# 180+ Radiation and Microwave Techniques Solved MCQs

22
39.6k
1.

## . Which of the following parameters is not a primary parameter?

A. resistance
B. attenuation constant
C. capacitance
D. conductance
Answer» B. attenuation constant
2.

A. 50
B. 20
C. 1000
D. 125
3.

## For a matched line, the input impedance will be equal to

B. characteristic impedance
C. output impedance
D. zero
Answer» B. characteristic impedance
4.

A. 20
B. 125
C. 200
D. 75
5.

## The average power in an electromagnetic wave is given by

A. propagation constant
B. pointing vector
C. phase constant
D. attenuation constant
Answer» B. pointing vector
6.

## The characteristic impedance of a transmission line is normally chosen to be

A. 50
B. 75
C. 50 or 75
D. 100
Answer» C. 50 or 75
7.

## Identify the material which is not present in a transmission line setup.

A. waveguides
B. cavity resonator
C. antenna
D. oscillator
8.

A. 2
B. 3
C. 1/2
D. 4
9.

## The range of the standing wave ratio is

A. 0 < s < 1
B. -1 < s < 1
C. 1 < s < ∞
D. 0 < s < ∞
Answer» C. 1 < s < ∞
10.

## The best stub selection for the transmission line will be

A. series open
B. series short
C. shunt open
D. shunt short
Answer» D. shunt short
11.

## The phenomenon employed in the waveguide operation is

A. reflection
B. refraction
C. total internal reflection
Answer» C. total internal reflection
12.

## The dominant mode in waveguide is the mode which has

A. highest frequency
B. highest wavelength
C. lowest phase constant
D. highest attenuation
Answer» B. highest wavelength
13.

## The modes are calculated from which parameter?

A. frequency
B. wavelength
C. phase constant
D. v number
Answer» D. v number
14.

## The circular waveguides use which function in the frequency calculation?

A. laplace function
B. schottky function
C. bessel function
D. transfer function
Answer» C. bessel function
15.

## The scattering parameters are used to indicate the

A. permittivity and permeability
B. electric and magnetic field intensities
C. reflection and transmission coefficients
D. frequency and wavelength
Answer» C. reflection and transmission coefficients
16.

A. 1
B. 0
C. -1
D.
17.

## The waveguides are materials with characteristics of

A. low bulk resistivity
B. high bulk resistivity
C. high conductivity
D. low conductivity
Answer» A. low bulk resistivity
18.

A. hz
B. khz
C. mhz
D. ghz
19.

## In rectangular waveguides, the dimensions a and b represent the

A. broad wall dimensions
B. broad wall and side wall dimension respectively
C. side wall and broad wall dimension respectively
D. side wall dimensions
Answer» B. broad wall and side wall dimension respectively
20.

A. 3 mhz
B. 3 ghz
C. 6 mhz
D. 6 ghz
Answer» D. 6 ghz
21.

## In transverse electric waves, which of the following is true?

A. e is parallel to h
B. e is parallel to wave direction
C. e is transverse to wave direction
D. h is transverse to wave direction
Answer» C. e is transverse to wave direction
22.

A. te01
B. te10
C. tm01
D. tm10
23.

## The propagation constant for a lossless transmission line will be

A. real
B. complex
C. real and equal to phase constant
D. complex and equal to phase constant
Answer» D. complex and equal to phase constant
24.

## Which of the following parameter is non zero for a lossless line?

A. attenuation
B. resistance
C. conductance
D. phase constant
Answer» D. phase constant
25.

## The phase and group velocities does not depend on which of the following?

A. frequency
B. wavelength
C. phase constant
D. attenuation constant
Answer» D. attenuation constant
26.

## amplifier.

A. linear beam
B. crossed field
C. parallel field
D. none of the mentioned
Answer» A. linear beam
27.

## reflector electrode after the cavity.

A. backward wave oscillator
B. reflex klystron
C. travelling wave tube
D. magnetrons
Answer» B. reflex klystron
28.

## A major disadvantage of klystron amplifier is:

A. low power gain
B. low bandwidth
C. high source power
D. design complexity
Answer» B. low bandwidth
29.

## The material out of which PIN diode is made is:

A. silicon
B. germanium
C. gaas
D. none of the mentioned
30.

## GaAs is used in the fabrication of GUNN diodes because:

A. gaas is cost effective
B. it less temperature sensitive
C. it has low conduction band electrons
D. less forbidden energy gap
Answer» D. less forbidden energy gap
31.

## GaAs is used in fabricating Gunn diode. Gunn diode is:

A. bulk device
B. sliced device
C. made of different type of semiconductor layers
D. none of the mentioned
Answer» A. bulk device
32.

## The mode of operation in which the Gunn diode is not stable is:

A. gunn oscillation mode
B. limited space charge accumulation mode
C. stable amplification mode
D. bias circuit oscillation mode
Answer» A. gunn oscillation mode
33.

## an IMPATT diode, it results in:

A. avalanche multiplication
B. break down of depletion region
C. high reverse saturation current
D. none of the mentioned
Answer» A. avalanche multiplication
34.

## maintain at safe limit.

A. average current
B. average voltage
C. average bias voltage
D. average resistance
Answer» A. average current
35.

## Expression for the characteristic impedance of a transmission line(λ/4) used for impedance matching is:

A. z1=√(zₒr)l
B. z1=√(zₒ/r)l
C. z1=√(zₒ+r)l
D. none of the mentioned
36.

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

A. 1
B. 0
C. infinity
D. insufficient data
37.

## When a λ/4 transmission line is used for impedance matching, then which of the following is valid?

A. standing waves are present on the λ/4 transmission line
B. no standing waves on the λ/4 transmission line
C. standing waves are not present both on the feed line and the matching λ/4 line
D. standing waves are present on both the feed line and the matching λ/4 line
Answer» A. standing waves are present on the λ/4 transmission line
38.

## The lowest mode of TE mode propagation in a circular waveguide is:

A. te10 mode
B. te00 mode
C. te01 mode
D. te11 mode
Answer» C. te01 mode
39.

A. g
B. c
C. l
D. r
40.

## Which of the following parameters does not exist in the transmission line equation?

A. r
B. zo
C. zl
D. propagation constant
41.

A. 50
B. 25
C. 75
D. 35.35
42.

A. 17
B. 3
C. 10/7
D. 0.7
43.

A. 1/4
B. 1/8
C. 1/2
D. 3/4
44.

## The major disadvantage of single stub tuning is:

A. it requires a variable length of line between the load and the stub
B. it involves 2 variable parameters
C. complex calculation
D. none of the mentioned
Answer» A. it requires a variable length of line between the load and the stub
45.

## In a double stub tuner circuit, the load is of _______ length from the first stub.

A. fixed length
B. arbitrary length
C. depends on the load impedance to be matched
D. depends on the characteristic impedance of the transmission line
Answer» B. arbitrary length
46.

## The major advantage of double stub tuning is:

A. it uses 2 tuning stubs in fixed positions
B. it involves 2 stubs
C. length of the stub is variable
D. none of the mentioned
Answer» A. it uses 2 tuning stubs in fixed positions
47.

## The modes of propagation supported by a rectangular wave guide is:

A. tm, tem, te modes
B. tm, te
C. tm, tem
D. te, tem
Answer» B. tm, te
48.

## Dominant mode is defined as:

A. mode with the lowest cut off frequency
B. mode with the highest cut off frequency
C. any tem mode is called a dominant mode
D. none of the mentioned
Answer» A. mode with the lowest cut off frequency
49.

## The product of the phase and the group velocities is given by the

A. speed of light
B. speed of light/2
C. 2 x speed of light
D. (speed of light)/4
Answer» D. (speed of light)/4
50.

## For TE1ₒ mode, if the waveguide is filled with air and the broader dimension of the waveguide is 2 cm, then the cutoff frequency is:

A. 5 mhz
B. 7.5 mhz
C. 7.5 ghz
D. 5 ghz
Answer» C. 7.5 ghz
51.

A. 100
B. 500
C. 50
D. 1000
52.

## The klystron tube used in a klystron amplifier is a _________ type beam amplifier.

A. linear beam
B. crossed field
C. parallel field
D. none of the mentioned
Answer» A. linear beam
53.

A. three
B. two
C. four
D. one
54.

## The resistance of the PIN diode with positive bias voltage:

A. increases
B. decreases
C. remains constant
D. insufficient data
55.

## Microstrip line can support a pure TEM wave.

A. true
B. false
C. microstrip supports only tm mode
D. microstrip supports only te mode
56.

## The effective dielectric constant ∈r for a microstrip line:

A. varies with frequency
B. independent of frequency
C. it is a constant for a certain material
D. depends on the material used to make microstrip
Answer» B. independent of frequency
57.

## The arcs of circles on smith chart represent

A. normalised resistance or conductance
B. different values of swr
C. normalised reactance or susceptance
D. none of the above
Answer» C. normalised reactance or susceptance
58.

## The characteristic impedance of a transmission line is

A. directly proportional to its length
B. inversely proportional to its length
C. independent of its length
D. none of the above
Answer» C. independent of its length
59.

## Standing wave ratio (SWR) equal to unity implies that

A. the transmission line is open circuited
B. the transmission line is short circuited
C. the transmission line\s characteristic impedance equals load impedance
D. none of the above
Answer» C. the transmission line\s characteristic impedance equals load impedance
60.

## ), The normalised load impedance is

A. (1 + j 2)
B. (2500 + j 5000)
C. (0.5 +j)
D. none of the above
Answer» A. (1 + j 2)
61.

A. 25.2
B. 22.8
C. 28.8
D. 20
62.

A. 25
B. 1.33
C. 7
D. 0.75
63.

## Input impedance of a shorted lossless line of length π/4 is

A. zero
B. infinity
C. zo
D. none of the above
64.

A. 0.67
B. 1.2
C. 1
D. 1.5
65.

A. 0
B. 3
C. 2
D. 4
66.

## pF/m and an inductance of 75 nH/m

A. 5 ohm
B. 50 ohm
C. 500 ohm
D. 5000 ohm
Answer» B. 50 ohm
67.

A. 2
B. 1
C. 0.5
D. 3.14
68.

A. te11
B. tm11
C. te10
D. tm10
69.

A. stub
B. iris
C. screw
D. plunger
70.

## What is the wavelength of a wave in a waveguide?

A. greater than in free space
B. depends only on the waveguide dimensions and the free-space wavelength
C. inversely proportional to the phase velocity
D. inversely proportional to the group velocity
Answer» A. greater than in free space
71.

## What is the cut-off frequency of a waveguide?

A. the highest frequency the waveguide operates
B. the lowest frequency the waveguide operates
C. the same as the operating frequency
D. the only frequency the waveguide operates
Answer» B. the lowest frequency the waveguide operates
72.

A. ridged
B. circular
C. rectangular
D. flexible
73.

## Out of following list, is not directional coupler

A. bathe hole
B. two hole
C. rate race
D. magic hole
Answer» D. magic hole
74.

A. a = b
B. a>b
C. a<b
D. ab=0
75.

## Materials generally preferred for wave guides are

A. brass and aluminium
B. cast iron and steel
C. non-metallic solids including plastics
D. all of the above
Answer» A. brass and aluminium
76.

## cm and b = 1.5 cm with μ = 1 and ε = 2.25 is

A. 377 ohm
B. 327 ohm
C. 227 ohm
D. 127 ohm
Answer» C. 227 ohm
77.

## 75GHz?

A. 9.2 cm
B. 3.2 cm
C. 0.6 m
D. 12 cm
Answer» A. 9.2 cm
78.

A. 4.5 ghz
B. 5 ghz
C. 5.5 ghz
D. 6 ghz
Answer» D. 6 ghz
79.

A. 1 cm
B. 2 cm
C. 3 cm
D. 4 cm
Answer» B. 2 cm
80.

## A major disadvantage of klystron amplifier is

A. low power gain
B. low bandwidth
C. high source power
D. design complexity
Answer» B. low bandwidth
81.

A. three
B. two
C. four
D. one
82.

## The resistance of the PIN diode with positive bias voltage

A. increases
B. decreases
C. remains constant
D. insufficient data
83.

## GaAs is used in the fabrication of GUNN diodes because

A. gaas is cost effective
B. it less temperature sensitive
C. it has low conduction band electrons
D. less forbidden energy gap
Answer» D. less forbidden energy gap
84.

A. two
B. three
C. four
D. five
85.

## The number of semiconductor layers in IMPATT diode is:

A. two
B. three
C. four
D. none of the mentioned
86.

## The cavity resonator

A. is equivalent to an lc resonant circuit
B. in a reflect klystron has its output taken from the reflector plate
C. produces a frequency which is independent of the cavity size.
D. has a low q factor for narrow operation.
Answer» A. is equivalent to an lc resonant circuit
87.

## A traveling-wave tube (TWT) amplifies by virtue of

A. the absorption of energy by the signal from an electron stream
B. the effect of an external magnetic field
C. the energy contained the cavity resonators
D. the energy liberated form the collector
Answer» A. the absorption of energy by the signal from an electron stream
88.

## Which of the following is used as a high power microwave oscillator?

A. thyratron
B. magnetron
C. klystron
D. reflex-klystron
89.

## The characterstic impedance of a transmission line depends upon

A. shape of the conductor
B. surface treatment of the conductor
C. conductivity of the material
D. geometrical configuration of conductors
Answer» D. geometrical configuration of conductors
90.

## In order to reduce skin effect at ultra high frequencies,

A. conductors are painted
B. conductors are anodized
C. copper rodes with silver plating are used
D. copper lubes with silver plating are used
Answer» D. copper lubes with silver plating are used
91.

## Which of the following are constants of transmission lines

A. resistance
B. inductance
C. capacitance
D. all of the above
Answer» D. all of the above
92.

## Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in

A. a short circuit
B. an open circuit
C. a complex impedance
D. pure reactance
Answer» C. a complex impedance
93.

## Major advantage of a quarter wave transformer is

A. proper matching
B. high gain
C. broader band width
D. none of the above
94.

## The reactances associated with the transmission line due to discontinuities:

A. can be ignored
B. have to be matched
C. discontinuities do no exist
D. none of the above
Answer» C. discontinuities do no exist
95.

## The wave impedance of air for a wave propagating in it is

A. 377 Ω
B. 345 Ω
C. insufficient data
D. none of the above
Answer» A. 377 Ω
96.

A. 10
B. 2
C. 1
D. infinity
97.

## A rectangular air – filled waveguide has a cross section of 4  × 10 The minimum frequency which can propagation in the waveguide is

A. 1.5 ghz
B. 2.5 ghz
C. 2.0 ghz
D. 3.0 ghz
Answer» A. 1.5 ghz
98.

A. te110
B. tm110
C. te011
D. mt111
99.

## The phase velocity of waves propagation in hollow metal waveguide is

A. greater than velocity of light in free space
B. less than velocity of light in free space
C. equal to velocity of light in free space
D. equal to group velocity
Answer» C. equal to velocity of light in free space
100.

## The dominant mode in a rectangular waveguide is TE10 because this mode has

A. no attenuation
B. no cut off
C. no magnetic field component
D. the highest cut off wavelength
Answer» D. the highest cut off wavelength