Quiznetik

Radiation and Microwave Techniques | Set 1

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

Correct : B. attenuation constant

2. ohm is

Correct : D. 125

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

Correct : B. characteristic impedance

4. wave ratio of 2.5 is

Correct : B. 125

5. The average power in an electromagnetic wave is given by

Correct : B. pointing vector

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

Correct : C. 50 or 75

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

Correct : D. oscillator

8. respectively. The standing wave ratio is

Correct : B. 3

9. The range of the standing wave ratio is

Correct : C. 1 < s < ∞

10. The best stub selection for the transmission line will be

Correct : D. shunt short

11. The phenomenon employed in the waveguide operation is

Correct : C. total internal reflection

12. The dominant mode in waveguide is the mode which has

Correct : B. highest wavelength

13. The modes are calculated from which parameter?

Correct : D. v number

14. The circular waveguides use which function in the frequency calculation?

Correct : C. bessel function

15. The scattering parameters are used to indicate the

Correct : C. reflection and transmission coefficients

16. For the matched line, the parameters S12 and S21 are

Correct : B. 0

17. The waveguides are materials with characteristics of

Correct : A. low bulk resistivity

18. range of

Correct : D. ghz

19. In rectangular waveguides, the dimensions a and b represent the

Correct : B. broad wall and side wall dimension respectively

20. The cut off frequency for a waveguide to operate is

Correct : D. 6 ghz

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

Correct : C. e is transverse to wave direction

22. The dominant mode in rectangular waveguide is

Correct : B. te10

23. The propagation constant for a lossless transmission line will be

Correct : D. complex and equal to phase constant

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

Correct : D. phase constant

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

Correct : D. attenuation constant

26. amplifier.

Correct : A. linear beam

27. reflector electrode after the cavity.

Correct : B. reflex klystron

28. A major disadvantage of klystron amplifier is:

Correct : B. low bandwidth

29. The material out of which PIN diode is made is:

Correct : A. silicon

30. GaAs is used in the fabrication of GUNN diodes because:

Correct : D. less forbidden energy gap

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

Correct : A. bulk device

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

Correct : A. gunn oscillation mode

33. an IMPATT diode, it results in:

Correct : A. avalanche multiplication

34. maintain at safe limit.

Correct : A. average current

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

Correct : A. z1=√(zₒr)l

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

Correct : A. 1

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

Correct : A. standing waves are present on the λ/4 transmission line

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

Correct : C. te01 mode

39. Which primary parameter is uniformly distributed along the length of the conductor?

Correct : D. r

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

Correct : A. r

41. Find the characteristic impedance of a quarter wave with input and load impedances given by 50 and 25 respectively.

Correct : D. 35.35

42. Calculate the transmission coefficient, when the incident and transmitted amplitudes are 10 and 7 respectively.

Correct : D. 0.7

43. The reflection coefficient of a transmission line having characteristic and load impedances as 50 and 30 ohm respectively is

Correct : A. 1/4

44. The major disadvantage of single stub tuning is:

Correct : 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.

Correct : B. arbitrary length

46. The major advantage of double stub tuning is:

Correct : A. it uses 2 tuning stubs in fixed positions

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

Correct : B. tm, te

48. Dominant mode is defined as:

Correct : A. mode with the lowest cut off frequency

49. The product of the phase and the group velocities is given by the

Correct : 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:

Correct : C. 7.5 ghz

51. For dominant mode propagation in TE mode, if the rectangular waveguide has a broader dimension of 31.14 mm , then the cutoff wave number:

Correct : A. 100

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

Correct : A. linear beam

53. A PIN diode consists of ______number of semiconductor layers.

Correct : A. three

54. The resistance of the PIN diode with positive bias voltage:

Correct : B. decreases

55. Microstrip line can support a pure TEM wave.

Correct : B. false

56. The effective dielectric constant ∈r for a microstrip line:

Correct : B. independent of frequency

57. The arcs of circles on smith chart represent

Correct : C. normalised reactance or susceptance

58. The characteristic impedance of a transmission line is

Correct : C. independent of its length

59. Standing wave ratio (SWR) equal to unity implies that

Correct : C. the transmission line\s characteristic impedance equals load impedance

60. ), The normalised load impedance is

Correct : A. (1 + j 2)

61. V and a conduction current of 1.2A is

Correct : D. 20

62. and 9 respectively is

Correct : B. 1.33

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

Correct : C. zo

64. V. The SWR is

Correct : D. 1.5

65. The reflection coefficient on a transmission line is 1/3, what is the SWR

Correct : C. 2

66. pF/m and an inductance of 75 nH/m

Correct : B. 50 ohm

67. The wavelength of a line with a phase constant of 3.14 units is

Correct : A. 2

68. The dominant mode for rectangular waveguide is

Correct : C. te10

69. Following waveguide component not easily adjustable for tuning

Correct : B. iris

70. What is the wavelength of a wave in a waveguide?

Correct : A. greater than in free space

71. What is the cut-off frequency of a waveguide?

Correct : B. the lowest frequency the waveguide operates

72. For reduction in cross sectional dimension, waveguide to use is

Correct : A. ridged

73. Out of following list, is not directional coupler

Correct : D. magic hole

74. The condition which will satisfy the dimensions of the waveguide is

Correct : B. a>b

75. Materials generally preferred for wave guides are

Correct : A. brass and aluminium

76. cm and b = 1.5 cm with μ = 1 and ε = 2.25 is

Correct : C. 227 ohm

77. 75GHz?

Correct : A. 9.2 cm

78. 5 cm and 1 cm respectively is

Correct : D. 6 ghz

79. 5 GHz is

Correct : B. 2 cm

80. A major disadvantage of klystron amplifier is

Correct : B. low bandwidth

81. A PIN diode consists of........number of semiconductor layers.

Correct : A. three

82. The resistance of the PIN diode with positive bias voltage

Correct : B. decreases

83. GaAs is used in the fabrication of GUNN diodes because

Correct : D. less forbidden energy gap

84. The number of modes of operation for n type GaAs Gunn diode is

Correct : C. four

85. The number of semiconductor layers in IMPATT diode is:

Correct : C. four

86. The cavity resonator

Correct : A. is equivalent to an lc resonant circuit

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

Correct : 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?

Correct : B. magnetron

89. The characterstic impedance of a transmission line depends upon

Correct : D. geometrical configuration of conductors

90. In order to reduce skin effect at ultra high frequencies,

Correct : D. copper lubes with silver plating are used

91. Which of the following are constants of transmission lines

Correct : D. all of the above

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

Correct : C. a complex impedance

93. Major advantage of a quarter wave transformer is

Correct : C. broader band width

94. The reactances associated with the transmission line due to discontinuities:

Correct : C. discontinuities do no exist

95. The wave impedance of air for a wave propagating in it is

Correct : A. 377 Ω

96. A loss less line of characteristic impedance Z0 is terminated in pure reactance of - jZ0 value. VSWR is

Correct : 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

Correct : A. 1.5 ghz

98. Indicate which one of the following modes do not exist in a rectangularresonant cavity

Correct : A. te110

99. The phase velocity of waves propagation in hollow metal waveguide is

Correct : C. equal to velocity of light in free space

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

Correct : D. the highest cut off wavelength