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ELE3AC
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1992-01-26
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FCC TECHNICIAN Exam Question Pool. Subelement 3AC.
Radio Wave Propagation. 3 Questions.
---------------------------------------------------
3AC 1-1.1 A
What is the ionosphere?
A. That part of the upper atmosphere where enough ions and
free electrons exist to affect radio-wave propagation
B. The boundary between two air masses of different temperature
and humidity, along which radio waves can travel
C. The ball that goes on the top of a mobile whip antenna
D. That part of the atmosphere where weather takes place
3AC 1-1.2 D
What is the region of the outer atmosphere that makes
long-distance radio communications possible as a result of
bending of radio waves?
A. Troposphere
B. Stratosphere
C. Magnetosphere
D. Ionosphere
3AC 1-1.3 C
What type of solar radiation is most responsible for ionization
in the outer atmosphere?
A. Thermal
B. Ionized particle
C. Ultraviolet
D. Microwave
3AC 1-2.1 A
Which ionospheric layer limits daytime radio communications in
the 80-meter band to short distances?
A. D layer
B. F1 layer
C. E layer
D. F2 layer
3AC 1-2.2 B
What is the lowest ionospheric layer?
A. The A layer
B. The D layer
C. The E layer
D. The F layer
3AC 1-3.1 B
What is the lowest region of the ionosphere that is useful for
long-distance radio wave propagation?
A. The D layer
B. The E layer
C. The F1 layer
D. The F2 layer
3AC 1-4.1 D
Which layer of the ionosphere is mainly responsible for
long-distance sky-wave radio communications?
A. D layer
B. E layer
C. F1 layer
D. F2 layer
3AC 1-4.2 B
What are the two distinct sub-layers of the F layer of the
ionosphere during the daytime?
A. Troposphere and stratosphere
B. F1 and F2
C. Electrostatic and electromagnetic
D. D and E
3AC 1-4.3 C
Which two daytime ionospheric layers combine into one layer
at night?
A. E and F1
B. D and E
C. F1 and F2
D. E1 and E2
3AC 2.1 D
Which layer of the ionosphere is most responsible for
absorption of radio signals during daylight hours?
A. The E layer
B. The F1 layer
C. The F2 layer
D. The D layer
3AC 2.2 B
When is ionospheric absorption most pronounced?
A. When tropospheric ducting occurs
B. When radio waves enter the D layer at low angles
C. When radio waves travel to the F layer
D. When a temperature inversion occurs
3AC 2.3 A
During daylight hours, what effect does the D layer of
the ionosphere have on 80-meter radio waves?
A. The D layer absorbs the signals
B. The D layer bends the radio waves out into space
C. The D layer refracts the radio waves back to earth
D. The D layer has little or no effect on 80 meter radio
wave propagation
3AC 2.4 B
What causes ionospheric absorption of radio waves?
A. A lack of D layer ionization
B. D layer ionization
C. The presence of ionized clouds in the E layer
D. Splitting of the F layer
3AC 3.1 D
What is usually the condition of the ionosphere just before
sunrise?
A. Atmospheric attenuation is at a maximum
B. Ionization is at a maximum
C. The E layer is above the F layer
D. Ionization is at a minimum
3AC 3.2 C
At what time of day does maximum ionization of the ionosphere
occur?
A. Dusk
B. Midnight
C. Midday
D. Dawn
3AC 3.3 A
Minimum ionization of the ionosphere occurs daily at what
time?
A. Shortly before dawn
B. Just after noon
C. Just after dusk
D. Shortly before midnight
3AC 3.4 B
When is E layer ionization at a maximum?
A. Dawn
B. Midday
C. Dusk
D. Midnight
3AC 4.1 D
What is the name for the highest radio frequency that will
be refracted back to earth?
A. Lowest usable frequency
B. Optimum working frequency
C. Ultra high frequency
D. Critical frequency
3AC 4.2 C
What causes the maximum usable frequency to vary?
A. Variations in the temperature of the air at ionospheric
levels
B. Upper-atmospheric wind patterns
C. The amount of ultraviolet and other types of radiation
received from the sun
D. Presence of ducting
3AC 4.3 A
What does the term maximum usable frequency refer to?
A. The maximum frequency that allows a radio signal to
reach its destination in a single hop
B. The minimum frequency that allows a radio signal to
reach its destination in a single hop
C. The maximum frequency that allows a radio signal to
be absorbed in the lowest ionospheric layer
D. The minimum frequency that allows a radio signal to
be absorbed in the lowest ionospheric layer
3AC 5.1 C
When two stations are within each other's skip zone on the
frequency being used, what mode of propagation would it be
desirable to use?
A. Ground-wave propagation
B. Sky-wave propagation
C. Scatter-mode propagation
D. Ionospheric-ducting propagation
3AC 5.2 C
You are in contact with a distant station and are operating at a
frequency close to the maximum usable frequency. If the received
signals are weak and somewhat distorted, what type of propagation
are you probably experiencing?
A. Tropospheric ducting
B. Line-of-sight propagation
C. Backscatter propagation
D. Waveguide propagation
3AC 6.1 A
What is the transmission path of a wave that travels
directly from the transmitting antenna to the receiving
antenna called?
A. Line of sight
B. The sky wave
C. The linear wave
D. The plane wave
3AC 6.2 B
How are VHF signals within the range of the visible
horizon propagated?
A. By sky wave
B. By direct wave
C. By plane wave
D. By geometric wave
3AC 7.1 C
Ducting occurs in which region of the atmosphere?
A. F2
B. Ionosphere
C. Troposphere
D. Stratosphere
3AC 7.2 A
What effect does tropospheric bending have on 2-meter radio
waves?
A. It increases the distance over which they can be transmitted
B. It decreases the distance over which they can be transmitted
C. It tends to garble 2-meter phone transmissions
D. It reverses the sideband of 2-meter phone transmissions
3AC 7.3 D
What atmospheric phenomenon causes tropospheric ducting of
radio waves?
A. A very low pressure area
B. An aurora to the north
C. Lightning between the transmitting and receiving station
D. A temperature inversion
3AC 7.4 A
Tropospheric ducting occurs as a result of what phenomenon?
A. A temperature inversion
B. Sun spots
C. An aurora to the north
D. Lightning between the transmitting and receiving station
3AC 7.5 B
What atmospheric phenomenon causes VHF radio waves to
be propagated several hundred miles through stable air
masses over oceans?
A. Presence of a maritime polar air mass
B. A widespread temperature inversion
C. An overcast of cirriform clouds
D. Atmospheric pressure of roughly 29 inches of mercury
or higher
3AC 7.5 D
In what frequency range does tropospheric ducting occur
most often?
A. LF
B. MF
C. HF
D. VHF
--------------------------------------------------
End of Subelement 3AC.