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Ham Extra 2016-2020 > E3 Radio Wave Propagation > Flashcards

E3 Radio Wave Propagation Flashcards

1
Q

E3A01 (D)
What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by Moon bounce?

A

D. 12,000 miles, if the Moon is visible by both stations

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2
Q

E3A02 (B)

What characterizes libration fading of an EME signal?

A

B. A fluttery irregular fading

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3
Q

E3A03 (A)

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

A

A. When the Moon is at perigee

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4
Q

E3A04 (D)

What do Hepburn maps predict?

A

D. Probability of tropospheric propagation

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5
Q

E3A05 (C)

Tropospheric propagation of microwave signals often occurs along what weather related structure?

A

C. Warm and cold fronts

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6
Q

E3A06 (C)

Which of the following is required for microwave propagation via rain scatter?

A

C. The rain must be within radio range of both stations

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7
Q

E3A07 (C)

Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

A

C. Bodies of water

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8
Q

E3A08 (A)
When a meteor strikes the Earth’s atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?

A

A. The E layer

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9
Q

E3A09 (C)

Which of the following frequency range is most suited for meteor scatter communications?

A

C. 28 MHz - 148 MHz

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10
Q

E3A10 (B)

Which type of atmospheric structure can create a path for microwave propagation?

A

B. Temperature inversion

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11
Q

E3A11 (B)

What is a typical range for tropospheric propagation of microwave signals?

A

B. 100 miles to 300 miles

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12
Q

E3A12 (C)

What is the cause of auroral activity?

A

C. The interaction in the E layer of charged particles from the Sun with the Earth’s magnetic field

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13
Q

E3A13 (A)

Which emission mode is best for aurora propagation?

A

A. CW

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14
Q

E3A14 (B)
From the contiguous 48 states, in which approximate direction should an antenna be pointed to take maximum advantage of aurora propagation?

A

B. North

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15
Q

E3A15 (C)

What is an electromagnetic wave?

A

C. A wave consisting of an electric field and a magnetic field oscillating at right angles to each other

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16
Q

E3A16 (D)

Which of the following best describes electromagnetic waves traveling in free space?

A

D. Changing electric and magnetic fields propagate the energy

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17
Q

E3A17 (B)

What is meant by circularly polarized electromagnetic waves?

A

B. Waves with a rotating electric field

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18
Q

E3B01 (A)

What is transequatorial propagation?

A

A. Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator

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19
Q

E3B02 (C)

What is the approximate maximum range for signals using transequatorial propagation?

A

C. 5000 miles

20
Q

E3B03 (C)

What is the best time of day for transequatorial propagation?

A

C. Afternoon or early evening

21
Q

E3B04 (B)

What is meant by the terms extraordinary and ordinary waves?

A

B. Independent waves created in the ionosphere that are elliptically polarized

22
Q

E3B05 (C)

Which amateur bands typically support long-path propagation?

A

C. 160 meters to 10 meters

23
Q

E3B06 (B)

Which of the following amateur bands most frequently provides long-path propagation?

A

B. 20 meters

24
Q

E3B07 (D)

Which of the following could account for hearing an echo on the received signal of a distant station?

A

D. Receipt of a signal by more than one path

25
Q

E3B08 (D)
What type of HF propagation is probably occurring if radio signals travel along the terminator between daylight and darkness?

A

D. Gray-line

26
Q

E3B09 (A)

At what time of year is Sporadic E propagation most likely to occur?

A

A. Around the solstices, especially the summer solstice

27
Q

E3B10 (B)

What is the cause of gray-line propagation?

A

B. At twilight and sunrise, D-layer absorption is low while E-layer and F-layer propagation remains high

28
Q

E3B11 (D)

At what time of day is Sporadic-E propagation most likely to occur?

A

D. Any time

29
Q

E3B12 (B)

What is the primary characteristic of chordal hop propagation?

A

B. Successive ionospheric reflections without an intermediate reflection from the ground

30
Q

E3B13 (A)

Why is chordal hop propagation desirable?

A

A. The signal experiences less loss along the path compared to normal skip propagation

31
Q

E3B14 (C)

What happens to linearly polarized radio waves that split into ordinary and extraordinary waves in the ionosphere?

A

C. They become elliptically polarized

32
Q

E3C01 (B)

What does the term ray tracing describe in regard to radio communications?

A

B. Modeling a radio wave’s path through the ionosphere

33
Q

E3C02 (A)

What is indicated by a rising A or K index?

A

A. Increasing disruption of the geomagnetic field

34
Q

E3C03 (B)
Which of the following signal paths is most likely to experience high levels of absorption when the A index or K index is elevated?

A

B. Polar paths

35
Q

E3C04 (C)

What does the value of Bz (B sub Z) represent?

A

C. Direction and strength of the interplanetary magnetic field

36
Q

E3C05 (A)
What orientation of Bz (B sub z) increases the likelihood that incoming particles from the Sun will cause disturbed conditions?

A

A. Southward

37
Q

E3C06 (A)

By how much does the VHF/UHF radio horizon distance exceed the geometric horizon?

A

A. By approximately 15 percent of the distance

38
Q

E3C07 (D)

Which of the following descriptors indicates the greatest solar flare intensity?

A

D. Class X

39
Q

E3C08 (A)

What does the space weather term G5 mean?

A

A. An extreme geomagnetic storm

40
Q

E3C09 (C)

How does the intensity of an X3 flare compare to that of an X2 flare?

A

C. Twice as great

41
Q

E3C10 (B)

What does the 304A solar parameter measure?

A

B. UV emissions at 304 angstroms, correlated to solar flux index

42
Q

E3C11 (C)

What does VOACAP software model?

A

C. HF propagation

43
Q

E3C12 (C)

How does the maximum distance of ground-wave propagation change when the signal frequency is increased?

A

C. It decreases

44
Q

E3C13 (A)

What type of polarization is best for ground-wave propagation?

A

A. Vertical

45
Q

E3C14 (D)

Why does the radio-path horizon distance exceed the geometric horizon?

A

D. Downward bending due to density variations in the atmosphere

46
Q

E3C15 (B)

What might a sudden rise in radio background noise indicate?

A

B. A solar flare has occurred

Ham Extra 2016-2020 (10 decks)

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