E3 Radio Wave Propagation

Question 1

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

Answer 1

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

Question 2

E3A02 (B)

What characterizes libration fading of an EME signal?

Answer 2

B. A fluttery irregular fading

Question 3

E3A03 (A)

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

Answer 3

A. When the Moon is at perigee

Question 4

E3A04 (D)

What do Hepburn maps predict?

Answer 4

D. Probability of tropospheric propagation

Question 5

E3A05 (C)

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

Answer 5

C. Warm and cold fronts

Question 6

E3A06 (C)

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

Answer 6

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

Question 7

E3A07 (C)

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

Answer 7

C. Bodies of water

Question 8

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

Answer 8

A. The E layer

Question 9

E3A09 (C)

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

Answer 9

C. 28 MHz - 148 MHz

Question 10

E3A10 (B)

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

Answer 10

B. Temperature inversion

Question 11

E3A11 (B)

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

Answer 11

B. 100 miles to 300 miles

Question 12

E3A12 (C)

What is the cause of auroral activity?

Answer 12

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

Question 13

E3A13 (A)

Which emission mode is best for aurora propagation?

Answer 13

A. CW

Question 14

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

Answer 14

B. North

Question 15

E3A15 (C)

What is an electromagnetic wave?

Answer 15

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

Question 16

E3A16 (D)

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

Answer 16

D. Changing electric and magnetic fields propagate the energy

Question 17

E3A17 (B)

What is meant by circularly polarized electromagnetic waves?

Answer 17

B. Waves with a rotating electric field

Question 18

E3B01 (A)

What is transequatorial propagation?

Answer 18

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

Question 19

E3B02 (C)

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

Answer 19

C. 5000 miles

Question 20

E3B03 (C)

What is the best time of day for transequatorial propagation?

Answer 20

C. Afternoon or early evening

Question 21

E3B04 (B)

What is meant by the terms extraordinary and ordinary waves?

Answer 21

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

Question 22

E3B05 (C)

Which amateur bands typically support long-path propagation?

Answer 22

C. 160 meters to 10 meters

Question 23

E3B06 (B)

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

Answer 23

B. 20 meters

Question 24

E3B07 (D)

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

Answer 24

D. Receipt of a signal by more than one path

Question 25

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

Answer 25

D. Gray-line

Question 26

E3B09 (A) | At what time of year is Sporadic E propagation most likely to occur?

Answer 26

A. Around the solstices, especially the summer solstice

Question 27

E3B10 (B) | What is the cause of gray-line propagation?

Answer 27

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

Question 28

E3B11 (D) | At what time of day is Sporadic-E propagation most likely to occur?

Answer 28

D. Any time

Question 29

E3B12 (B) | What is the primary characteristic of chordal hop propagation?

Answer 29

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

Question 30

E3B13 (A) | Why is chordal hop propagation desirable?

Answer 30

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

Question 31

E3B14 (C) | What happens to linearly polarized radio waves that split into ordinary and extraordinary waves in the ionosphere?

Answer 31

C. They become elliptically polarized

Question 32

E3C01 (B) | What does the term ray tracing describe in regard to radio communications?

Answer 32

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

Question 33

E3C02 (A) | What is indicated by a rising A or K index?

Answer 33

A. Increasing disruption of the geomagnetic field

Question 34

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?

Answer 34

B. Polar paths

Question 35

E3C04 (C) | What does the value of Bz (B sub Z) represent?

Answer 35

C. Direction and strength of the interplanetary magnetic field

Question 36

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

Answer 36

A. Southward

Question 37

E3C06 (A) | By how much does the VHF/UHF radio horizon distance exceed the geometric horizon?

Answer 37

A. By approximately 15 percent of the distance

Question 38

E3C07 (D) | Which of the following descriptors indicates the greatest solar flare intensity?

Answer 38

D. Class X

Question 39

E3C08 (A) | What does the space weather term G5 mean?

Answer 39

A. An extreme geomagnetic storm

Question 40

E3C09 (C) | How does the intensity of an X3 flare compare to that of an X2 flare?

Answer 40

C. Twice as great

Question 41

E3C10 (B) | What does the 304A solar parameter measure?

Answer 41

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

Question 42

E3C11 (C) | What does VOACAP software model?

Answer 42

C. HF propagation

Question 43

E3C12 (C) | How does the maximum distance of ground-wave propagation change when the signal frequency is increased?

Answer 43

C. It decreases

Question 44

E3C13 (A) | What type of polarization is best for ground-wave propagation?

Answer 44

A. Vertical

Question 45

E3C14 (D) | Why does the radio-path horizon distance exceed the geometric horizon?

Answer 45

D. Downward bending due to density variations in the atmosphere

Question 46

E3C15 (B) | What might a sudden rise in radio background noise indicate?

Answer 46

B. A solar flare has occurred