Amateur Extra Class Exam Question Pool- Subelement E-3

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SUBELEMENT E3 - RADIO WAVE PROPAGATION [3 Exam Questions - 3 Groups]



E3A -  Electromagnetic waves; Earth-Moon-Earth communications; meteor scatter; microwave tropospheric and scatter propagation; aurora propagation




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

A. 500 miles, if the Moon is at perigee

B. 2000 miles, if the Moon is at apogee

C. 5000 miles, if the Moon is at perigee

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




What characterizes libration fading of an EME signal?

A. A slow change in the pitch of the CW signal

B. A fluttery irregular fading

C. A gradual loss of signal as the Sun rises

D. The returning echo is several Hertz lower in frequency than the transmitted signal




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

A. When the Moon is at perigee

B. When the Moon is full

C. When the Moon is at apogee

D. When the MUF is above 30 MHz




What do Hepburn maps predict?

A. Sporadic E propagation

B. Locations of auroral reflecting zones

C. Likelihood of rain-scatter along cold or warm fronts

D. Probability of tropospheric propagation




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

A. Gray-line

B. Lightning discharges

C. Warm and cold fronts

D. Sprites and jets




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

A. Rain droplets must be electrically charged

B. Rain droplets must be within the E layer

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

D. All of these choices are correct




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

A. Mountain ranges

B. Forests

C. Bodies of water

D. Urban areas




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

B. The F1 layer

C. The F2 layer

D. The D layer




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

A. 1.8 MHz - 1.9 MHz

B. 10 MHz - 14 MHz

C. 28 MHz - 148 MHz

D. 220 MHz - 450 MHz




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

A. The jet stream

B. Temperature inversion

C. Wind shear

D. Dust devil




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

A. 10 miles to 50 miles

B. 100 miles to 300 miles

C. 1200 miles

D. 2500 miles




What is the cause of auroral activity?

A. The interaction in the F2 layer between the solar wind and the Van Allen belt

B. A low sunspot level combined with tropospheric ducting

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

D. Meteor showers concentrated in the extreme northern and southern latitudes




Which emission mode is best for aurora propagation?








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

A. South

B. North

C. East

D. West




What is an electromagnetic wave?

A. A wave of alternating current, in the core of an electromagnet

B. A wave consisting of two electric fields at parallel right angles to each other

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

D. A wave consisting of two magnetic fields at right angles to each other




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

A. Electric and magnetic fields become aligned as they travel

B. The energy propagates through a medium with a high refractive index

C. The waves are reflected by the ionosphere and return to their source

D. Changing electric and magnetic fields propagate the energy




What is meant by circularly polarized electromagnetic waves?

A. Waves with an electric field bent into a circular shape

B. Waves with a rotating electric field

C. Waves that circle the Earth

D. Waves produced by a loop antenna










E3B -  Transequatorial propagation; long path; gray-line; multi-path; ordinary and extraordinary waves; chordal hop, sporadic E mechanisms




What is transequatorial propagation?

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

B. Propagation between any two points located on the magnetic equator

C. Propagation between two continents by way of ducts along the magnetic equator

D. Propagation between two stations at the same latitude




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

A. 1000 miles

B. 2500 miles

C. 5000 miles

D. 7500 miles




What is the best time of day for transequatorial propagation?

A. Morning

B. Noon

C. Afternoon or early evening

D. Late at night




What is meant by the terms extraordinary and ordinary waves?

A. Extraordinary waves describe rare long skip propagation compared to ordinary waves which travel shorter distances

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

C. Long path and short path waves

D. Refracted rays and reflected waves




Which amateur bands typically support long-path propagation?

A. 160 meters to 40 meters

B. 30 meters to 10 meters

C. 160 meters to 10 meters

D. 6 meters to 2 meters




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

A. 80 meters

B. 20 meters

C. 10 meters

D. 6 meters




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

A. High D layer absorption

B. Meteor scatter

C. Transmit frequency is higher than the MUF

D. Receipt of a signal by more than one path




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

A. Transequatorial

B. Sporadic-E

C. Long-path

D. Gray-line




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

A. Around the solstices, especially the summer solstice

B. Around the solstices, especially the winter solstice

C. Around the equinoxes, especially the spring equinox

D. Around the equinoxes, especially the fall equinox




What is the cause of gray-line propagation?

A. At midday, the Sun super heats the ionosphere causing increased refraction of radio waves

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

C. In darkness, solar absorption drops greatly while atmospheric ionization remains steady

D. At mid-afternoon, the Sun heats the ionosphere decreasing radio wave refraction and the MUF




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

A. Around sunset

B. Around sunrise

C. Early evening

D. Any time




What is the primary characteristic of chordal hop propagation?

A. Propagation away from the great circle bearing between stations

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

C. Propagation across the geomagnetic equator

D. Signals reflected back toward the transmitting station




Why is chordal hop propagation desirable?

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

B. The MUF for chordal hop propagation is much lower than for normal skip propagation

C. Atmospheric noise is lower in the direction of chordal hop propagation

D. Signals travel faster along ionospheric chords




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

A. They are bent toward the magnetic poles

B. Their polarization is randomly modified

C. They become elliptically polarized

D. They become phase-locked









E3C -  Radio-path horizon; less common propagation modes; propagation prediction techniques and modeling; space weather parameters and amateur radio




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

A. The process in which an electronic display presents a pattern

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

C. Determining the radiation pattern from an array of antennas

D. Evaluating high voltage sources for X-Rays




What is indicated by a rising A or K index?

A. Increasing disruption of the geomagnetic field

B. Decreasing disruption of the geomagnetic field

C. Higher levels of solar UV radiation

D. An increase in the critical frequency




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. Transequatorial propagation

B. Polar paths

C. Sporadic-E





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

A. Geomagnetic field stability

B. Critical frequency for vertical transmissions

C. Direction and strength of the interplanetary magnetic field

D. Duration of long-delayed echoes




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

A. Southward

B. Northward

C. Eastward

D. Westward




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

A. By approximately 15 percent of the distance

B. By approximately twice the distance

C. By approximately 50 percent of the distance

D. By approximately four times the distance




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

A. Class A

B. Class B

C. Class M

D. Class X




What does the space weather term G5 mean?

A. An extreme geomagnetic storm

B. Very low solar activity

C. Moderate solar wind

D. Waning sunspot numbers




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

A. 10 percent greater

B. 50 percent greater

C. Twice as great

D. Four times as great




What does the 304A solar parameter measure?

A. The ratio of X-Ray flux to radio flux, correlated to sunspot number

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

C. The solar wind velocity at 304 degrees from the solar equator, correlated to solar activity

D. The solar emission at 304 GHz, correlated to X-Ray flare levels




What does VOACAP software model?

A. AC voltage and impedance

B. VHF radio propagation

C. HF propagation

D. AC current and impedance




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

A. It stays the same

B. It increases

C. It decreases

D. It peaks at roughly 14 MHz




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

A. Vertical

B. Horizontal

C. Circular

D. Elliptical




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

A. E-region skip

B. D-region skip

C. Downward bending due to aurora refraction

D. Downward bending due to density variations in the atmosphere




What might a sudden rise in radio background noise indicate?

A. A meteor ping

B. A solar flare has occurred

C. Increased transequatorial propagation likely

D. Long-path propagation is occurring


Subelement E-1           Subelement E-2          Subelement E-3          Subbelement E-4          Subelement E-5
Subelement E-6           Subelement E-7          Subelement E-8          Subbelement E-9          Subelement E-0