Online Questions and Answers Topic Outline
- MCQs in Basic considerations
- MCQs in Wire Radiators in Space
- MCQs in Isotropic Radiator
- MCQs in Current and Voltage Distributions
- MCQs in Resonant and Non-resonant Antennas
- MCQs in Antenna Terms and Definition
- MCQs in Antenna Gain and Resistance
- MCQs in Bandwidth, Beamwidth and Polarization
- MCQs in Grounded and Ungrounded Antennas
- MCQs in Grounding Systems and Matching Systems
- MCQs in Antenna Types
- MCQs in Directional and Non-directional Antennas
- MCQs in Microwave Antennas
- MCQs in Wideband and Special Purpose Antennas
MCQs in Antennas Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part II of the Series
51. The current maximum in a Marconi antenna is found at
- A. the base of the antenna
- B. the center of the antenna
- C. some point between the base and the center of the antenna
- D. the top of the antenna
52. If an antenna is too short for the wavelength being used, the effective length can be increased by adding:
- A. capacitance in series
- B. inductance in series
- C. resistance in parallel
- D. resistance in series
53. Which of the following antennas is used for testing and adjusting a transmitter for proper modulation, amplifier operation and frequency accuracy?
- A. Elementary
- B. Real
- C. Isotropic
- D. Dummy
54. The power fed to a two-bay turnstile antenna is 100 watts. If the antenna has a 2 dB power gain, what is the effective radiated power?
- A. 317 watts
- B. 158 watts
- C. 200 watts
- D. 400 watts
55. What is the gain, in dB of a helical antenna with diameter of λ/3, 10 turns at pitch of λ/4, used at 100 MHz?
- A. 16
- B. 41.1
- C. 31.4
- D. 1.25
56. How is it possible to lower the resonant frequency of Hertz dipole antenna?
- A. By reducing the frequency at the transmitter
- B. By connecting a capacitor in series with the antenna
- C. By the connecting a resistor in series with the antenna
- D. By connecting an inductor in series with the antenna
57. Which of the following antennas receive signals in the horizontal plane equality well from all directions?
- A. Horizontal Hertz antenna
- B. Vertical loop antenna
- C. Vertical Yagi antenna
- D. A vertical antenna which is a quarter-wavelength long
58. If the length of a Hertz dipole is decreased
- A. its resonant frequency will be lowered its distributed inductance will be increased
- B. its distributed inductance will be decreased
- C. its resonant frequency will be increased
- D. its distributed capacitance between the antenna and ground will be increased.
59. A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, what is the antenna current at the feed-point?
- A. 4.0 A
- B. 2.2 A
- C. 1.25 A
- D. 2.0 A
60. A one-quarter wavelength shunt-fed vertical Marconi antenna
- A. has maximum radiation in a vertical direction
- B. must have a horizontal receiving antenna for the best reception
- C. must use a receiving antenna for the best reception
- D. must have a vertical receiving antenna for the best reception
61. A shunt-fed quarter-wavelength Marconi antenna
- A. has maximum RF impedance to ground at its feedpoint
- B. has a current null at its feedpoint
- C. has a zero DC resistance to ground
- D. has zero RF resistance to ground
62. The parasitic element of an antenna system will
- A. decrease its directivity
- B. increase its directivity
- C. give the antenna unidirectional properties
- D. both B and C
63. If the length of an antenna is changed from 2.5 meters to 2.8 meters, its resonant frequency will
- A. increase
- B. depend on the velocity factor so the resonant frequency can either be increased or decreased
- C. will be unchanged
- D. decrease
64. What is the effect of adding a capacitor in series with an antenna?
- A. The antenna’s resonant frequency will increase
- B. The antenna’s resonant frequency will decrease
- C. The antenna will be physically 5% longer than its electrical length
- D. A capacitor is never added in series with an antenna
65. How does the electric field strength of a standard broadcast station vary with the distance from the antenna?
- A. The field strength of a standard broadcast station vary with the distance from the antenna
- B. The field strength is directly proportional to the distance from the antenna
- C. The field strength remains constant regardless of the distance from the antenna
- D. The field strength varies inversely as the distance from the antenna
66. Stacking elements in a transmitting antenna system
- A. increases the field strength at the receiving antenna
- B. increases the directivity of the transmitter antenna
- C. decrease the size of the lobe in the radiation pattern
- D. both A and B
67. A vertical loop antenna has a
- A. unidirectional radiation pattern in the horizontal plane
- B. unidirectional radiation pattern in the vertical plane
- C. omnidirectional radiation pattern in the horizontal plane
- D. a bidirectional radiation pattern in the horizontal plane
68. In order to get maximum radiation to all surrounding points in the horizontal plane, the antenna used is a
- A. vertical loop
- B. vertical quarter-wavelength rod
- C. array which includes parasitic elements
- D. a horizontal Hertz dipole
69. What is the electrical wavelength of a 500 MHz signal?
- A. 60 centimeters
- B. 6 meters
- C. 0.06 meter
- D. 60 meters
70. If the antenna current is doubled, the field strength at a particular position is
- A. doubled
- B. halved
- C. multiplied by a factor of four
- D. divided by a factor of four
71. The rhombic antenna is primarily used for
- A. ground wave propagation
- B. space wave propagation
- C. ionosphere scatter propagation
- D. sky wave propagation
72. What antenna radiates equally in all directions?
- A. Vertical antenna
- B. isotropic antenna
- C. Horizontal antenna
- D. Dipole antenna
73. Actual height of antenna should be at least
- A. one wavelength
- B. half wavelength
- C. quarter wavelength
- D. three-fourth wavelength
74. Which antenna is not properly terminated?
- A. Resonant
- B. Non-resonant
- C. Isotropic
- D. Whip
75. ______ is an antenna array which is highly directional at right angles to the plane of the array?
- A. Broadside array
- B. End-fire array
- C. Turnstile array
- D. Log-periodic array
76. The directivity pattern of an isotropic radiator is
- A. a figure-8
- B. a sphere
- C. a unidirectional cardioid
- D. a parabola
77. An isotropic radiator is
- A. in the northern hemisphere
- B. an antenna high enough in the air
- C. an antenna whose directive pattern is substantially incredible
- D. a hypothetical, omnidirectional antenna
78. The purpose of stacking elements on an antenna.
- A. Sharper directional pattern
- B. increased gain
- C. Improved bandpass
- D. All of these
79. The advantage of using top loading in a shortened HF vertical antenna is
- A. lower quality factor
- B. greater structural strength
- C. higher losses
- D. improved radiation efficiency
80. Where are the voltage nodes in a half-wave antenna?
- A. At the ends
- B. Three-quarters of the way from the feed point toward the end
- C. One-half of the way from the feed point toward the end
- D. At the feed point
81. A theoretical reference antenna that provides a comparison for antenna measurements.
- A. Marconi antenna
- B. Isotropic radiator
- C. Yagi-Uda array
- D. Whip antenna
82. A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is hanged between two towers. What is the frequency of its third harmonic?
- A. 727 kHz
- B. 6546 kHz
- C. 436 kHz
- D. 6.546 kHz
83. In horizontal-dipole antenna, the polarization is
- A. in the vertical direction
- B. in the horizontal direction
- C. circular
- D. measured at the center of the antenna
84. Increasing the electrical length of an antenna means
- A. add an inductor in parallel
- B. add a capacitor in series
- C. add an inductor series
- D. add a resistor is series
85. Stacking antennas at various angles results in
- A. a more omnidirectional reception
- B. a more unidirectional reception
- C. a more omnidirectional reception
- D. an overall reception signal increase
86. What is driven element?
- A. Always the rearmost element
- B. Always the forward most element
- C. The element fed by the transmission line
- D. The element connected to the rotator
87. What is antenna bandwidth?
- A. Antenna length divided by the number of elements
- B. The angle between the half-power radiation points
- C. The angle formed between two imaginary lines drawn through
- D. The frequency range over which an antenna can be expected to operate satisfactorily
88. To lengthen an antenna electrically, add a
- A. resistor
- B. battery
- C. condult
- D. coil
89. What is the gain of an antenna over a half-wavelength dipole when it has 6 dB gain over an isotropic radiator?
- A. 6.0 dB
- B. 8.1 dB
- C. 3.9 dB
- D. 10.0 dB
90. What is the usual electrical length of a driven element in an HF beam antenna?
- A. ¼ wavelength
- B. ¾ wavelength
- C. ½ wavelength
- D. 1 wavelength
91. What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?
- A. It is increased
- B. It is decreased
- C. No change occurs
- D. It becomes flat
92. To electrically decrease the length of an antenna.
- A. add an inductor in series
- B. add an inductor in parallel
- C. add a resistor in series
- D. add a capacitor in series
93. Strong interference from one particular station can be eliminated by the use of
- A. noise limiters
- B. squelch circuits
- C. negative feedback
- D. wave traps in the antenna circuitry
94. It is useful to refer to an isotropic radiator.
- A. when comparing the gains of directional antennas
- B. when testing a transmission line for standing wave ratio
- C. when (in the northern hemisphere) directing the transmission
- D. when using a dummy load to tune a transmitter
95. A disadvantage of using a trap antenna.
- A. It will radiate harmonics
- B. It can only be used for single-bad operation
- C. It is too sharply directional at lower frequencies
- D. It must be neutralized
96. The input terminal impedance at the center of a folded dipole antenna is
- A. 72 Ω
- B. 300 Ω
- C. 50 Ω
- D. 73 Ω
97. When a capacitor is connected in series with a Marconi antenna?
- A. Antenna open circuit stops transmission
- B. An inductor of equal value must be added
- C. No change occurs to antenna
- D. Antenna resonant frequency increases
98. Where are the current nodes in a half-wave antenna?
- A. At the ends
- B. At the center
- C. Three-quarters of the way from the feed point toward the end
- D. One-half of the way from the feed point toward the end
99. For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance?
- A. As low as possible on the vertical radiator
- B. Near the center of the vertical radiator
- C. As close to the transmitter as possible
- D. At a voltage node
100. The effect of adding parasitic elements of a Hertz dipole is to
- A. make the antenna more omnidirectional
- B. reduce its resonant frequency
- C. increase the antenna’s power gain
- D. All of these
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