G3 – RADIO WAVE PROPAGATION [3 Exam Questions – 3 Groups] Flashcards
What is the significance of the sunspot number about HF propagation?
A. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies
B. Lower sunspot numbers generally indicate greater probability of sporadic E propagation
C. A zero sunspot number indicates that radio propagation is not possible on any band
D. A zero sunspot number indicates undisturbed conditions
G3A01 (A)
A. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies
What effect does a Sudden Ionospheric Disturbance have on the daytime ionospheric propagation of HF radio waves?
A. It enhances propagation on all HF frequencies
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
G3A02 (B)
B. It disrupts signals on lower frequencies more than those on higher frequencies
Approximately how long does it take the increased ultraviolet and X-ray radiation from solar flares to affect radio propagation on Earth?
A. 28 days
B. 1 to 2 hours
C. 8 minutes
D. 20 to 40 hours
G3A03 (C)
C. 8 minutes
Which of the following are least reliable for long-distance communications during periods of low solar activity?
A. 80 meters and 160 meters
B. 60 meters and 40 meters
C. 30 meters and 20 meters
D. 15 meters, 12 meters, and 10 meters
G3A04 (D)
D. 15 meters, 12 meters, and 10 meters
What is the solar flux index?
A. A measure of the highest frequency that is useful for ionospheric propagation between two points on Earth
B. A count of sunspots that is adjusted for solar emissions
C. Another name for the American sunspot number
D. A measure of solar radiation at 10.7 centimeters wavelength
G3A05 (D)
D. A measure of solar radiation at 10.7 centimeters wavelength
What is a geomagnetic storm?
A. A sudden drop in the solar flux index
B. A thunderstorm that affects radio propagation
C. Ripples in the ionosphere
D. A temporary disturbance in Earth’s magnetosphere
G3A06 (D)
D. A temporary disturbance in Earth’s magnetosphere
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
G3A07 (D)
D. At any point in the solar cycle
Which of the following effects can a geomagnetic storm have on radio propagation?
A. Improved high-latitude HF propagation
B. Degraded high-latitude HF propagation
C. Improved ground wave propagation
D. Degraded ground wave propagation
G3A08 (B)
D. Degraded ground wave propagation
What benefit can high geomagnetic activity have on radio communications?
A. Auroras 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
G3A09 (A)
A. Auroras that can reflect VHF signals
What causes HF propagation conditions to vary periodically in a roughly 28-day cycle?
A. Long term oscillations in the upper atmosphere
B. Cyclic variation in Earth’s radiation belts
C. The sun’s rotation on its axis
D. The position of the moon in its orbit
G3A10 (C)
C. The sun’s rotation on its axis
How long does it take charged particles from coronal mass ejections to affect radio propagation on Earth? A. 28 days B. 14 days C. 4 to 8 minutes D. 20 to 40 hours
G3A11 (D)
D. 20 to 40 hours
What does the K-index indicate?
A. The relative position of sunspots on the surface of the sun
B. The short-term stability of Earth’s magnetic field
C. The stability of the sun’s magnetic field
D. The solar radio flux at Boulder, Colorado
G3A12 (B)
B. The short-term stability of Earth’s magnetic field
What does the A-index indicate?
A. The relative position of sunspots on the surface of the sun
B. The amount of polarization of the sun’s electric field
C. The long-term stability of Earth’s geomagnetic field
D. The solar radio flux at Boulder, Colorado
G3A13 (C)
C. The long-term stability of Earth’s geomagnetic field
How are radio communications usually affected by the charged particles that reach 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
G3A14 (B)
B. HF communications are disturbed
What is a characteristic of skywave signals arriving at your location 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 might be cancelled causing severe attenuation
D. A slightly delayed echo might be heard
G3B01 (D)
D. A slightly delayed echo might be heard
What factors affect the MUF?
A. Path distance and location
B. Time of day and season
C. Solar radiation and ionospheric disturbances
D. All these choices are correct
G3B02 (D)
D. All these choices are correct
Which of the following applies when selecting a frequency 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
G3B03 (A)
A. Select a frequency just below the MUF
What is a reliable way to determine if the MUF is high enough to support skip propagation between your station and a distant location on frequencies between 14 and 30 MHz?
A. Listen for signals from an international beacon in the frequency range you plan to use
B. Send a series of dots on the band and listen for echoes from your signal
C. Check the strength of TV signals from western Europe
D. Check the strength of signals in the MF AM broadcast band
G3B04 (A)
A. Listen for signals from an international beacon in the frequency range you plan to use
What usually happens to radio waves with frequencies below the MUF and above the LUF when they are sent into the ionosphere?
A. They are bent back to Earth
B. They pass through the ionosphere
C. They are amplified by interaction with the ionosphere
D. They are bent and trapped in the ionosphere to circle Earth
G3B05 (A)
A. They are bent back to Earth
What usually happens to radio waves with frequencies below the LUF?
A. They are bent back to 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 Earth
G3B06 (C)
C. They are completely absorbed by the ionosphere
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
G3B07 (A)
A. The Lowest Usable Frequency for communications between two points
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
G3B08 (B)
B. The Maximum Usable Frequency for communications between two points
What is the approximate 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
G3B09 (C)
C. 2,500 miles
What is the approximate 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
G3B10 (B)
B. 1,200 miles
What happens to HF propagation when the LUF exceeds the MUF?
A. No HF radio frequency will support ordinary skywave communications over the path
B. HF communications over the path are enhanced
C. Double hop propagation along the path is more common
D. Propagation over the path on all HF frequencies is enhanced
G3B11 (A)
A. No HF radio frequency will support ordinary skywave communications over the path
Which ionospheric layer is closest to the surface of Earth?
A. The D layer
B. The E layer
C. The F1 layer
D. The F2 layer
G3C01 (A)
A. The D layer
Where on Earth do ionospheric layers reach their maximum height?
A. Where the sun is overhead
B. Where the sun is on the opposite side of Earth
C. Where the sun is rising
D. Where the sun has just set
G3C02 (A)
A. Where the sun is overhead
Why is the F2 region mainly responsible for the longest distance radio wave propagation?
A. Because it is the densest ionospheric layer
B. Because of the Doppler effect
C. Because it is the highest ionospheric region
D. Because of meteor trails at that level
G3C03 (C)
C. Because it is the highest ionospheric region
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 Earth under specific ionospheric conditions
D. The highest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions
G3C04 (D)
D. The highest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions
Why is long-distance communication on the 40-meter, 60-meter, 80-meter, and 160-meter bands more difficult during the day?
A. The F layer absorbs signals at these frequencies during daylight hours
B. The F layer is unstable during daylight hours
C. The D layer absorbs signals at these frequencies during daylight hours
D. The E layer is unstable during daylight hours
G3C05 (C)
C. The D layer absorbs signals at these frequencies during daylight hours
What is a characteristic of HF scatter?
A. Phone signals have high intelligibility
B. Signals have a fluttering sound
C. There are very large, sudden swings in signal strength
D. Scatter propagation occurs only at night
G3C06 (B)
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 different radio wave paths
G3C07 (D)
D. Energy is scattered into the skip zone through several different radio wave paths
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 magnetosphere, 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
G3C08 (A)
A. Only a small part of the signal energy is scattered into the skip zone
What type of propagation allows signals to be heard in the transmitting station’s skip zone?
A. Faraday rotation
B. Scatter
C. Chordal hop
D. Short-path
G3C09 (B)
B. Scatter
What is Near Vertical Incidence Skywave (NVIS) propagation?
A. Propagation near the MUF
B. Short distance MF or HF propagation using high elevation angles
C. Long path HF propagation at sunrise and sunset
D. Double hop propagation near the LUF
G3C10 (B)
B. Short distance MF or HF propagation using high elevation angles
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
G3C11 (D)
D. The D layer
