
Answer: Depends on the formation of charge domain
(25)
What ferrite device can be used instead of duplexer of isolate microwave transmitter and receiver when both are connected to the same antenna?
[A]
Isolator
[B]
Magnetron
[C]
Simplex
[D]
Circulator
(26)
To achieve good bearing resolution when using a pulsed-radar set, an important requirement is
[A]
A narrow, antenna-beam width in the vertical plane
[B]
A narrow, antenna-beam width in the horizontal plane
[C]
A low repetition rate
[D]
A high duty cycle
Answer: A narrow, antenna-beam width in the horizontal plane
(27)
When used in conjunction with a radar set, the purpose of an echo box is to provide an artificial target.
[A]
Which may be used to tune the radar synchronizer
[B]
Which may be used to tune the radar receiver
[C]
To the tone of the pulse repetition
[D]
Tune the magnetron to the correct frequency
Answer: Which may be used to tune the radar receiver
(28)
In a radar-set receiver, the usual mixer stage is
[A]
And FET
[B]
A tunnel diode
[C]
A silicon crystal
[D]
A Rochelle salts crystal
Answer: A silicon crystal
(29)
Klystron oscillators are most often used in the frequency range of
[A]
300 to 3000 MHz
[B]
3000 to 30000 MHz
[C]
30 to 30000 MHz
[D]
10 to 10000 MHz
Answer: 3000 to 30000 MHz
(30)
Oscillators of a klystron tube are maintained
[A]
By bunches of electrons passing the cavity grids
[B]
By plate-to-cathode feedback
[C]
By feedback between the accelerating grid and the repeller
[D]
By circulating bunches of electrons within the cavities.
Answer: By bunches of electrons passing the cavity grids
31
What allow microwave to pass in only one direction?
[A]
RF emitter
[B]
Capacitor
[C]
Varactor-triac
[D]
Ferrite emitter
32
In an SHF pulsed radar set, a reflex klystron can be used as a
[A]
Single mixer stage
[B]
Local oscillator
[C]
Transmitter oscillator
[D]
Duplexer stage
33
A Class-S Emergency Position-Indicating Radio Beacon (E.P.I.R.B)
[A]
Must be capable of floating or being secured to a survival
[B]
Must have its battery replaced after emergency use
[C]
May be tested during the first five minutes of any hour
[D]
All of these
34
A PPI cathode-ray tube as used on a radar set
[A]
Is used to check the percentage of modulation
[B]
Indicates both the range and azimuth of a target
[C]
Indicates only the range of a target
[D]
Is used for receiver alignment
Answer: Is used for receiver alignment
35
The resonant frequency of a cavity resonator depends upon
[A]
The mode of operation
[B]
Its electrical dimensions
[C]
Its physical dimensions
[D]
The capacitor which tunes it
Answer: Its physical dimensions
36
The maximum usable range of the usual radar set (on any particular range setting) is determined by
[A]
The width of the transmitted pulses
[B]
The interval between transmitted pulses
[C]
The bandwidth of the receiver IF stages
[D]
The duty cycle
Answer: The interval between transmitted pulses
37
A reflex klystron is oscillating at the frequency of its resonant cavity. If the reflector voltage is made slightly less negative, the
[A]
Oscillation will cease
[B]
Output power would increase
[C]
The frequency will decrease
[D]
Bunching would occur earlier in time
Answer: The frequency will decrease
38
The coarse frequency adjustment of a reflex klystron is accomplished by
[A]
The AFC system
[B]
Adjusting the flexible wall of the resonant cavity
[C]
An adjustment in the synchronizer
[D]
Varying the repeller voltage
Answer: Adjusting the flexible wall of the resonant cavity
39
In a pulsed radar set, the STC circuit is used to
[A]
Improve the target bearing resolution
[B]
Increases receiver sensitivity for echoes from targets
[C]
Vary the pulse frequency in order to control the maximum target
[D]
Reduce interference from the effects of sea return
Answer: Reduce interference from the effects of sea return
40
In a pulsed radar set, the function of the duplexer is to
[A]
Aid in calibrating the display unit
[B]
Prevent frequency drift in the klystron
[C]
Allow the transmitter and the receiver to operate from a common antenna
[D]
All of these
Answer: Allow the transmitter and the receiver to operate from a common antenna
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