ANTENNAS, WAVE PROPAGATION AND TRANSMISSION LINES Interview Questions and Answers, Objective type Questions and Answers


1. The ratio of the radii required to give a 60 ohm coaxial line filled with PTFE of ?r = 2, ┬Ár =  1 is
2. An undergrounded antenna near the ground
3. To couple a coaxial line to a parallel wire line, it is best to use :
4. Electrical length of an antenna is
5. Skip distance is the :
6. The attenuation in wave guides near the cut off frequency is
7. Which of the following statements is not true for rhombic antenna ?
8. If length of the antenna is increased, the directive gain
9. The WF band is ________.
10. Long wave transmission corresponds to frequency range of ______.
11.     In a broadside array, the maximum radiation occurs:
12.     Electromagnetic cavity.resonators are energy storage devices and arc used in :
13.     A half wave dipolc has maximum response in
14.     An antenna is cut for a resonant frequency of 10 MHz then the antenna can handle a BW of 2 MHz. quality factor is
15.     A haif-wavc dipole antenna is required to radiate 250 MHz. signal. If the velocity factor of the antenna elements is 0.85, its length should be
18.     VLF waves are used for communication system because
16.     A lossless line of 50 ohms is terminated in a load of 100 ohms resistive. The VSWR is
17.     A higher value of Standing Wave Ratio indicates
18.     A (75 -j 40)O load is connected to a coaxial line of Zo =. 75O at 6 MHz. The besi method of matching consists in connecting .
19.     An antenna is to be used to receive a lone-of-sight wave transmitted from an antenna located at a distance of 50 miles from this installation which is 800 ft in height. The minimum necessary height of the receiving antenna is
20.     A low loss transmission line has
21.     Frequencies in the UHF range propagate by means of
22.     Radiation intensity does not depend upon
23.     For T.V the antenna that is widely used is
23.     The condition for distortionless line is given by  
24.   The VSWR of a transmission line is
25.   Which type of fading causes serious distortion of modulated signal:
26.   Which of the following antennas is the standard reference antenna for the directiveness ?
27.   As electromagnetic waves travel in free space then only one of the following can happen
28.  The following is a wideband antenna :
29.  Antenna commonly used for microwave links are
30.  Directive gain of elementary doublet relative to isotropic radiator is
31. Which of the following is a non-resonant antenna ?
32. The intended frequency of operation of a dipole antenna cut to a length of 3.5 m is
33. Which of the following is high frequency transmission line ?
34. Zoning is used with a dielectric antenna in order to
35. Which of the following is a vector quantity ?
36. Top loading is used with an antenna in order to increase its
37.   Which of the following does not exist in waveguides
38.   Cassegrain feed is used with a parabolic reflector to
39.   Which is the least important layer in regard to high frequency propagation ?
40.   Radiation pattern of one wavelength long antenna and centre fed has no. of lobes equal to
41.   For critical frequency of 10 MHz, the maximum usable frequency for angle of incidence of 60° will be
42.   The effective height of a vertical radiator can be increased by
43. A half wave dipole at a frequency of 100 MHz has a length of
44. For TV reception, antenna commonly used is:
45. Antenna radiaiton efficiency can be increased by
46. For a plane good conductor, skin depth varies:
47. Which of the following antennas can be used in direction finding ?
48. In an end fire array, the maximum radiation occurs :
49. In radar system if the antenna diameter is increased by a factor of 4, the minimum range will increased by a factor of
50. Which of the following statements is not true for F2 layer ?
51. The total field produced by an antenna array system at a great distance from it is
52. Which of the following characteristics is shown by microwave antenna ?
53. Compared with equivalent transmission lines, 36 Hz waveguides (indicate false statement)
54. According to maximum power transfer theorem, if the load is inductive, the source should be
55. For a frequency of 300 MHz, the wavelength will be
56. UHF band is given by
57. For transmission iine-load matching over a range of frequencies, it is best to use a:
58. The gain of a half wave dipole is
59. In case of antenna the lower value of Q indicates
60. Television receiver antenna is usually
61. A folded dipole antenna is conveniently connected to
62. "Counterpoise conductor ground system" is used in case of
63. The characteristic impedance of a quarter wave transformer connected in between a load of 100 ohms and a transmission line of characteristic impedance of 225 ohms is
64. If the receiving antenna is 16 m above the ground, then the total radio horizon will be
65. The maximum effective aperture of a microwave antenna which has a directivity of 900, will be
66. Which of the following has longest wavelength?
67. Radiation resistance in a given direction is the:
68. A TV transmitting aerial is fixsd on top of a 150 m tower located on a mountain 1200 m high. The range of the transmitter is
69. In a home TV receiver, the lead in form the antenna is
70. Yagi antenna contains
71. Short circuited stubs are preferred to open circuited stubs because open circuit stubs :
72. Radar antennas are usually
73. A- conductor A is enclosed in a second conductor B. If there is a third conductor C external to B, then conductor A would be
74. The thermal noise is due to random
75. A typical Radar antenna has beam width of about:
76. The height of the transmitting antenna is 225 m above ground level. Its radio horizon will be
77. The essential condition for antenna array to be linear is that
78. Which of the following antenna gives circular polarization ?
79. The term critical frequency denotes
80. High frequency waves are
81. The frequency of normal sound wave determines
82.  An antenna is ______.
83. VHF wave propagatets with the help of
84. A transmission line of length ?/4 < I < ?/2, is open circuited at the far end. The input impedance is:
85. The gain of an isotropic antenna is
86. WR 284 has inside dimensions of 7 x 3.5 cm operating in TEio mode and filled with dielectric er = 9. The cut off frequency is
87. If reflection coefficient is 1/5 then corresponding VSWR is given by
88. Antenna reciprocity is put to use in
89. The critical frequency for a layer is
90. The duration of sunspot cycle is
91. The waveform of sound wave determines
92. Which statement regarding the Yagi-Uda antenna is wrong ?
93. In series excitation of a tower antenna
94. For a plane good conductor, skin depth yaries
95. The statement that the line integral of magnetic field about any closed path is exactly equal to the direct current enclosed by that path, is known as
96. In a horizontal polarized wave
97. The maximum gain of an antenna using an evenly illuminated 6 ft. paraboloid reflector used at 6 MHz will be
98. Microwave signals transmitted towards the sky are
99. The frequency of microwaves is
100. The Poynling vector represents,
101. A Rhombic antenna is a
102. The gain of a currect element is
103. Compared to equivalent transmission lines at low frequencies, the waveguides :
104. Radiation resistance, in ohms, of a half wave folded dipole is
105. The sound intensity level due to radio playmg loudly is of the order
106. Which of the followings statement is not true for beam-width of an antenna?
        Beam-width is the angle within which
107. Which of the following constitute the loss resistance of an antenna ?
108. The function of Cassegrain feed used with parabolic reflector is
109. A range of microwave frequencies more easily passed by the atmosphere than are the others is known as a
110. Which of the following will have least wave-length
111. An underground antenna near the ground
112. The ratio of the radius to separation required to give a 300 ohm 2 wire transmission Sine in open space is
113. In case of surface wave, the field strength at a point is directly proportional to
114. Which of the following is abnormal variation in ionosphere ?
115. Which statement regarding endfire array is wrong ?

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