G3 Questions
34 questions in this subelement. Click any question ID for more details.
Answer: B
What effect does a sudden ionospheric disturbance have on the daytime ionospheric propagation?
AIt enhances propagation on all HF frequencies
BIt disrupts signals on lower frequencies more than those on higher frequencies
CIt disrupts communications via satellite more than direct communications
DNone, because only areas on the night side of the Earth are affected
Answer: C
Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth?
A28 days
B1 to 2 hours
C8 minutes
D20 to 40 hours
Answer: D
Which of the following are the least reliable bands for long-distance communications during periods of low solar activity?
A80 meters and 160 meters
B60 meters and 40 meters
C30 meters and 20 meters
D15 meters, 12 meters, and 10 meters
Answer: D
What is the solar flux index?
AA measure of the highest frequency that is useful for ionospheric propagation between two points on Earth
BA count of sunspots that is adjusted for solar emissions
CAnother name for the American sunspot number
DA measure of solar radiation with a wavelength of 10.7 centimeters
Answer: D
What is a geomagnetic storm?
AA sudden drop in the solar flux index
BA thunderstorm that affects radio propagation
CRipples in the geomagnetic force
DA temporary disturbance in Earth’s geomagnetic field
Answer: D
At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight hours?
AAt the summer solstice
BOnly at the maximum point
COnly at the minimum point
DAt any point
Answer: D
How can a geomagnetic storm affect HF propagation?
AImprove high-latitude HF propagation
BDegrade ground wave propagation
CImprove ground wave propagation
DDegrade high-latitude HF propagation
Answer: A
How can high geomagnetic activity benefit radio communications?
ACreates auroras that can reflect VHF signals
BIncreases signal strength for HF signals passing through the polar regions
CImprove HF long path propagation
DReduce long delayed echoes
Answer: C
What causes HF propagation conditions to vary periodically in a 26- to 28-day cycle?
ALong term oscillations in the upper atmosphere
BCyclic variation in Earth’s radiation belts
CRotation of the Sun’s surface layers around its axis
DThe position of the Moon in its orbit
Answer: D
How long does it take a coronal mass ejection to affect radio propagation on Earth?
A28 days
B14 days
C4 to 8 minutes
D15 hours to several days
Answer: B
What does the K-index measure?
AThe relative position of sunspots on the surface of the Sun
BThe short-term stability of Earth’s geomagnetic field
CThe short-term stability of the Sun’s magnetic field
DThe solar radio flux at Boulder, Colorado
Answer: C
What does the A-index measure?
AThe relative position of sunspots on the surface of the Sun
BThe amount of polarization of the Sun’s electric field
CThe long-term stability of Earth’s geomagnetic field
DThe solar radio flux at Boulder, Colorado
Answer: B
How is long distance radio communication usually affected by the charged particles that reach Earth from solar coronal holes?
AHF communication is improved
BHF communication is disturbed
CVHF/UHF ducting is improved
DVHF/UHF ducting is disturbed
Answer: D
What factors affect the MUF?
APath distance and location
BTime of day and season
CSolar radiation and ionospheric disturbances
DAll these choices are correct
Answer: A
Which frequency will have the least attenuation for long-distance skip propagation?
AJust below the MUF
BJust above the LUF
CJust below the critical frequency
DJust above the critical frequency
Answer: A
Which of the following is a way to determine current propagation on a desired band from your station?
AUse a network of automated receiving stations on the internet to see where your transmissions are being received
BCheck the A-index
CSend a series of dots and listen for echoes
DAll these choices are correct
Answer: A
How does the ionosphere affect radio waves with frequencies below the MUF and above the LUF?
AThey are refracted back to Earth
BThey pass through the ionosphere
CThey are amplified by interaction with the ionosphere
DThey are refracted and trapped in the ionosphere to circle Earth
Answer: C
What usually happens to radio waves with frequencies below the LUF?
AThey are refracted back to Earth
BThey pass through the ionosphere
CThey are attenuated before reaching the destination
DThey are refracted and trapped in the ionosphere to circle Earth
Answer: A
What does LUF stand for?
AThe Lowest Usable Frequency for communications between two specific points
BThe Lowest Usable Frequency for communications to any point outside a 100-mile radius
CThe Lowest Usable Frequency during a 24-hour period
DThe Lowest Usable Frequency during the past 60 minutes
Answer: B
What does MUF stand for?
AThe Minimum Usable Frequency for communications between two points
BThe Maximum Usable Frequency for communications between two points
CThe Minimum Usable Frequency during a 24-hour period
DThe Maximum Usable Frequency during a 24-hour period
Answer: C
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the F2 region?
A180 miles
B1,200 miles
C2,500 miles
D12,000 miles
Answer: B
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the E region?
A180 miles
B1,200 miles
C2,500 miles
D12,000 miles
Answer: A
What happens to HF propagation when the LUF exceeds the MUF?
APropagation via ordinary skywave communications is not possible over that path
BHF communications over the path are enhanced
CDouble-hop propagation along the path is more common
DPropagation over the path on all HF frequencies is enhanced
Answer: D
Which of the following is typical of the lower HF frequencies during the summer?
APoor propagation at any time of day
BWorld-wide propagation during daylight hours
CHeavy distortion on signals due to photon absorption
DHigh levels of atmospheric noise or static
Answer: A
What is meant by the term “critical frequency” at a given incidence angle?
AThe highest frequency which is refracted back to Earth
BThe lowest frequency which is refracted back to Earth
CThe frequency at which the signal-to-noise ratio approaches unity
DThe frequency at which the signal-to-noise ratio is 6 dB
Answer: C
Why is skip propagation via the F2 region longer than that via the other ionospheric regions?
ABecause it is the densest
BBecause of the Doppler effect
CBecause it is the highest
DBecause of temperature inversions
Answer: D
What does the term “critical angle” mean, as applied to radio wave propagation?
AThe long path azimuth of a distant station
BThe short path azimuth of a distant station
CThe lowest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions
DThe highest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions
Answer: C
Why is long-distance communication on the 40-, 60-, 80-, and 160-meter bands more difficult during the day?
AThe F region absorbs signals at these frequencies during daylight hours
BThe F region is unstable during daylight hours
CThe D region absorbs signals at these frequencies during daylight hours
DThe E region is unstable during daylight hours
Answer: B
What is a characteristic of HF scatter?
APhone signals have high intelligibility
BSignals have a fluttering sound
CThere are very large, sudden swings in signal strength
DScatter propagation occurs only at night
Answer: D
What makes HF scatter signals often sound distorted?
AThe ionospheric region involved is unstable
BGround waves are absorbing much of the signal
CThe E region is not present
DEnergy is scattered into the skip zone through several different paths
Answer: A
Why are HF scatter signals in the skip zone usually weak?
AOnly a small part of the signal energy is scattered into the skip zone
BSignals are scattered from the magnetosphere, which is not a good reflector
CPropagation is via ground waves, which absorb most of the signal energy
DPropagation is via ducts in the F region, which absorb most of the energy
Answer: B
What type of propagation allows signals to be heard in the transmitting station’s skip zone?
AFaraday rotation
BScatter
CChordal hop
DShort-path
Answer: B
What is near vertical incidence skywave (NVIS) propagation?
APropagation near the MUF
BShort distance MF or HF propagation at high elevation angles
CLong path HF propagation at sunrise and sunset
DDouble hop propagation near the LUF
Answer: D
Which ionospheric region is the most absorbent of signals below 10 MHz during daylight hours?
AThe F2 region
BThe F1 region
CThe E region
DThe D region