Below are the answers key for the 100 items set of Practice Examination 8 in Communications Engineering composed of previous Board Exams Questions and cautiously selected questions from various topics in Communications Engineering (Electronics Systems and Technology) that could possibly be given in the board.
1. 0.99
2. Huygen’s principle
3. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency.
4. Phase differences between radio wave components of the same transmission, as experienced at the receiving station.
5. Radio waves may be bent.
6. Tropospheric ducting
7. The ratio between the deviation of a frequency modulated signal and the modulating frequency.
8. knife-edge diffraction
9. 60 cm
10. Radiation resistance plus ohmic resistance
11. A wave consisting of an electric field and a magnetic field at right angles to each other
12. 300 – 3000 MHz
13. 90 degrees
14. 40 km
15. The electric field is parallel to the earth.
16. The electric field rotates
17. 72 km
18. 36 meters high
19. Microwave
20. Salt water
21. 300 ohms
22. Frequency hopping
23. 0.66
24. 6 watts
25. Dielectrics in the line
26. Direct sequence
27. 30 to 300 kHz
28. 3 MHz to 30 MHz
29. 700 MHz
30. D
31. lowest, highest
32. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
33. Velocity factor
34. RF energy moves slower along the coaxial cable
35. 3.51 meters
36. Optimum useable frequency (OUF).
37. 1.66
38. 300 MHz to 3 GHz
39. 4250 MHz to 4350 MHz
40. A frequency modulated continuous wave
41. Is the same direction as the electrostatic field of the antenna.
42. 1 watt
43. When comparing the gains of directional antennas
44. vertical, horizontal
45. Gain increases 6 dB
46. 118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz)
47. A fading effect caused by phase differences between radio wave components of the same transmission, as experienced at the receiving station
48.1.5
49. 2ξd
50. Space wave
51. 100 Hz
52. Both VLF and LF
53. Virtual height
54. 300 km
55. Flexible coaxial line
56. ½ to 2/3
57. 100 x 103 m/s
58. 0.25
59. 2.76 x 10-9 S/m
60. 150 Ω
61. 1.67
62. 2.8
63. The beamwidth decreases as the gain is increased.
64. 660 kHz
65. 2500 Ω
66. 352 m3
67. 0.8 – 1.2 sec.
68. 99.7 MHz
69. 999.8 kHz, 1000 kHz, and 1000.2 kHz
70. IF amplifier
71. Space noise
72. 500 Hz
73. Between 15 to 60
74. 0.54
75. 10,800
76. 2.089
77. The standing wave ratio is one.
78. The power traveling from the transmitter to the antenna.
79. The American National Standards Institute (ANSI).
80. internal receiver noise.
81. final RF stage
82. Midday
83. ± 12 KHz
84. Goniometer
85. GMDSS
86. Helical
87. an impedance mismatch between the load and the line.
88. Calorimeter
89. . Dominant mode
90. Doppler effect
91. 1.35 cm and 1.7 mm
92. 5 mm and 2.5 mm
93. 4130 km
94. F2 layer
95. distance-to-reuse ratio (D/R)
96. Frequency agility
97. Hexagon
98. 6
99. 10-12 W/m2
100. 5150 m/s
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