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ELE4AC
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1992-01-26
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FCC ADVANCED Exam Question Pool. Subelement 4AC.
Radio Wave Propagation. 2 Questions.
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4AC 1.1 C
What is a sporadic-E condition?
A. Variations in E-layer height caused by sunspot variations
B. A brief increase in VHF signal levels from meteor trails at E-layer
height
C. Patches of dense ionization at E-layer height
D. Partial tropospheric ducting at E-layer height
4AC 1.2 D
What is the propagation condition called where scattered patches of
relatively dense ionization develop seasonally at E layer heights?
A. Auroral propagation
B. Ducting
C. Scatter
D. Sporadic-E
4AC 1.3 A
In what region of the world is sporadic-E most prevalent?
A. The equatorial regions
B. The arctic regions
C. The northern hemisphere
D. The polar regions
4AC 1.4 B
On which amateur frequency band is the extended distant propagation effect
of sporadic-E most often observed?
A. 2 meters
B. 6 meters
C. 20 meters
D. 160 meters
4AC 1.5 A
What appears to be the major cause of the sporadic-E condition?
A. Wind shear
B. Sunspots
C. Temperature inversions
D. Meteors
4AC 2.1 B
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
4AC 2.2 C
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
4AC 2.3 D
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
4AC 2.4 B
Which emission modes suffer the most from selective fading?
A. CW and SSB
B. FM and double sideband AM
C. SSB and AMTOR
D. SSTV and CW
4AC 2.5 A
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
4AC 3.1 D
What effect does auroral activity have upon radio communications?
A. The readability of SSB signals increases
B. FM communications are clearer
C. CW signals have a clearer tone
D. CW signals have a fluttery tone
4AC 3.2 C
What is the cause of auroral activity?
A. A high sunspot level
B. A low sunspot level
C. The emission of charged particles from the sun
D. Meteor showers concentrated in the northern latitudes
4AC 3.3 B
In the northern hemisphere, in which direction should a directional antenna
be pointed to take maximum advantage of auroral propagation?
A. South
B. North
C. East
D. West
4AC 3.4 D
Where in the ionosphere does auroral activity occur?
A. At F-layer height
B. In the equatorial band
C. At D-layer height
D. At E-layer height
4AC 3.5 A
Which emission modes are best for auroral propagation?
A. CW and SSB
B. SSB and FM
C. FM and CW
D. RTTY and AM
4AC 4.1 D
Why does the radio-path horizon distance exceed the geometric horizon?
A. E-layer skip
B. D-layer skip
C. Auroral skip
D. Radio waves may be bent
4AC 4.2 A
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
4AC 4.3 B
To what distance is VHF propagation ordinarily limited?
A. Approximately 1000 miles
B. Approximately 500 miles
C. Approximately 1500 miles
D. Approximately 2000 miles
4AC 4.4 C
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
4AC 4.5 A
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
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End of Subelement 4AC.