SUBELEMENT G3 - RADIO WAVE PROPAGATION [3 Exam Questions - 3 Groups]
G3A - Sunspots and solar radiation; ionospheric disturbances; propagation forecasting and indices
G3A01 (A)
What can be done at an amateur station to continue communications during a sudden ionospheric disturbance?
A. Try a higher frequency
B. Try the other sideband
C. Try a different antenna polarization
D. Try a different frequency shift
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G3A02 (B)
What effect does a Sudden Ionospheric Disturbance (SID) have on the daytime ionospheric propagation of HF radio waves?
A. It disrupts higher-latitude paths more than lower-latitude paths
B. It disrupts signals on lower frequencies more than those on higher frequencies
C. It disrupts communications via satellite more than direct communications
D. None, because only areas on the night side of the Earth are affected
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G3A03 (C)
How long does it take the increased ultraviolet and X-ray radiation from solar flares to affect radio-wave propagation on the Earth?
A. 28 days
B. Several hours depending on the position of the Earth in its orbit
C. Approximately 8 minutes
D. 20 to 40 hours after the radiation reaches the Earth
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G3A04 (B)
What is measured by the solar flux index?
A. The density of the sun's magnetic field
B. The radio energy emitted by the sun
C. The number of sunspots on the side of the sun facing the Earth
D. A measure of the tilt of the Earth's ionosphere on the side toward the sun
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G3A05 (D)
What is the solar-flux index?
A. A measure of the highest frequency that is useful for ionospheric propagation
between two points on the Earth
B. A count of sunspots which is adjusted for solar emissions
C. Another name for the American sunspot number
D. A measure of solar activity at 10.7 cm
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G3A06 (D)
What is a geomagnetic disturbance?
A. A sudden drop in the solar-flux index
B. A shifting of the Earth's magnetic pole
C. Ripples in the ionosphere
D. A significant change in the Earth's magnetic field over a short period of time
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G3A07 (A)
Which latitudes have propagation paths that are more sensitive to geomagnetic
disturbances?
A. Those greater than 45 degrees North or South latitude
B. Those between 5 and 45 degrees North or South latitude
C. Those at or very near to the equator
D. All paths are affected equally
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G3A08 (B)
What can be an effect of a geomagnetic storm on radio-wave propagation?
A. Improved high-latitude HF propagation
B. Degraded high-latitude HF propagation
C. Improved ground-wave propagation
D. Improved chances of UHF ducting
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G3A09 (C)
What is the effect on radio communications when sunspot numbers are high?
A. High-frequency radio signals become weak and distorted
B. Frequencies above 300 MHz become usable for long-distance communication
C. Long-distance communication in the upper HF and lower VHF range is enhanced
D. Long-distance communication in the upper HF and lower VHF range is diminished
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G3A10 (A)
What is the sunspot number?
A. A measure of solar activity based on counting sunspots and sunspot groups
B. A 3 digit identifier which is used to track individual sunspots
C. A measure of the radio flux from the sun measured at 10.7 cm
D. A measure of the sunspot count based on radio flux measurements
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G3A11 (D)
How long is the typical sunspot cycle?
A. Approximately 8 minutes
B. Between 20 and 40 hours
C. Approximately 28 days
D. Approximately 11 years
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G3A12 (B)
What is the K-index?
A. An index of the relative position of sunspots on the surface of the sun
B. A measure of the short term stability of the Earth’s magnetic field
C. A measure of the stability of the sun's magnetic field
D. An index of solar radio flux measured at Boulder, Colorado
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G3A13 (C)
What is the A-index?
A. An index of the relative position of sunspots on the surface of the sun
B. The amount of polarization of the sun's electric field
C. An indicator of the long term stability of the Earth’s geomagnetic field
D. An index of solar radio flux measured at Boulder, Colorado
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G3A14 (B)
How are radio communications usually affected by the charged particles that reach the Earth from solar coronal holes?
A. HF communications are improved
B. HF communications are disturbed
C. VHF/UHF ducting is improved
D. VHF/UHF ducting is disturbed
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G3A15 (D)
How long does it take charged particles from Coronal Mass Ejections to affect radio-wave propagation on the Earth?
A. 28 days
B. 14 days
C. The effect is instantaneous
D. 20 to 40 hours
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G3A16 (A)
What is a possible benefit to radio communications resulting from periods of high geomagnetic activity?
A. Aurora that can reflect VHF signals
B. Higher signal strength for HF signals passing through the polar regions
C. Improved HF long path propagation
D. Reduced long delayed echoes
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G3A17 (D)
At what point in the solar cycle does the 20 meter band usually support worldwide propagation during daylight hours?
A. At the summer solstice
B. Only at the maximum point of the solar cycle
C. Only at the minimum point of the solar cycle
D. At any point in the solar cycle
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G3A18 (C)
If the HF radio-wave propagation (skip) is generally good on the 24-MHz and 28-MHz bands for several days, when might you expect a similar condition to occur?
A. 7 days later
B. 14 days later
C. 28 days later
D. 90 days later
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G3A19 (D)
Which frequencies are least reliable for long distance communications during periods of low solar activity?
A. Frequencies below 3.5 MHz
B. Frequencies near 3.5 MHz
C. Frequencies at or above 10 MHz
D. Frequencies above 20 MHz
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G3B - Maximum Usable Frequency; Lowest Usable Frequency; propagation "hops"
G3B01 (B)
Which band should offer the best chance for a successful contact if the maximum usable frequency (MUF) between the two stations is 22 MHz?
A. 10 meters
B. 15 meters
C. 20 meters
D. 40 meters
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G3B02 (C)
Which band should offer the best chance for a successful contact if the maximum usable frequency (MUF) between the two stations is 16 MHz?
A. 80 meters
B. 40 meters
C. 20 meters
D. 2 meters
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G3B03 (A)
Which of the following guidelines should be selected for lowest attenuation when transmitting on HF?
A. Select a frequency just below the MUF
B. Select a frequency just above the LUF
C. Select a frequency just below the critical frequency
D. Select a frequency just above the critical frequency
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G3B04 (A)
What is a reliable way to determine if the maximum usable frequency (MUF) is high enough to support 28-MHz propagation between your station and Western Europe?
A. Listen for signals on a 28 MHz international beacon
B. Send a series of dots on the 28 MHz band and listen for echoes from your signal
C. Check the strength of TV signals from Western Europe
D. Listen to WWV propagation signals on the 28 MHz band
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G3B05 (A)
What usually happens to radio waves with frequencies below the maximum usable frequency (MUF) when they are sent into the ionosphere?
A. They are bent back to the Earth
B. They pass through the ionosphere
C. They are completely absorbed by the ionosphere
D. They are bent and trapped in the ionosphere to circle the Earth
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G3B06 (C)
What usually happens to radio waves with frequencies below the lowest usable frequency (LUF)?
A. They are bent back to the Earth
B. They pass through the ionosphere
C. They are completely absorbed by the ionosphere
D. They are bent and trapped in the ionosphere to circle the Earth
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G3B07 (A)
What does LUF stand for?
A. The Lowest Usable Frequency for communications between two points
B. The Longest Universal Function for communications between two points
C. The Lowest Usable Frequency during a 24 hour period
D. The Longest Universal Function during a 24 hour period
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G3B08 (B)
What does MUF stand for?
A. The Minimum Usable Frequency for communications between two points
B. The Maximum Usable Frequency for communications between two points
C. The Minimum Usable Frequency during a 24 hour period
D. The Maximum Usable Frequency during a 24 hour period
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G3B09 (C)
What is the maximum distance along the Earth's surface that is normally covered in one hop using the F2 region?
A. 180 miles
B. 1,200 miles
C. 2,500 miles
D. 12,000 miles
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G3B10 (B)
What is the maximum distance along the Earth's surface that is normally covered in one hop using the E region?
A. 180 miles
B. 1,200 miles
C. 2,500 miles
D. 12,000 miles
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G3B11 (A)
What happens to HF propagation when the lowest usable frequency (LUF) exceeds the maximum usable frequency (MUF)?
A. No HF radio frequency will support communications over the path
B. HF communications over the path are enhanced at the frequency where the LUF and
MUF are the same
C. Double hop propagation along the path is more common
D. Propagation over the path on all HF frequencies is enhanced
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G3B12 (D)
What factors affect the maximum usable frequency (MUF)?
A. Path distance and location
B. Time of day and season
C. Solar radiation and ionospheric disturbance
D. All of these choices are correct
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G3B13 (D)
How might a sky-wave signal sound if it arrives at your receiver by both short path and long path propagation?
A. Periodic fading approximately every 10 seconds
B. Signal strength increased by 3 dB
C. The signal will be cancelled causing severe attenuation
D. A well-defined echo can be heard
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G3B14 (A)
Which of the following is a good indicator of the possibility of sky-wave propagation on the 6 meter band?
A. Short hop sky-wave propagation on the 10 meter band
B. Long hop sky-wave propagation on the 10 meter band
C. Severe attenuation of signals on the 10 meter band
D. Long delayed echoes on the 10 meter band
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G3C - Ionospheric layers; critical angle and frequency; HF scatter; Near Vertical Incidence Sky waves
G3C01 (A)
Which of the following ionospheric layers is closest to the surface of the Earth?
A. The D layer
B. The E layer
C. The F1 layer
D. The F2 layer
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G3C02 (A)
When can the F2 region be expected to reach its maximum height at your location?
A. At noon during the summer
B. At midnight during the summer
C. At dusk in the spring and fall
D. At noon during the winter
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G3C03 (C)
Why is the F2 region mainly responsible for the longest distance radio wave propagation?
A. Because it is the densest ionospheric layer
B. Because it does not absorb radio waves as much as other ionospheric regions
C. Because it is the highest ionospheric region
D. All of these choices are correct
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G3C04 (D)
What does the term “critical angle” mean as used in radio wave propagation?
A. The long path azimuth of a distant station
B. The short path azimuth of a distant station
C. The lowest takeoff angle that will return a radio wave to the Earth under specific
ionospheric conditions
D. The highest takeoff angle that will return a radio wave to the Earth under
specific ionospheric conditions
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G3C05 (C)
Why is long distance communication on the 40, 60, 80 and 160 meter bands more difficult during the day?
A. The F layer absorbs these frequencies during daylight hours
B. The F layer is unstable during daylight hours
C. The D layer absorbs these frequencies during daylight hours
D. The E layer is unstable during daylight hours
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G3C06 (B)
What is a characteristic of HF scatter signals?
A. They have high intelligibility
B. They have a wavering sound
C. They have very large swings in signal strength
D. All of these choices are correct
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G3C07 (D)
What makes HF scatter signals often sound distorted?
A. The ionospheric layer involved is unstable
B. Ground waves are absorbing much of the signal
C. The E-region is not present
D. Energy is scattered into the skip zone through several radio wave paths
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G3C08 (A)
Why are HF scatter signals in the skip zone usually weak?
A. Only a small part of the signal energy is scattered into the skip zone
B. Signals are scattered from the troposphere which is not a good reflector
C. Propagation is through ground waves which absorb most of the signal energy
D. Propagations is through ducts in F region which absorb most of the energy
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G3C09 (B)
What type of radio wave propagation allows a signal to be detected at a distance too far for ground wave propagation but too near for normal sky wave propagation?
A. Ground wave
B. Scatter
C. Sporadic-E skip
D. Short-path skip
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G3C10 (D)
Which of the following might be an indication that signals heard on the HF bands are being received via scatter propagation?
A. The communication is during a sunspot maximum
B. The communication is during a sudden ionospheric disturbance
C. The signal is heard on a frequency below the maximum usable frequency
D. The signal is heard on a frequency above the maximum usable frequency
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G3C11 (A)
Which of the following is true about ionospheric absorption near the maximum usable frequency (MUF)?
A. Absorption will be minimum
B. Absorption is greater for vertically polarized waves
C. Absorption approaches maximum
D. Absorption is greater for horizontally polarized waves
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G3C12 (D)
Which ionospheric layer is the most absorbent of long skip signals during daylight hours on frequencies below 10 MHz?
A. The F2 layer
B. The F1 layer
C. The E layer
D. The D layer
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G3C13 (B)
What is Near Vertical Incidence Sky-wave (NVIS) propagation?
A. Propagation near the MUF
B. Short distance HF propagation using high elevation angles
C. Long path HF propagation at sunrise and sunset
D. Double hop propagation near the LUF
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G3C14 (B)
Which of the following antennas will be most effective for skip communications on 40 meters during the day?
A. A vertical antenna
B. A horizontal dipole placed between 1/8 and 1/4 wavelength above the ground
C. A left-hand circularly polarized antenna
D. A right-hand circularly polarized antenna
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