MCQ SOLUTIONS FOR MAINTENANCE OF RADIO & COMMUNICATION SYSTEMS (AeSI)
FOLLOWING ARE THE MCQ QUESTIONS THAT ASKED IN MAINTENANCE OF RADIO & COMMUNICATION SYSTEMS PAPER OF AERONAUTICAL SOCIETY OF INDIA EXAM.ANSWERS FOR THESE QUESTIONS ARE GIVEN AT THE END OF EACH QUESTION.IN THIS SUBJECT MCQ TYPE QUESTIONS ARE ASKED FROM JUNE 2015,SO I HAVE ANSWERED THREE QUESTION PAPERS(UP TO DATE) THAT INCLUDE SESSIONS JUNE 2015,DECEMBER 2015 AND JUNE 2016.
ALSO THESE QUESTIONS CAN ASKED IN PSU EXAMS AND IN OTHER ENGINEERING UNIVERSITY EXAMS WHICH COVER THE TOPICS MICROWAVE,RADIO COMMUNICATION,MICROWAVE DEVICES,ANTENNAS,RADIO WAVES ETC.
1.The dominant mode in rectangular wave guide is
(a) TM10 (b) TE10 (c) TE11 (d) TM01
ANSWER:TE10
2.Radar antennas are usually horn antennas
(a) Horn antennas (b) log periodic antennas
(c) parabolic reflectors (d) frequency independent antennas
ANSWER:PARABOLIC REFLECTORS
3.The device not used for pulse operation is
(a) BFO (b) TWT (c) Multicavity klystron (d) Magnetron
ANSWER:BFO
4.The wave guides are generally used above
(a) 100 MHz (b) 3GHz (c) 88 MHz (d) 3 MHz
ANSWER: 3 GHZ
5.The glass tube of TWT(travelling wave tube) may be coated with aquadag to
(a) Provide attenuation (b) Improve bunching
(c) Increase gain (d) Help Focussion
ANSWER:PROVIDE ATTENUATION
6. A lossless antenna has a directive gain of +6dB.If 1mW of power is fed to it,the total power is fed to it,the total radiated will be
(a) 7 mW (B) 1 mW (c) 4 mW (d) 0.25 mW
ANSWER: 4 mW
7.Microwave link repeaters are typically 50 Km apart because
(a) of atmospheric attenuation
(b) of earths curvature
(c) of limitation of transmitted power
(d) to ensure that applied dc voltage is not excessive
ANSWER: OF EARTHS CURVATURE
8. UHF and Microwave frequencies in the range 0.3 GHz TO 30 GHz can be best transmitted using
(a) Surface propagation
(b) Duct propagation
(c) ground wave propagation
(d) Sky wave propagation
ANSWER:DUCT PROPAGATION
9. A Parametric amplifier has input and output frequency of 2.25 GHz and is pumped at 4.75 GHz .
It is a
(a) Degenerate amplifier
(b) travelling amplifier
(c) Lower side band up converter
(d) upper side band up converter
ANSWER: DEGENERATIVE AMPLIFIER
10. If the length of antenna is increased,the directive gain
(a) increases (b) decreases
(c) remains same (d) becomes infinite
ANSWER: INCREASES
11.The dominant modes in rectangular and cylindrical wave guide is
(a) TE10 & TE11
(b) TE10 & TM10
(c) TE11 & TE10
(d) TE10 & TM11
ANSWER: TE10 & TE11
12. A microwave tube amplifier uses an axial magnetic field and radial electric field.This tube represents:
(a) Reflex klystron
(b) TWT
(C) Magnetron
(d) CFA
ANSWER: CFA
13. In a radar system,if the antenna diameter is increased by a factor of 4,the minimum detectable range will be increased by a factor of
(a) 2 root 3
(b) 4
(c) 3
(d) 3 root 2
ANSWER: 4
14. One of the following is very useful as a multi band HF receiving antenna. This represents
(a) Conical Horn (b) folded dipole
(c) log periodic (d) square loop
ANSWER: LOG PERIODIC
15. For a parabolic reflector antenna,the beam width is given by
(a) 70^/D
(b) 170 D/^
(c) 30^D
(D) D/(30^)
ANSWER: 70^/D
NOTE:HERE ^ MEANS LAMDA
16. A TWT is sometimes preferred to a Magnetron as a radar transmitter output tube since it is
(a) Capable of a larger duty cycle
(b) less noisy
(c) a more efficient amplifier
(d) more broad band
ANSWER: CAPABLE OF LARGER DUTY CYCLE
17. Antenna radiation efficiency can be increased by
(a) providing effective earthing
(b) increasing radiation resistance
(c) reducing radiation resistance
(d) increasing effective length
ANSWER: INCREASING RADIATION RESISTANCE
18.The device not used for pulse operation is
(a) BWO
(b) TWT
(c) Multicavity Klystron
(d) Magnetron
ANSWER:BWO
19. Top loading is sometimes used with antenna in order to increase its
(a) beam width
(b) band width
(c) input capacitance
(d) effective height
ANSWER: EFFECTIVE HEIGHT
20.The dominant mode in cylindrical wave guide is
(a) TE10
(B) TE11
(C) TM10
(D) TM11
ANSWER: TE11
ALSO THESE QUESTIONS CAN ASKED IN PSU EXAMS AND IN OTHER ENGINEERING UNIVERSITY EXAMS WHICH COVER THE TOPICS MICROWAVE,RADIO COMMUNICATION,MICROWAVE DEVICES,ANTENNAS,RADIO WAVES ETC.
1.The dominant mode in rectangular wave guide is
(a) TM10 (b) TE10 (c) TE11 (d) TM01
ANSWER:TE10
2.Radar antennas are usually horn antennas
(a) Horn antennas (b) log periodic antennas
(c) parabolic reflectors (d) frequency independent antennas
ANSWER:PARABOLIC REFLECTORS
3.The device not used for pulse operation is
(a) BFO (b) TWT (c) Multicavity klystron (d) Magnetron
ANSWER:BFO
4.The wave guides are generally used above
(a) 100 MHz (b) 3GHz (c) 88 MHz (d) 3 MHz
ANSWER: 3 GHZ
5.The glass tube of TWT(travelling wave tube) may be coated with aquadag to
(a) Provide attenuation (b) Improve bunching
(c) Increase gain (d) Help Focussion
ANSWER:PROVIDE ATTENUATION
6. A lossless antenna has a directive gain of +6dB.If 1mW of power is fed to it,the total power is fed to it,the total radiated will be
(a) 7 mW (B) 1 mW (c) 4 mW (d) 0.25 mW
ANSWER: 4 mW
7.Microwave link repeaters are typically 50 Km apart because
(a) of atmospheric attenuation
(b) of earths curvature
(c) of limitation of transmitted power
(d) to ensure that applied dc voltage is not excessive
ANSWER: OF EARTHS CURVATURE
8. UHF and Microwave frequencies in the range 0.3 GHz TO 30 GHz can be best transmitted using
(a) Surface propagation
(b) Duct propagation
(c) ground wave propagation
(d) Sky wave propagation
ANSWER:DUCT PROPAGATION
9. A Parametric amplifier has input and output frequency of 2.25 GHz and is pumped at 4.75 GHz .
It is a
(a) Degenerate amplifier
(b) travelling amplifier
(c) Lower side band up converter
(d) upper side band up converter
ANSWER: DEGENERATIVE AMPLIFIER
10. If the length of antenna is increased,the directive gain
(a) increases (b) decreases
(c) remains same (d) becomes infinite
ANSWER: INCREASES
11.The dominant modes in rectangular and cylindrical wave guide is
(a) TE10 & TE11
(b) TE10 & TM10
(c) TE11 & TE10
(d) TE10 & TM11
ANSWER: TE10 & TE11
12. A microwave tube amplifier uses an axial magnetic field and radial electric field.This tube represents:
(a) Reflex klystron
(b) TWT
(C) Magnetron
(d) CFA
ANSWER: CFA
13. In a radar system,if the antenna diameter is increased by a factor of 4,the minimum detectable range will be increased by a factor of
(a) 2 root 3
(b) 4
(c) 3
(d) 3 root 2
ANSWER: 4
14. One of the following is very useful as a multi band HF receiving antenna. This represents
(a) Conical Horn (b) folded dipole
(c) log periodic (d) square loop
ANSWER: LOG PERIODIC
15. For a parabolic reflector antenna,the beam width is given by
(a) 70^/D
(b) 170 D/^
(c) 30^D
(D) D/(30^)
ANSWER: 70^/D
NOTE:HERE ^ MEANS LAMDA
16. A TWT is sometimes preferred to a Magnetron as a radar transmitter output tube since it is
(a) Capable of a larger duty cycle
(b) less noisy
(c) a more efficient amplifier
(d) more broad band
ANSWER: CAPABLE OF LARGER DUTY CYCLE
17. Antenna radiation efficiency can be increased by
(a) providing effective earthing
(b) increasing radiation resistance
(c) reducing radiation resistance
(d) increasing effective length
ANSWER: INCREASING RADIATION RESISTANCE
18.The device not used for pulse operation is
(a) BWO
(b) TWT
(c) Multicavity Klystron
(d) Magnetron
ANSWER:BWO
19. Top loading is sometimes used with antenna in order to increase its
(a) beam width
(b) band width
(c) input capacitance
(d) effective height
ANSWER: EFFECTIVE HEIGHT
20.The dominant mode in cylindrical wave guide is
(a) TE10
(B) TE11
(C) TM10
(D) TM11
ANSWER: TE11
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