What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?
D12,000 miles, if the moon is “visible” by both stations
extra pool
Subelement E3 question review
All 39 official questions with the exact winning phrase marked.
What characterizes libration fading of an EME signal?
BA fluttery, irregular fading
When scheduling EME contacts, which of these conditions will generally result in the least path loss?
AWhen the Moon is at perigee
In what direction does an electromagnetic wave travel?
DIt travels at a right angle to the electric and magnetic fields
How are the component fields of an electromagnetic wave oriented?
CThey are at right angles
What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?
BSwitch to a lower frequency HF band
Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
CLarge bodies of water
When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?
AThe E region
Which of the following frequency ranges is most suited for meteor-scatter communications?
C28 MHz - 148 MHz
What determines the speed of electromagnetic waves through a medium?
DThe index of refraction
What is a typical range for tropospheric duct propagation of microwave signals?
B100 miles to 300 miles
What is most likely to result in auroral propagation?
CSevere geomagnetic storms
Which of these emission modes is best for auroral propagation?
ACW
What are circularly polarized electromagnetic waves?
BWaves with rotating electric and magnetic fields
Where is transequatorial propagation (TEP) most likely to occur?
ABetween points separated by 2,000 miles to 3,000 miles over a path perpendicular to the geomagnetic equator
What is the approximate maximum range for signals using transequatorial propagation?
C5,000 miles
At what time of day is transequatorial propagation most likely to occur?
CAfternoon or early evening
What are “extraordinary” and “ordinary” waves?
BIndependently propagating, elliptically polarized waves created in the ionosphere
Which of the following paths is most likely to support long-distance propagation on 160 meters?
DA path entirely in darkness
On which of the following amateur bands is long-path propagation most frequent?
B40 meters and 20 meters
What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?
CThe distance covered by each hop increases
How does the maximum range of ground-wave propagation change when the signal frequency is increased?
CIt decreases
At what time of year is sporadic-E propagation most likely to occur?
AAround the solstices, especially the summer solstice
What is the effect of chordal-hop propagation?
AThe signal experiences less loss compared to multi-hop propagation, which uses Earth as a reflector
At what time of day is sporadic-E propagation most likely to occur?
DBetween sunrise and sunset
What is chordal-hop propagation?
BSuccessive ionospheric refractions without an intermediate reflection from the ground
What type of polarization is supported by ground-wave propagation?
AVertical
What is the cause of short-term radio blackouts?
DSolar flares
What is indicated by a rising A-index or K-index?
AIncreasing disturbance of the geomagnetic field
Which of the following signal paths is most likely to experience high levels of absorption when the A-index or K-index is elevated?
BThrough the auroral oval
What does the value of Bz (B sub z) represent?
CNorth-south strength of the interplanetary magnetic field
What orientation of Bz (B sub z) increases the likelihood that charged particles from the Sun will cause disturbed conditions?
ASouthward
How does the VHF/UHF radio horizon compare to the geographic horizon?
AIt is approximately 15 percent farther
Which of the following indicates the greatest solar flare intensity?
DClass X
Which of the following is the space-weather term for an extreme geomagnetic storm?
DG5
What type of data is reported by amateur radio propagation reporting networks?
DDigital-mode and CW signals
What does the 304A solar parameter measure?
BUV emissions at 304 angstroms, correlated to the solar flux index
What does VOACAP software model?
CHF propagation
Which of the following is indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?
BA coronal mass ejection impact or a solar flare has occurred