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logseq/bak/pages/E3A/2025-05-01T20_36_29.890Z.Desktop.md
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E3A Electromagnetic Waves and Specialized Propagation: Earth-Moon-Earth (EME) communications; meteor scatter; microwave tropospheric and scatter propagation; auroral propagation; daily variation of ionospheric propagation; circular polarization
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- [[E3A01]] (D)
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What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?
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- [[A.]] 2,000 miles, if the moon is at perigee
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- [[B.]] 2,000 miles, if the moon is at apogee
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- [[C.]] 5,000 miles, if the moon is at perigee
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- [[D.]] 12,000 miles, if the moon is “visible” by both stations
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--
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- [[E3A02]] (B)
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What characterizes libration fading of an EME signal?
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- [[A.]] A slow change in the pitch of the CW signal
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- [[B.]] A fluttery, irregular fading
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- [[C.]] A gradual loss of signal as the sun rises
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- [[D.]] The returning echo is several hertz lower in frequency than the transmitted signal
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--
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- [[E3A03]] (A)
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When scheduling EME contacts, which of these conditions will generally result in the least path loss?
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- [[A.]] When the Moon is at perigee
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- [[B.]] When the Moon is full
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- [[C.]] When the Moon is at apogee
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- [[D.]] When the MUF is above 30 MHz
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--
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- [[E3A04]] (D)
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In what direction does an electromagnetic wave travel?
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- [[A.]] It depends on the phase angle of the magnetic field
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- [[B.]] It travels parallel to the electric and magnetic fields
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- [[C.]] It depends on the phase angle of the electric field
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- [[D.]] It travels at a right angle to the electric and magnetic fields
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--
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- [[E3A05]] (C)
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How are the component fields of an electromagnetic wave oriented?
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- [[A.]] They are parallel
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- [[B.]] They are tangential
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- [[C.]] They are at right angles
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- [[D.]] They are 90 degrees out of phase
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--
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- [[E3A06]] (B)
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What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?
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- [[A.]] Switch to a higher frequency HF band
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- [[B.]] Switch to a lower frequency HF band
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- [[C.]] Change to an antenna with a higher takeoff angle
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- [[D.]] Change to an antenna with greater beam width
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--
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- [[E3A07]] (C)
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Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
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- [[A.]] Mountain ranges
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- [[B.]] Stratocumulus clouds
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- [[C.]] Large bodies of water
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- [[D.]] Nimbus clouds
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--
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- [[E3A08]] (A)
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When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?
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- [[A.]] The E region
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- [[B.]] The F1 region
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- [[C.]] The F2 region
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- [[D.]] The D region
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--
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- [[E3A09]] (C)
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Which of the following frequency ranges is most suited for meteor-scatter communications?
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- [[A.]] 1.8 MHz - 1.9 MHz
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- [[B.]] 10 MHz - 14 MHz
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- [[C.]] 28 MHz - 148 MHz
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- [[D.]] 220 MHz - 450 MHz
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--
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- [[E3A10]] (D)
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What determines the speed of electromagnetic waves through a medium?
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- [[A.]] Resistance and reactance
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- [[B.]] Evanescence
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- [[C.]] Birefringence
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- [[D.]] The index of refraction
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--
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- [[E3A11]] (B)
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What is a typical range for tropospheric duct propagation of microwave signals?
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- [[A.]] 10 miles to 50 miles
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- [[B.]] 100 miles to 300 miles
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- [[C.]] 1,200 miles
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- [[D.]] 2,500 miles
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--
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- [[E3A12]] (C)
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What is most likely to result in auroral propagation?
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- [[A.]] Meteor showers
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- [[B.]] Quiet geomagnetic conditions
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- [[C.]] Severe geomagnetic storms
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- [[D.]] Extreme low-pressure areas in polar regions
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--
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- [[E3A13]] (A)
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Which of these emission modes is best for auroral propagation?
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- [[A.]] CW
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- [[B.]] SSB
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- [[C.]] FM
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- [[D.]] RTTY
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--
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- [[E3A14]] (B)
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What are circularly polarized electromagnetic waves?
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- [[A.]] Waves with an electric field bent into a circular shape
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- [[B.]] Waves with rotating electric and magnetic fields
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- [[C.]] Waves that circle Earth
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- [[D.]] Waves produced by a loop antenna
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99
logseq/bak/pages/E3A/2025-05-01T20_36_51.616Z.Desktop.md
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99
logseq/bak/pages/E3A/2025-05-01T20_36_51.616Z.Desktop.md
Normal file
@ -0,0 +1,99 @@
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E3A Electromagnetic Waves and Specialized Propagation: Earth-Moon-Earth (EME) communications; meteor scatter; microwave tropospheric and scatter propagation; auroral propagation; daily variation of ionospheric propagation; circular polarization
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|
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- [[E3A01]] (D)
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What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME? #card
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- [[A.]] 2,000 miles, if the moon is at perigee
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- [[B.]] 2,000 miles, if the moon is at apogee
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- [[C.]] 5,000 miles, if the moon is at perigee
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- [[D.]] 12,000 miles, if the moon is “visible” by both stations
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--
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- [[E3A02]] (B)
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What characterizes libration fading of an EME signal? #card
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- [[A.]] A slow change in the pitch of the CW signal
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- [[B.]] A fluttery, irregular fading
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- [[C.]] A gradual loss of signal as the sun rises
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- [[D.]] The returning echo is several hertz lower in frequency than the transmitted signal
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--
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- [[E3A03]] (A)
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When scheduling EME contacts, which of these conditions will generally result in the least path loss? #card
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- [[A.]] When the Moon is at perigee
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- [[B.]] When the Moon is full
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- [[C.]] When the Moon is at apogee
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- [[D.]] When the MUF is above 30 MHz
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--
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- [[E3A04]] (D)
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In what direction does an electromagnetic wave travel? #card
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- [[A.]] It depends on the phase angle of the magnetic field
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- [[B.]] It travels parallel to the electric and magnetic fields
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- [[C.]] It depends on the phase angle of the electric field
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- [[D.]] It travels at a right angle to the electric and magnetic fields
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--
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- [[E3A05]] (C)
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How are the component fields of an electromagnetic wave oriented? #card
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- [[A.]] They are parallel
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- [[B.]] They are tangential
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- [[C.]] They are at right angles
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- [[D.]] They are 90 degrees out of phase
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--
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- [[E3A06]] (B)
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What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness? #card
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- [[A.]] Switch to a higher frequency HF band
|
||||
- [[B.]] Switch to a lower frequency HF band
|
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- [[C.]] Change to an antenna with a higher takeoff angle
|
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- [[D.]] Change to an antenna with greater beam width
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--
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- [[E3A07]] (C)
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Atmospheric ducts capable of propagating microwave signals often form over what geographic feature? #card
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- [[A.]] Mountain ranges
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- [[B.]] Stratocumulus clouds
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- [[C.]] Large bodies of water
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- [[D.]] Nimbus clouds
|
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--
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- [[E3A08]] (A)
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When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere? #card
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- [[A.]] The E region
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- [[B.]] The F1 region
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- [[C.]] The F2 region
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- [[D.]] The D region
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--
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- [[E3A09]] (C)
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Which of the following frequency ranges is most suited for meteor-scatter communications? #card
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- [[A.]] 1.8 MHz - 1.9 MHz
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- [[B.]] 10 MHz - 14 MHz
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- [[C.]] 28 MHz - 148 MHz
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- [[D.]] 220 MHz - 450 MHz
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--
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- [[E3A10]] (D)
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What determines the speed of electromagnetic waves through a medium? #card
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- [[A.]] Resistance and reactance
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- [[B.]] Evanescence
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- [[C.]] Birefringence
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- [[D.]] The index of refraction
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--
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- [[E3A11]] (B)
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What is a typical range for tropospheric duct propagation of microwave signals? #card
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- [[A.]] 10 miles to 50 miles
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- [[B.]] 100 miles to 300 miles
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- [[C.]] 1,200 miles
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- [[D.]] 2,500 miles
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--
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- [[E3A12]] (C)
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What is most likely to result in auroral propagation? #card
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- [[A.]] Meteor showers
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- [[B.]] Quiet geomagnetic conditions
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- [[C.]] Severe geomagnetic storms
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- [[D.]] Extreme low-pressure areas in polar regions
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--
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- [[E3A13]] (A)
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Which of these emission modes is best for auroral propagation? #card
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- [[A.]] CW
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- [[B.]] SSB
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- [[C.]] FM
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- [[D.]] RTTY
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--
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- [[E3A14]] (B)
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What are circularly polarized electromagnetic waves? #card
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- [[A.]] Waves with an electric field bent into a circular shape
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- [[B.]] Waves with rotating electric and magnetic fields
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- [[C.]] Waves that circle Earth
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- [[D.]] Waves produced by a loop antenna
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