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42 Cards in this Set
- Front
- Back
- 3rd side (hint)
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1] What is a selective fading effect?
a} A fading effect caused by small changes in beam heading at the receiving station. b} A fading effect caused by phase differences between radio wave components of the same transmission, as experienced at the receiving station. c} A fading effect caused by large changes in the height of the ionosphere, as experienced at the receiving station. d} A fading effect caused by time differences between the receiving and transmitting stations. |
b} A fading effect caused by phase differences between radio
wave components of the same transmission, as experienced at the receiving station. |
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2] What is the propagation effect called when phase
differences between radio wave components of the same transmission are experienced at the recovery station? a} Faraday rotation. b} Diversity reception. c} Selective fading. d} Phase shift. |
c} Selective fading.
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3] What is the major cause of selective fading?
a} Small changes in beam heading at the receiving station. b} Large changes in the height of the ionosphere, as experienced at the receiving station. c} Time differences between the receiving and transmitting stations. d} Phase differences between radio wave components of the same transmission, as experienced at the receiving station. |
d} Phase differences between radio wave components of the same
transmission, as experienced at the receiving station. |
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4] Which emission modes suffer the most from selective fading?
a} CW and SSB. b} FM and double sideband AM. c} SSB and image. d} SSTV and CW. |
b} FM and double sideband AM.
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5] How does the bandwidth of the transmitted signal affect
selective fading? a} It is more pronounced at wide bandwidths. b} It is more pronounced at narrow bandwidths. c} It is equally pronounced at both narrow and wide bandwidths. d} The receiver bandwidth determines the selective fading effect |
a} It is more pronounced at wide bandwidths.
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6] What phenomenon causes the radio-path horizon distance to
exceed the geometric horizon? a} E-layer skip. b} D-layer skip. c} Auroral skip. d} Radio waves may be bent. |
d} Radio waves may be bent.
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7] How much farther does the radio-path horizon distance
exceed the geometric horizon? a} By approximately 15% of the distance. b} By approximately twice the distance. c} By approximately one-half the distance. d} By approximately four times the distance. |
a} By approximately 15% of the distance.
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8] What propagation condition is usually indicated when a VHF
signal is received from a station over 500 miles away? a} D-layer absorption. b} Faraday rotation. c} Tropospheric ducting. d} Moonbounce. |
c} Tropospheric ducting.
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9] What happens to a radio wave as it travels in space and
collides with other particles? a} Kinetic energy is given up by the radio wave. b} Kinetic energy is gained by the radio wave. c} Aurora is created. d} Nothing happens since radio waves have no physical substance. |
a} Kinetic energy is given up by the radio wave.
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10] When the earth's atmosphere is struck by a meteor, a
cylindrical region of free electrons is formed at what layer of the ionosphere? a} The F1 layer. b} The E layer. c} The F2 layer. d} The D layer. |
b} The E layer.
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11] What is transequatorial propagation?
a} Propagation between two points at approximately the same distance north and south of the magnetic equator. b} Propagation between two points on the magnetic equator. c} Propagation between two continents by way of ducts along the magnetic equator. d} Propagation between any two stations at the same latitude. |
a} Propagation between two points at approximately the same
distance north and south of the magnetic equator. |
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12] What is the maximum range for signals using transequatorial propagation?
a} About 1,000 miles. b} About 2,500 miles. c} About 5,000 miles. d} About 7,500 miles. |
c} About 5,000 miles.
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13] What is the best time of day for transequatorial propagation?
a} Morning. b} Noon. c} Afternoon or early evening. d} Transequatorial propagation only works at night |
c} Afternoon or early evening.
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14] What is knife-edge diffraction?
a} Allows normally line-of-sight signals to bend around sharp edges, mountain ridges, buildings and other obstructions. b} Arcing in sharp bends of conductors. c} Phase angle image rejection. d} Line-of-sight signals causing distortion to other signals |
a} Allows normally line-of-sight signals to bend around sharp
edges, mountain ridges, buildings and other obstructions. |
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15] The bending of radio waves passing over the top of a
mountain range that disperses a weak portion of the signal behind the mountain is: a} Eddy-current phase effect. b} Knife-edge diffraction. c} Shadowing. d} Mirror refraction effect. |
b} Knife-edge diffraction.
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16] Knife-edge diffraction:
a} Is the bending of UHF frequency radio waves around a building, mountain or obstruction. b} Causes the velocity of wave propagation to be different from original wave. c} Is the bending of UHF frequency radio waves around a building, mountain or obstruction and causes the velocity of wave propagation to be different from original wave. d} Attenuates UHF signals. |
c} Is the bending of UHF frequency radio waves around a building, mountain or obstruction and causes the velocity of wave propagation to be different from original wave.
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17] If the elapsed time for a radar echo is 62 microseconds
what is the distance in nautical miles to the object? a} 5 nautical miles. b} 87 nautical miles. c} 37 nautical miles. d} 11.5 nautical miles. |
a} 5 nautical miles.
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18] What is the wavelength of a signal at 500 MHz?
a} 0.062 cm. b} 6 meters. c} 60 cm. d} 60 meters. |
c} 60 cm.
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wavelength λ in metres = 300 Mm/s divided by the frequency in MHz
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19] The radar range in nautical miles to an object can be
found by measuring the elapsed time during a radar pulse and dividing this quantity by: a} 0.87 seconds. b} 1.15 microseconds. c} 12.36 microseconds. d} 1.73 microseconds |
c} 12.36 microseconds.
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20] The band of frequencies least susceptible to atmospheric
noise and interference is: a} 30 - 300 kHz. b} 300 - 3000 kHz. c} 3 - 30 MHz. d} 300 - 3000 MHz. |
d} 300 - 3000 MHz.
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21] What is the relationship in degrees of the electrostatic
and electromagnetic fields of an antenna? a} 0 degrees. b} 45 degrees. c} 90 degrees. d} 180 degrees. |
c} 90 degrees.
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22] For a space wave transmission, the radio horizon
distance of a transmitting antenna with a height of 100 meters is approximately : a} 10 km. b} 40 km. c} 100 km. d} 400 km. |
b} 40 km.
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d = √17h
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23] For a space wave transmission, the radio horizon
distance of a receiving antenna with a height of 64 meters is approximately : a} 8 km. b} 32 km. c} 64 km. d} 256 km. |
b} 32 km.
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d = √17h
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24] If a transmitting antenna is 100 meters high and a
separate receiving antenna is 64 meters high, what is the maximum space wave communication distance possible between them? a} 18 km. b} 72 km. c} 164 km. d} 656 km. |
b} 72 km.
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25] A receiver is located 64 km from a space wave
transmitting antenna that is 100 meters high. Find the required height of the receiving antenna. a} 36 meters high. b} 64 meters high. c} 100 meters high. d} 182.25 meters high. |
a} 36 meters high.
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d²/17 = h
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26] Which of the following is not one of the natural ways a
radio wave may travel from transmitter to receiver? a} Ground wave. b} Micro wave. c} Sky wave. d} Space wave. |
b} Micro wave.
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27] Which of the following terrain types permits a ground
wave to travel the farthest? a} Salt water. b} Fresh water. c} Sandy. d} Rocky. |
a} Salt water.
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28] Which of the following frequency bands is best suited
for ground wave propagation? a} 30 kHz to 300 kHz. b} 300 kHz to 3 MHz. c} 3 MHz to 30 MHz. d} 30 MHz to 300 MHz. |
a} 30 kHz to 300 kHz.
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29] Which of the following frequency bands is best suited
for sky wave propagation? a} 30 kHz to 300 kHz. b} 3 MHz to 30 MHz. c} 30 MHz to 300 MHz. d} 3 GHz to 30 GHz. |
b} 3 MHz to 30 MHz.
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30] Which of the following layers of the Ionosphere has no
effect on sky wave propagation during the hours of darkness? a} D. b} E. c} F. d} None of these. |
a} D.
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31] Which of the following least affects refraction of sky
waves? a} Frequency of the radio wave. b} Density of the ionized layer. c} Angle at which the radio wave enters the ionosphere. d} Geographical variations. |
d} Geographical variations.
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32] The area that lies between the outer limit of the ground
wave range and the inner edge of energy returned from the Ionosphere is called : a} The critical angle. b} The skip zone. c} The skip distance. d} The shadow. |
b} The skip zone.
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33] Skip Distance can be maximized by using the ____
radiation angle possible and the ____ frequency that will be refracted at that angle. a} Lowest, lowest. b} Lowest, highest. c} Highest, lowest. d} Highest, highest. |
b} Lowest, highest.
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34] To obtain the most reliable sky wave propagation the
____ should be used. a} Lowest useable frequency (LUF). b} Maximum useable frequency (MUF). c} Optimum useable frequency (OUF). d} Critical frequency. |
c} Optimum useable frequency (OUF).
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35] Tropospheric scatter is a method of sky wave propagation
for which of the following frequency bands? a} 300 kHz to 3 MHz. b} 3 MHz to 30 MHz. c} 30 MHz to 300 MHz. d} 300 MHz to 3 GHz. |
d} 300 MHz to 3 GHz.
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36] Which of the following methods are used for diversity
reception to overcome the effects of tropospheric scattering of a sky wave? a} Frequency diversity. b} Phase diversity. c} Amplitude diversity. d} Critical diversity. |
a} Frequency diversity.
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37] Which of the following will not significantly reduce the
effects of fading? a} Use an antenna with a good front to back ratio. b} Use an antenna with a sharp frontal lobe. c} Use an antenna with a minimum number of spurious side and back lobes. d} Use an antenna with good omni directional pattern. |
d} Use an antenna with good omni directional pattern.
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38] Which of the following terms is not used to define
ionospheric variations? a} Seasonal variations. b} Geographical variations. c} Cyclical variations. d} Tropospheric scatter variations. |
d} Tropospheric scatter variations.
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39] The polarization of a radio wave :
a} Is perpendicular to the electrostatic field of the antenna. b} Is the same direction as the electrostatic field of the antenna. c} Is the same direction as the magnetic field of the antenna. d} Is perpendicular to both the electrostatic and magnetic. fields of the antenna |
b} Is the same direction as the electrostatic field of the
antenna. |
Radar takes 6.2 microseconds to travel 1 nautical mile.
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40] The direction of propagation of a radio wave is ____ to
the electrostatic field of the antenna and ____ to the magnetic field of the antenna. a} Parallel, parallel b} Parallel, perpendicular c} Perpendicular, parallel d} Perpendicular, perpendicular |
d} Perpendicular, perpendicular
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41] Most AM broadcasts employ ____ polarization while most
FM broadcasts employ ____ polarization of the radio wave. a} Vertical, vertical b} Vertical, horizontal c} Horizontal, vertical d} Horizontal, horizontal |
b} Vertical, horizontal
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42] Ducts often form over:
a} Dry and arid deserts b} Cold arctic regions c} Highly industrialized regions d} Water |
d} Water
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