# Communications Engineering Exam 8: ECE Pre-Board - Answers

Answers key for the Pre-Board Examinations in Communications Engineering Module 8 composed of previous Board Exams Questions.

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. 2Î¾d

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

61. 1.67

62. 2.8

63. The beamwidth decreases as the gain is increased.

64. 660 kHz

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).

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

### Complete List of Communications Engineering Exams: ECE Pre-Board

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