1. The major drawback of frequency multipliers is that they have:
Correct : C. complex design
2. Oscillators operating at millimeter wavelength are difficult to realize and are also less efficient.
Correct : A. true
3. A major disadvantage of frequency multipliers is that they multiply the noise factor along with frequency.
Correct : A. true
4. If a frequency multiplier has a multiplication factor of 10, then the increase in noise level due to frequency multiplication is:
Correct : B. 20 db
5. In a diode frequency multiplier, an input signal of frequency fo applied to the diode is terminated with at all frequencies other than required harmonic.
Correct : B. reactive impedance
6. Resistive multipliers are more efficient as compared to reactive multipliers.
Correct : B. false
7. Reactive multipliers have a disadvantage that they cannot be used at very high frequencies and they become less efficient.
Correct : A. true
8. For a resistive frequency multiplier of multiplication factor 2, the maximum theoretical conversion efficiency is:
Correct : B. 25 %
9. is a device that converts electrons to photons or vice-versa.
Correct : A. antenna
10. The basic equation of radiation that is applied to any antenna irrespective of the type of the antenna is:
Correct : A. il= qv
11. The number of patterns radiation pattern required to specify the characteristic are :
Correct : A. three
12. The beam width of the antenna pattern measured at half power points is called:
Correct : A. half power beam width
13. An antenna has a field pattern E (θ) =cos θ. cos 2θ. The first null beam width of the antenna is:
Correct : B. 900
14. The solid area through which all the power radiated by the antenna is:
Correct : A. beam area
15. A is a device that converts a guided electromagnetic wave on a transmission line into a plane wave propagating in free space.
Correct : A. transmitting antenna
16. Dipole antennas are an example for:
Correct : A. wire antennas
17. antennas consist of a regular arrangement of antenna elements with a feed network
Correct : B. array antennas
18. A parabolic reflector used for reception with the direct broadcast system is 18 inches in diameter and operates at 12.4 GHz. The far-field distance for this antenna is:
Correct : D. 17.3 m
19. of an antenna is a plot of the magnitude of the far field strength versus position around the antenna.
Correct : A. radiation pattern
20. Antennas having a constant pattern in the azimuthal plane are called
Correct : B. omni directional antenna
21. Beamwidth and directivity are both measures of the focusing ability of an antenna.
Correct : A. true
22. If the beam width of an antenna in two orthogonal planes are 300 and 600. Then the directivity of the antenna is:
Correct : B. 18
23. If the power input to an antenna is 100 mW and if the radiated power is measured to be 90 mW, then the efficiency of the antenna is:
Correct : C. 90 %
24. If an antenna has a directivity of 16 and radiation efficiency of 0.9, then the gain of the antenna is:
Correct : A. 16.2
25. Gain of an antenna is always greater than the directivity of the antenna.
Correct : B. false
26. A rectangular horn antenna has an aperture area of 3λ × 2λ. Then the maximum directivity that can be achieved by this rectangular horn antenna is:
Correct : C. 19 db
27. A rectangular horn antenna has an aperture area of 3λ × 2λ. If the aperture efficiency of an antenna is 90%, then the directivity of the antenna is:
Correct : B. 17.1 db
28. A resistor is operated at a temperature of 300 K, with a system bandwidth of 1 MHz then the noise power produced by the resistor is:
Correct : B. 4.14×10-15 watts
29. With an increase in operating frequency, the background noise temperature:
Correct : A. increases
30. The noise temperature of an antenna is given by the expression:
Correct : A. radtb + (1-rad) tp
31. Low is the G/T ratio of an antenna, higher is its efficiency.
Correct : B. false
32. has a constant power spectral density.
Correct : A. white noise
33. Slotted line is a transmission line configuration that allows the sampling of:
Correct : A. electric field amplitude of a standing wave on a terminated line
34. If the standing wave ratio for a transmission line is 1.4, then the reflection coefficient for the line is:
Correct : A. 0.16667
35. If the reflection coefficient of a transmission line is 0.4, then the standing wave ratio is:
Correct : B. 2.3333
36. In the expression for phase of the reflection coefficient, Lmin stands for :
Correct : A. distance between load and first voltage minimum
37. If the normalized load impedance of a transmission line is 2, then the reflection co- efficient is:
Correct : A. 0.33334
38. Link budget consists of calculation of
Correct : C. useful signal & interfering noise power
39. Which is the primary cost for degradation of error performance?
Correct : C. signal distortion & loss in signal to noise ratio
40. Which factor adds phase noise to the signal?
Correct : C. jitter & phase fluctuations
41. Antennas are used
Correct : C. as transducer & to focus
42. Mechanism contributing to a reduction in efficiency is called as
Correct : D. all of the mentioned
43. Space loss occurs due to a decrease in
Correct : A. electric field strength
44. Antenna’s efficiency is given by the ratio of
Correct : A. effective aperture to physical aperture
45. Effective radiated power of an isotropic radiator can be given as a product of
Correct : C. transmitted power and transmitting gain
46. A dipole antenna is also called as?
Correct : D. hertz antenna
47. The impedance at the center of the antenna is known as?
Correct : B. radiation resistance
48. What happens when the radiation resistance of the antenna matches the characteristic impedance of the transmission line?
Correct : D. swr is minimum
49. The type of dipole antenna that has a higher band width is called as?
Correct : A. conical antenna
50. The radiation pattern of a half-wave dipole has the shape of a
Correct : A. doughnut
51. What is the beam width for a half wave dipole antenna?
Correct : A. 90°
52. What does the beam width of an antenna tell us?
Correct : C. directivity
53. What is the power radiated by the antenna with gain called as?
Correct : C. effective radiated power
54. What is the radiation pattern of an isotropic radiator?
Correct : B. sphere
55. What is the impedance of the folded dipole antenna?
Correct : C. 300Ω
56. Which of the following antennas produce a vertical radiation pattern?
Correct : C. marconi antenna
57. The members of the antenna family which are made of wires of certain value in terms of operating wavelength are called:
Correct : C. dipole antenna
58. The antenna in which location of the feed determines the direction of the lobe are:
Correct : A. wire antenna
59. Based on the size of the loops, loop antennas are classified as small and large loops. This is the only classification of loop antenna.
Correct : B. false
60. Antenna that does not belong to the horn antenna family among the following are:
Correct : D. none of the mentioned
61. Reflector antennas are widely used to modify radiation patterns of radiating elements.
Correct : A. true
62. The pattern of the reflector in a reflector antenna is called:
Correct : B. secondary pattern
63. antennas have gain less than reflector antennas but have more lenient tolerance on surfaces.
Correct : B. lens antennas
64. Lens antennas are classified into two types. One being fast antenna, the other one is:
Correct : B. delay antenna
65. The antennas which offer high operational bandwidth and the antenna parameters are maintained over a wide range of antennas are called:
Correct : A. wide band antennas
66. High directivity required in RADAR communication is satisfied using this type of antennas:
Correct : B. antenna arrays
67. The terminal impedance of a dipole antenna is 710 Ω. The terminal impedance of the slot antenna given the intrinsic impedance of air is 377 Ω is:
Correct : B. 50 Ω
68. When the separation between two lines that carry the TEM wave approaches λ the wave tends to be radiated.
Correct : A. true
69. An antenna has a field pattern of E (θ) = cos2 θ, θ varies between 0 and 900. Half power beam width of the antenna is:
Correct : B. 660
70. Power radiated from an antenna per unit solid angle is called radiation intensity.
Correct : A. true
71. Antennas are bidirectional devices.
Correct : A. true
72. Which of the following is false regarding Antenna array?
Correct : B. directivity decreases
73. Electrical size of antenna is increased by which of the following?
Correct : A. antenna array
74. For long distance communication, which of the property is mainly necessary for the antenna?
Correct : A. high directivity
75. Which of the following is false about the single antenna for long distance communication?
Correct : B. no side lobes
76. The electrical size of antenna is increased by antenna array to avoid size lobes compared to single antenna.
Correct : A. true
77. Total resultant field obtained by the antenna array is given by which of following?
Correct : A. vector superposition of individual field from the element
78. If the progressive shift in antenna array is equal to zero then it is called
Correct : A. broad side
79. What is the progressive phase shift of the end-fire array?
Correct : C. 180
80. Which of the following statement about antenna array is false?
Correct : B. field pattern is the sum of individual elements in array
81. are used in the final stages of radar and radio transmitters to increase the radiated power level.
Correct : A. power amplifiers
82. Important factors to be considered for power amplifier design are:
Correct : D. all of the mentioned
83. 1 MICROWAVE PASSIVE COMPONENTS: DIRECTIONAL COUPLER, POWER DIVIDER, MAGIC TEE ATTENUATOR, RESONATOR
Correct : A. true
84. Gain of power amplifiers with increase in operating frequency.
Correct : B. decreases
85. amplifiers are linear circuits, where the transistor is biased to conduct over the entire range of the input signal cycle.
Correct : A. class a amplifiers
86. A class B amplifier consists of transistors in order to conduct the input signal over the entire cycle.
Correct : B. 2
87. Power amplifiers in the increasing order of efficiency is:
Correct : A. class a, b, c
88. Behavior of a transistor in power amplifiers is unpredictable at all input signal levels.
Correct : B. false
89. If the output power of an amplifier is 10 V, and the input power supplied to the amplifier is 0.229 V given that the DC voltage used is
Correct : A. 25%
90. If a power amplifier has an output power of 10 W, and an amplifier gain of 16.4 dB, then the input drive power is:
Correct : C. 229 mw
91. GaAs is used in the fabrication of GUNN diodes because:
Correct : D. less forbidden energy gap
92. In a GaAs n-type specimen, the current generated is constant irrespective of the electric filed applied to the specimen.
Correct : B. false
93. When the electric field applied to GaAs specimen is less than the threshold electric field, the current in the material:
Correct : A. increases linearly
94. GaAs is used in fabricating Gunn diode. Gunn diode is:
Correct : A. bulk device
95. The electrodes of a Gunn diode are made of:
Correct : A. molybdenum
96. When either a voltage or current is applied to the terminals of bulk solid state compound GaAs, a differential is developed in that bulk device.
Correct : A. negative resistance
97. The number of modes of operation for n type GaAs is:
Correct : C. four
98. The free electron concentration in N-type GaAs is controlled by:
Correct : A. effective doping
99. The modes of operation of a Gunn diode are illustrated in a plot of voltage applied to the Gunn diode v/s frequency of operation of Gunn diode.
Correct : B. false
100. The mode of operation in which the Gunn diode is not stable is: