E3 Radio Wave Propagation Flashcards
E3A01 (D)
What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by Moon bounce?
D. 12,000 miles, if the Moon is visible by both stations
E3A02 (B)
What characterizes libration fading of an EME signal?
B. A fluttery irregular fading
E3A03 (A)
When scheduling EME contacts, which of these conditions will generally result in the least path loss?
A. When the Moon is at perigee
E3A04 (D)
What do Hepburn maps predict?
D. Probability of tropospheric propagation
E3A05 (C)
Tropospheric propagation of microwave signals often occurs along what weather related structure?
C. Warm and cold fronts
E3A06 (C)
Which of the following is required for microwave propagation via rain scatter?
C. The rain must be within radio range of both stations
E3A07 (C)
Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
C. Bodies of water
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. The E layer
E3A09 (C)
Which of the following frequency range is most suited for meteor scatter communications?
C. 28 MHz - 148 MHz
E3A10 (B)
Which type of atmospheric structure can create a path for microwave propagation?
B. Temperature inversion
E3A11 (B)
What is a typical range for tropospheric propagation of microwave signals?
B. 100 miles to 300 miles
E3A12 (C)
What is the cause of auroral activity?
C. The interaction in the E layer of charged particles from the Sun with the Earth’s magnetic field
E3A13 (A)
Which emission mode is best for aurora propagation?
A. CW
E3A14 (B)
From the contiguous 48 states, in which approximate direction should an antenna be pointed to take maximum advantage of aurora propagation?
B. North
E3A15 (C)
What is an electromagnetic wave?
C. A wave consisting of an electric field and a magnetic field oscillating at right angles to each other
E3A16 (D)
Which of the following best describes electromagnetic waves traveling in free space?
D. Changing electric and magnetic fields propagate the energy
E3A17 (B)
What is meant by circularly polarized electromagnetic waves?
B. Waves with a rotating electric field
E3B01 (A)
What is transequatorial propagation?
A. Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
E3B02 (C)
What is the approximate maximum range for signals using transequatorial propagation?
C. 5000 miles
E3B03 (C)
What is the best time of day for transequatorial propagation?
C. Afternoon or early evening
E3B04 (B)
What is meant by the terms extraordinary and ordinary waves?
B. Independent waves created in the ionosphere that are elliptically polarized
E3B05 (C)
Which amateur bands typically support long-path propagation?
C. 160 meters to 10 meters
E3B06 (B)
Which of the following amateur bands most frequently provides long-path propagation?
B. 20 meters
E3B07 (D)
Which of the following could account for hearing an echo on the received signal of a distant station?
D. Receipt of a signal by more than one path
E3B08 (D)
What type of HF propagation is probably occurring if radio signals travel along the terminator between daylight and darkness?
D. Gray-line
E3B09 (A)
At what time of year is Sporadic E propagation most likely to occur?
A. Around the solstices, especially the summer solstice
E3B10 (B)
What is the cause of gray-line propagation?
B. At twilight and sunrise, D-layer absorption is low while E-layer and F-layer propagation remains high
E3B11 (D)
At what time of day is Sporadic-E propagation most likely to occur?
D. Any time
E3B12 (B)
What is the primary characteristic of chordal hop propagation?
B. Successive ionospheric reflections without an intermediate reflection from the ground
E3B13 (A)
Why is chordal hop propagation desirable?
A. The signal experiences less loss along the path compared to normal skip propagation
E3B14 (C)
What happens to linearly polarized radio waves that split into ordinary and extraordinary waves in the ionosphere?
C. They become elliptically polarized
E3C01 (B)
What does the term ray tracing describe in regard to radio communications?
B. Modeling a radio wave’s path through the ionosphere
E3C02 (A)
What is indicated by a rising A or K index?
A. Increasing disruption of the geomagnetic field
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?
B. Polar paths
E3C04 (C)
What does the value of Bz (B sub Z) represent?
C. Direction and strength of the interplanetary magnetic field
E3C05 (A)
What orientation of Bz (B sub z) increases the likelihood that incoming particles from the Sun will cause disturbed conditions?
A. Southward
E3C06 (A)
By how much does the VHF/UHF radio horizon distance exceed the geometric horizon?
A. By approximately 15 percent of the distance
E3C07 (D)
Which of the following descriptors indicates the greatest solar flare intensity?
D. Class X
E3C08 (A)
What does the space weather term G5 mean?
A. An extreme geomagnetic storm
E3C09 (C)
How does the intensity of an X3 flare compare to that of an X2 flare?
C. Twice as great
E3C10 (B)
What does the 304A solar parameter measure?
B. UV emissions at 304 angstroms, correlated to solar flux index
E3C11 (C)
What does VOACAP software model?
C. HF propagation
E3C12 (C)
How does the maximum distance of ground-wave propagation change when the signal frequency is increased?
C. It decreases
E3C13 (A)
What type of polarization is best for ground-wave propagation?
A. Vertical
E3C14 (D)
Why does the radio-path horizon distance exceed the geometric horizon?
D. Downward bending due to density variations in the atmosphere
E3C15 (B)
What might a sudden rise in radio background noise indicate?
B. A solar flare has occurred
