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Ham General 2015-2019 > SUBELEMENT G3 - RADIO WAVE PROPAGATION > Flashcards

SUBELEMENT G3 - RADIO WAVE PROPAGATION Flashcards

1
Q

G3A01 (A)

What is the significance of the sunspot number with regard to HF propagation?

A

A. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies

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2
Q

G3A02 (B)

What effect does a Sudden Ionospheric Disturbance have on the daytime ionospheric propagation of HF radio waves?

A

B. It disrupts signals on lower frequencies more than those on higher frequencies

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3
Q

G3A03 (C)
Approximately how long does it take the increased ultraviolet and X-ray radiation from solar flares to affect radio propagation on the Earth?

A

C. 8 minutes

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4
Q

G3A04 (D)

Which of the following are least reliable for long distance communications during periods of low solar activity?

A

D. 15 meters, 12 meters and 10 meters

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5
Q

G3A05 (D)

What is the solar flux index?

A

D. A measure of solar radiation at 10.7 centimeters wavelength

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6
Q

G3A06 (D)

What is a geomagnetic storm?

A

D. A temporary disturbance in the Earth’s magnetosphere

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7
Q

G3A07 (D)

At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight hours?

A

D. At any point in the solar cycle

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8
Q

G3A08 (B)

Which of the following effects can a geomagnetic storm have on radio propagation?

A

B. Degraded high-latitude HF propagation

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9
Q

G3A09 (C)

What effect does a high sunspot number have on radio communications?

A

C. Long-distance communication in the upper HF and lower VHF range is enhanced

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10
Q

G3A10 (C)

What causes HF propagation conditions to vary periodically in a 28 day cycle?

A

C. The Sun’s rotation on its axis

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11
Q

G3A11 (D)

Approximately how long is the typical sunspot cycle?

A

D. 11 years

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12
Q

G3A12 (B)

What does the K-index indicate?

A

B. The short term stability of the Earth’s magnetic field

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13
Q

G3A13 (C)

What does the A-index indicate?

A

C. The long term stability of the Earth’s geomagnetic field

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14
Q

G3A14 (B)

How are radio communications usually affected by the charged particles that reach the Earth from solar coronal holes?

A

B. HF communications are disturbed

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15
Q

G3A15 (D)

How long does it take charged particles from coronal mass ejections to affect radio propagation on the Earth?

A

D. 20 to 40 hours

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16
Q

G3A16 (A)

What is a possible benefit to radio communications resulting from periods of high geomagnetic activity?

A

A. Auroras that can reflect VHF signals

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17
Q

G3B01 (D)

How might a sky-wave signal sound if it arrives at your receiver by both short path and long path propagation?

A

D. A well-defined echo might be heard

18
Q

G3B02 (A)

Which of the following is a good indicator of the possibility of sky-wave propagation on the 6-meter band?

A

A. Short skip sky-wave propagation on the 10-meter band

19
Q

G3B03 (A)

Which of the following applies when selecting a frequency for lowest attenuation when transmitting on HF?

A

A. Select a frequency just below the MUF

20
Q

G3B04 (A)
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

A. Listen for signals from an international beacon in the frequency range you plan to use

21
Q

G3B05 (A)
What usually happens to radio waves with frequencies below the MUF and above the LUF when they are sent into the ionosphere?

A

A. They are bent back to the Earth

22
Q

G3B06 (C)

What usually happens to radio waves with frequencies below the LUF?

A

C. They are completely absorbed by the ionosphere

23
Q

G3B07 (A)

What does LUF stand for?

A

A. The Lowest Usable Frequency for communications between two points

24
Q

G3B08 (B)

What does MUF stand for?

A

B. The Maximum Usable Frequency for communications between two points

25
Q

G3B09 (C)
What is the approximate maximum distance along the Earth’s surface that is normally covered in one hop using the F2 region?

A

C. 2,500 miles

26
Q

G3B10 (B)
What is the approximate maximum distance along the Earth’s surface that is normally covered in one hop using the E region?

A

B. 1,200 miles

27
Q

G3B11 (A)

What happens to HF propagation when the LUF exceeds the MUF?

A

A. No HF radio frequency will support ordinary sky-wave communications over the path

28
Q

G3B12 (D)

What factor or factors affect the MUF?

A

A. Path distance and location
B. Time of day and season
C. Solar radiation and ionospheric disturbances
D. All of these choices are correct

29
Q

G3C01 (A)

Which ionospheric layer is closest to the surface of the Earth?

A

A. The D layer

30
Q

G3C02 (A)

Where on the Earth do ionospheric layers reach their maximum height?

A

A. Where the Sun is overhead

31
Q

G3C03 (C)

Why is the F2 region mainly responsible for the longest distance radio wave propagation?

A

C. Because it is the highest ionospheric region

32
Q

G3C04 (D)

What does the term “critical angle” mean as used in radio wave propagation?

A

D. The highest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions

33
Q

G3C05 (C)
Why is long distance communication on the 40-meter, 60-meter, 80-meter and 160-meter bands more difficult during the day?

A

C. The D layer absorbs signals at these frequencies during daylight hours

34
Q

G3C06 (B)

What is a characteristic of HF scatter signals?

A

B. They have a wavering sound

35
Q

G3C07 (D)

What makes HF scatter signals often sound distorted?

A

D. Energy is scattered into the skip zone through several different radio wave paths

36
Q

G3C08 (A)

Why are HF scatter signals in the skip zone usually weak?

A

A. Only a small part of the signal energy is scattered into the skip zone

37
Q

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

B. Scatter

38
Q

G3C10 (D)
Which of the following might be an indication that signals heard on the HF bands are being received via scatter propagation?

A

D. The signal is heard on a frequency above the Maximum Usable Frequency

39
Q

G3C11 (B)

Which of the following antenna types will be most effective for skip communications on 40-meters during the day?

A

B. A horizontal dipole placed between 1/8 and 1/4 wavelength above the ground

40
Q

G3C12 (D)

Which ionospheric layer is the most absorbent of long skip signals during daylight hours on frequencies below 10 MHz?

A

D. The D layer

41
Q

G3C13 (B)

What is Near Vertical Incidence Sky-wave (NVIS) propagation?

A

B. Short distance MF or HF propagation using high elevation angles

Ham General 2015-2019 (10 decks)

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