180+ Radiation and Microwave Techniques Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .

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101.	The phase velocity for the TE10 mode in an air filled rectangular waveguide is
A.	less than c
B.	greater than c
C.	equal to c
D.	none of the above
Answer» C. equal to c

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102.	The phase velocity of an electrometric wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is
A.	equal to its group velocity
B.	less than velocity of light in free space
C.	equal to velocity of light in free space
D.	greater than velocity of light in free space
Answer» C. equal to velocity of light in free space

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103.	. Consider an air filled rectangular waveguide with a cross – section of5 cm × 3 cm. For this waveguide, the cut off frequency (in MHz) of TE21mode is
A.	7.81 ghz
B.	9.01 ghz
C.	11.2 ghz
D.	6.89 ghz
Answer» A. 7.81 ghz

discuss

104.	The cut off frequency of waveguide depends upon
A.	the dimensions of the waveguide.
B.	the dielectric property of the medium in the waveguide.
C.	the characteristic impedance of the waveguide
D.	the transverse and axial components of the fields
Answer» A. the dimensions of the waveguide.

discuss

105.	ency for the dominant mode is
A.	2.5 ghz
B.	10 ghz
C.	5 ghz
D.	12.5 ghz
Answer» A. 2.5 ghz

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106.	ency of 30 GHz is (free space impedance 0 =377 Ω)
A.	308 Ω
B.	400 Ω
C.	355 Ω
D.	461 Ω
Answer» B. 400 Ω

discuss

107.	When an electromagnetic waves are propagated in a waveguide
A.	they travel along a broader walls of the guide
B.	they are reflected from the walls but do not travel along them
C.	they travel through the dielectric without touching the walls
D.	they travel along all four walls of the waveguide
Answer» B. they are reflected from the walls but do not travel along them

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108.	Which of the following waveguides tuning components is not easily adjustable?
A.	screw
B.	stub
C.	iris
D.	plunger
Answer» C. iris

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109.	A directional coupler with three or more holes is sometimes used in preference to the two-hole couple
A.	because it is more efficient
B.	to increase coupling of signal
C.	to reduce spurious mode generation
D.	to increase the bandwidth of the system
Answer» C. to reduce spurious mode generation

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110.	A ferrite is
A.	a nonconductive with magnetic properties
B.	an intermetallic compound with particularly good conductivity
C.	an insulator which heavily attenuates magnetic fields
D.	a microwave semiconductor invented by faraday
Answer» A. a nonconductive with magnetic properties

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111.	A PIN diode is
A.	a metal semiconductor point-contact diode
B.	a microwave mixer diode
C.	suitable for use as a microwave switch
D.	often used as a microwave detector
Answer» C. suitable for use as a microwave switch

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112.	A microwave tube amplifier uses an axial magnetic field and a radial electric field. This is the
A.	reflex klystron
B.	coaxial magnetron
C.	travelling wave magnetron
D.	cfa
Answer» B. coaxial magnetron

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113.	Indicate the false statement. Transit time in microwave tubes will be reduced if
A.	the electrodes are brought closer together
B.	a higher anode current is used
C.	multiple or coaxial leads are used
D.	the anode voltage is made larger
Answer» C. multiple or coaxial leads are used

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114.	The multicavity klystron
A.	is not a good low-level amplifier because of noise
B.	has a higher repeller voltage to ensure a rapid transit time
C.	is not suitable for pulsed operation
D.	needs a long transit time through the buncher cavity to ensure current modulation
Answer» A. is not a good low-level amplifier because of noise

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115.	The cavity magnetron uses strapping to
A.	prevent mode jumping
B.	prevent cathode back heating
C.	ensure bunching
D.	improve the phase focusing effect
Answer» A. prevent mode jumping

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116.	The primary purpose of the helix in a traveling-wave tube is to
A.	prevent the electron beam from spreading in the long tube
B.	reduce the axial velocity of the rf field
C.	ensure broadband operationreduce the noise figure
D.	none ofthe above.
Answer» B. reduce the axial velocity of the rf field

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117.	The TWT is sometimes preferred to the magnetron as a radar transmitter output tube because it is
A.	capable of a longer duty cycle
B.	a more efficient bandwidth
C.	more broadband
D.	less noisy
Answer» A. capable of a longer duty cycle

discuss

118.	A magnetron whose oscillating frequency is electronically adjustable over a wide range is called a
A.	coaxial magnetron
B.	dither-tuned magnetron
C.	frequency agile magnetron
D.	vtm
Answer» D. vtm

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119.	A disadvantage of microstrip compared with strip line is that micro strip
A.	does not readily lend itself to printed circuit techniques
B.	is more likely to radiate
C.	is bulkier
D.	is more expensive and complex to manufacture
Answer» A. does not readily lend itself to printed circuit techniques

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120.	For best low-level noise performance in the X-band, an amplifier should use
A.	a bipolar transistor
B.	a gunn diode
C.	a step-recovery diode
D.	an impatt diode
Answer» C. a step-recovery diode

discuss

121.	Considering a coaxial transmission line, maximum voltage on the line divided by the minimum voltage equals the
A.	characteristic impedance
B.	iswr
C.	vswr
D.	inductive reactance
Answer» C. vswr

discuss

122.	In a transmission line, if the SWR or maximum current to a minimum current ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is
A.	1:4
B.	4:1
C.	1:2
D.	2:1
Answer» D. 2:1

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123.	The load is properly matched with the transmission line if the standing wave ratio is equal to
A.	50
B.	10
C.	5
D.	1
Answer» D. 1

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124.	Which of the following is used to measure SWR?
A.	multimeter
B.	spectrum analyzer
C.	reflectometer
D.	oscilloscope
Answer» C. reflectometer

discuss

125.	Reflections on a transmission line can occur when
A.	impedance of the source and load are matched
B.	impedance of the source and the load are mismatched
C.	resonance conditions are obtained
D.	power transfer between source and load is maximum
Answer» B. impedance of the source and the load are mismatched

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126.	A measure of the mismatched between line and load impedance is called as
A.	reflection coefficient
B.	standing wave ratio
C.	loss
D.	standing waves
Answer» B. standing wave ratio

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127.	Power density is basically termed as power per unit are
A.	reflected
B.	radiated
C.	diffracted
D.	refracted
Answer» B. radiated

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128.	Parabolic and lens antennas are extensively used for
A.	short waves
B.	micro waves
C.	medium frequency waves
D.	all of the above
Answer» B. micro waves

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129.	The television receiver antennas are usually
A.	parabolic dish type
B.	helical antennas
C.	dipoles
D.	none of the above
Answer» C. dipoles

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130.	Lens antennas used for microwaves are usually made of
A.	paraboloid surfaces
B.	polystyrene
C.	dielectric media having large refractive index
D.	glass of low refractive index
Answer» B. polystyrene

discuss

131.	One of the following antenna types is best excited from a waveguide
A.	horn antenna
B.	helical antenna
C.	biconical antenna
D.	log periodic antenna
Answer» A. horn antenna

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132.	The parabolic and lens antennas are used extensively at
A.	sw
B.	mw
C.	microwaves
D.	al of the above
Answer» C. microwaves

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133.	Micro strip can be fabricated using:
A.	photolithographic process
B.	electrochemical process
C.	mechanical methods
D.	none of the above
Answer» A. photolithographic process

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134.	slotted antenna is used for
A.	uhf
B.	vhf
C.	none of the above
D.	both uhf and vhf
Answer» D. both uhf and vhf

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135.	The radar in which both transmission and reception is done using the same antenna are called:
A.	monostatic
B.	bistatic
C.	dipole radar
D.	monopole radar
Answer» A. monostatic

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136.	__________ system obtains information about a target by transmitting a signal and receiving the echo from the target.
A.	radar
B.	sonar
C.	radiometer
D.	none of the above
Answer» A. radar

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137.	The solid area through which all the power radiated by the antenna is:
A.	beam area
B.	effective area
C.	aperture area
D.	beam efficiency
Answer» A. beam area

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138.	Which one of the following device behaviour is governed by bulk effect?
A.	impatt diode
B.	gunn diode
C.	tunnel diode
D.	pin diode
Answer» B. gunn diode

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139.	In a MTI radar, the quartz delay line is used to
A.	match the phase of coho and output oscillator
B.	match the phase of coho and stalo
C.	match the signal with echo
D.	subtract a complete scan from previous scan
Answer» D. subtract a complete scan from previous scan

discuss

140.	Voltage reflection coefficient can be defined as:
A.	ratio of amplitude of reflected voltage wave to the transmitted voltage wave
B.	ratio of amplitude of reflected voltage to the incident voltage wave
C.	ratio of load impedance to the characteristic impedance of the transmission line
D.	none of the mentioned
Answer» B. ratio of amplitude of reflected voltage to the incident voltage wave

discuss

141.	Flow of power in transmission line takes place through:
A.	electric field and magnetic field
B.	voltage and current
C.	voltage
D.	electric field
Answer» A. electric field and magnetic field

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142.	If a transmission line of a characteristics impedance 50 Ω is terminated with a load impedance of 100 Ω, then the reflection co efficient is:
A.	0.3334
B.	0.6667
C.	1.6
D.	1.333
Answer» A. 0.3334

discuss

143.	If a transmission line of characteristic impedance 50 Ω is to be matched to a load of 100Ω, then the characteristic impedance of the ƛ/4 transmission line to be used is:
A.	75 Ω
B.	50 Ω
C.	100 Ω
D.	70.71 Ω
Answer» D. 70.71 Ω

discuss

144.	If there is no standing wave on a transmission line, then the value of SWR is:
A.	0
B.	1
C.	infinity
D.	insufficient data
Answer» B. 1

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145.	If a transmission line of characteristic impedance 50 Ω is terminated with a load impedance of 150 Ω , then VSWR is:
A.	0.75
B.	0.5
C.	2
D.	none of the mentioned
Answer» A. 0.75

discuss

146.	Smith chart is based on the polar plot of:
A.	reactance
B.	voltage
C.	current
D.	voltage reflection co-efficient
Answer» D. voltage reflection co-efficient

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147.	To get an admittance chart from an impedance chart:
A.	smith chart has to be rotated by 90⁰
B.	smith chart has to be rotated by 180⁰
C.	admittance chart cannot be obtained from the impedance chart anyway.
D.	none of the mentioned
Answer» B. smith chart has to be rotated by 180⁰

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148.	Propagation constant γ is given by:
A.	α+jβ
B.	α-jβ
C.	α/jβ
D.	α.jβ
Answer» A. α+jβ

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149.	The key difference between circuit theory and transmission line theory is:
A.	circuit elements
B.	voltage
C.	current
D.	electrical size
Answer» D. electrical size

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150.	Transmission line is a _________ parameter network.
A.	lumped
B.	distributed
C.	active
D.	none of the mentioned
Answer» B. distributed

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180+ Radiation and Microwave Techniques Solved MCQs

The phase velocity for the TE10 mode in an air filled rectangular waveguide is

The phase velocity of an electrometric wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is

. Consider an air filled rectangular waveguide with a cross – section of5 cm × 3 cm. For this waveguide, the cut off frequency (in MHz) of TE21mode is

The cut off frequency of waveguide depends upon

ency for the dominant mode is

ency of 30 GHz is (free space impedance 0 =377 Ω)

When an electromagnetic waves are propagated in a waveguide

Which of the following waveguides tuning components is not easily adjustable?

A directional coupler with three or more holes is sometimes used in preference to the two-hole couple

A ferrite is

A PIN diode is

A microwave tube amplifier uses an axial magnetic field and a radial electric field. This is the

Indicate the false statement. Transit time in microwave tubes will be reduced if

The multicavity klystron

The cavity magnetron uses strapping to

The primary purpose of the helix in a traveling-wave tube is to

The TWT is sometimes preferred to the magnetron as a radar transmitter output tube because it is

A magnetron whose oscillating frequency is electronically adjustable over a wide range is called a

A disadvantage of microstrip compared with strip line is that micro strip

For best low-level noise performance in the X-band, an amplifier should use

Considering a coaxial transmission line, maximum voltage on the line divided by the minimum voltage equals the

In a transmission line, if the SWR or maximum current to a minimum current ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is

The load is properly matched with the transmission line if the standing wave ratio is equal to

Which of the following is used to measure SWR?

Reflections on a transmission line can occur when

A measure of the mismatched between line and load impedance is called as

Power density is basically termed as power per unit are

Parabolic and lens antennas are extensively used for

The television receiver antennas are usually

Lens antennas used for microwaves are usually made of

One of the following antenna types is best excited from a waveguide

The parabolic and lens antennas are used extensively at

Micro strip can be fabricated using:

slotted antenna is used for

The radar in which both transmission and reception is done using the same antenna are called:

__________ system obtains information about a target by transmitting a signal and receiving the echo from the target.

The solid area through which all the power radiated by the antenna is:

Which one of the following device behaviour is governed by bulk effect?

In a MTI radar, the quartz delay line is used to

Voltage reflection coefficient can be defined as:

Flow of power in transmission line takes place through:

If a transmission line of a characteristics impedance 50 Ω is terminated with a load impedance of 100 Ω, then the reflection co efficient is:

If a transmission line of characteristic impedance 50 Ω is to be matched to a load of 100Ω, then the characteristic impedance of the ƛ/4 transmission line to be used is:

If there is no standing wave on a transmission line, then the value of SWR is:

If a transmission line of characteristic impedance 50 Ω is terminated with a load impedance of 150 Ω , then VSWR is:

Smith chart is based on the polar plot of:

To get an admittance chart from an impedance chart:

Propagation constant γ is given by:

The key difference between circuit theory and transmission line theory is:

Transmission line is a _________ parameter network.

The phase velocity of an electrometric wave propagating in a hollow metallic
rectangular waveguide in the TE10 mode is

. Consider an air filled rectangular waveguide with a cross – section of5 cm × 3 cm.
For this waveguide, the cut off frequency (in MHz) of TE21mode is

ency for
the dominant mode is

ency of 30
GHz is (free space impedance 0 =377 Ω)

A directional coupler with three or more holes is sometimes used in preference to
the two-hole couple

A microwave tube amplifier uses an axial magnetic field and a radial electric field.
This is the

The TWT is sometimes preferred to the magnetron as a radar transmitter output
tube because it is

A magnetron whose oscillating frequency is electronically adjustable over a wide
range is called a

Considering a coaxial transmission line, maximum voltage on the line divided by
the minimum voltage equals the

In a transmission line, if the SWR or maximum current to a minimum current
ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is

The load is properly matched with the transmission line if the standing wave ratio
is equal to

The radar in which both transmission and reception is done using the same
antenna are called:

__________ system obtains information about a target by transmitting a signal
and receiving the echo from the target.