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42 Cards in this Set

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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
wavelength λ in metres = 300 Mm/s divided by the frequency in MHz
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.
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.
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.
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.
d = √17h
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.
d = √17h
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.
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.
d²/17 = h
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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
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
42] Ducts often form over:

a} Dry and arid deserts

b} Cold arctic regions

c} Highly industrialized regions

d} Water
d} Water