All 37 Ham Radio General Class questions for G3 Radio Wave Propagation with the correct answers marked, from the official 2023-2027 question pool. Test yourself with the free practice exam.
G3A01
How does a higher sunspot number affect 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
G3A02
What effect does a sudden ionospheric disturbance have on the daytime ionospheric propagation?
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
G3A03
Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth?
A. 28 days
B. 1 to 2 hours
C. 8 minutes ✓
D. 20 to 40 hours
G3A04
Which of the following are the least reliable bands 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 ✓
G3A05
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 with a wavelength of 10.7 centimeters ✓
G3A06
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 geomagnetic force
D. A temporary disturbance in Earth’s geomagnetic field ✓
G3A07
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
C. Only at the minimum point
D. At any point ✓
G3A08
How can a geomagnetic storm affect HF propagation?
A. Improve high-latitude HF propagation
B. Degrade ground wave propagation
C. Improve ground wave propagation
D. Degrade high-latitude HF propagation ✓
G3A09
How can high geomagnetic activity benefit radio communications?
A. Creates auroras that can reflect VHF signals ✓
B. Increases signal strength for HF signals passing through the polar regions
C. Improve HF long path propagation
D. Reduce long delayed echoes
G3A10
What causes HF propagation conditions to vary periodically in a 26- to 28-day cycle?
A. Long term oscillations in the upper atmosphere
B. Cyclic variation in Earth’s radiation belts
C. Rotation of the Sun’s surface layers around its axis ✓
D. The position of the Moon in its orbit
G3A11
How long does it take a coronal mass ejection to affect radio propagation on Earth?
A. 28 days
B. 14 days
C. 4 to 8 minutes
D. 15 hours to several days ✓
G3A12
What does the K-index measure?
A. The relative position of sunspots on the surface of the Sun
B. The short-term stability of Earth’s geomagnetic field ✓
C. The short-term stability of the Sun’s magnetic field
D. The solar radio flux at Boulder, Colorado
G3A13
What does the A-index measure?
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
G3A14
How is long distance radio communication usually affected by the charged particles that reach Earth from solar coronal holes?
A. HF communication is improved
B. HF communication is disturbed ✓
C. VHF/UHF ducting is improved
D. VHF/UHF ducting is disturbed
G3B01
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 ✓
G3B02
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 ✓
G3B03
Which frequency will have the least attenuation for long-distance skip propagation?
A. Just below the MUF ✓
B. Just above the LUF
C. Just below the critical frequency
D. Just above the critical frequency
G3B04
Which of the following is a way to determine current propagation on a desired band from your station?
A. Use a network of automated receiving stations on the internet to see where your transmissions are being received ✓
B. Check the A-index
C. Send a series of dots and listen for echoes
D. All these choices are correct
G3B05
How does the ionosphere affect radio waves with frequencies below the MUF and above the LUF?
A. They are refracted back to Earth ✓
B. They pass through the ionosphere
C. They are amplified by interaction with the ionosphere
D. They are refracted and trapped in the ionosphere to circle Earth
G3B06
What usually happens to radio waves with frequencies below the LUF?
A. They are refracted back to Earth
B. They pass through the ionosphere
C. They are attenuated before reaching the destination ✓
D. They are refracted and trapped in the ionosphere to circle Earth
G3B07
What does LUF stand for?
A. The Lowest Usable Frequency for communications between two specific points ✓
B. The Lowest Usable Frequency for communications to any point outside a 100-mile radius
C. The Lowest Usable Frequency during a 24-hour period
D. The Lowest Usable Frequency during the past 60 minutes
G3B08
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
G3B09
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the F2 region?
A. 180 miles
B. 1,200 miles
C. 2,500 miles ✓
D. 12,000 miles
G3B10
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the E region?
A. 180 miles
B. 1,200 miles ✓
C. 2,500 miles
D. 12,000 miles
G3B11
What happens to HF propagation when the LUF exceeds the MUF?
A. Propagation via ordinary skywave communications is not possible over that 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
G3B12
Which of the following is typical of the lower HF frequencies during the summer?
A. Poor propagation at any time of day
B. World-wide propagation during daylight hours
C. Heavy distortion on signals due to photon absorption
D. High levels of atmospheric noise or static ✓
G3C01
Which ionospheric region is closest to the surface of Earth?
A. The D region ✓
B. The E region
C. The F1 region
D. The F2 region
G3C02
What is meant by the term “critical frequency” at a given incidence angle?
A. The highest frequency which is refracted back to Earth ✓
B. The lowest frequency which is refracted back to Earth
C. The frequency at which the signal-to-noise ratio approaches unity
D. The frequency at which the signal-to-noise ratio is 6 dB
G3C03
Why is skip propagation via the F2 region longer than that via the other ionospheric regions?
A. Because it is the densest
B. Because of the Doppler effect
C. Because it is the highest ✓
D. Because of temperature inversions
G3C04
What does the term “critical angle” mean, as applied to 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 ✓
G3C05
Why is long-distance communication on the 40-, 60-, 80-, and 160-meter bands more difficult during the day?
A. The F region absorbs signals at these frequencies during daylight hours
B. The F region is unstable during daylight hours
C. The D region absorbs signals at these frequencies during daylight hours ✓
D. The E region is unstable during daylight hours
G3C06
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
G3C07
What makes HF scatter signals often sound distorted?
A. The ionospheric region 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 paths ✓
G3C08
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 via ground waves, which absorb most of the signal energy
D. Propagation is via ducts in the F region, which absorb most of the energy
G3C09
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
G3C10
What is near vertical incidence skywave (NVIS) propagation?
A. Propagation near the MUF
B. Short distance MF or HF propagation at high elevation angles ✓
C. Long path HF propagation at sunrise and sunset
D. Double hop propagation near the LUF
G3C11
Which ionospheric region is the most absorbent of signals below 10 MHz during daylight hours?
A. The F2 region
B. The F1 region
C. The E region
D. The D region ✓