All 39 Ham Radio Amateur Extra questions for E3 Radio Wave Propagation with the correct answers marked, from the official 2024-2028 question pool. Test yourself with the free practice exam.
E3A01
What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?
A. 2,000 miles, if the moon is at perigee
B. 2,000 miles, if the moon is at apogee
C. 5,000 miles, if the moon is at perigee
D. 12,000 miles, if the moon is “visible” by both stations ✓
E3A02
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
E3A03
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
E3A04
In what direction does an electromagnetic wave travel?
A. It depends on the phase angle of the magnetic field
B. It travels parallel to the electric and magnetic fields
C. It depends on the phase angle of the electric field
D. It travels at a right angle to the electric and magnetic fields ✓
E3A05
How are the component fields of an electromagnetic wave oriented?
A. They are parallel
B. They are tangential
C. They are at right angles ✓
D. They are 90 degrees out of phase
E3A06
What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?
A. Switch to a higher frequency HF band
B. Switch to a lower frequency HF band ✓
C. Change to an antenna with a higher takeoff angle
D. Change to an antenna with greater beam width
E3A07
Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
A. Mountain ranges
B. Stratocumulus clouds
C. Large bodies of water ✓
D. Nimbus clouds
E3A08
When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?
A. The E region ✓
B. The F1 region
C. The F2 region
D. The D region
E3A09
Which of the following frequency ranges 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
E3A10
What determines the speed of electromagnetic waves through a medium?
A. Resistance and reactance
B. Evanescence
C. Birefringence
D. The index of refraction ✓
E3A11
What is a typical range for tropospheric duct propagation of microwave signals?
A. 10 miles to 50 miles
B. 100 miles to 300 miles ✓
C. 1,200 miles
D. 2,500 miles
E3A12
What is most likely to result in auroral propagation?
A. Meteor showers
B. Quiet geomagnetic conditions
C. Severe geomagnetic storms ✓
D. Extreme low-pressure areas in polar regions
E3A13
Which of these emission modes is best for auroral propagation?
A. CW ✓
B. SSB
C. FM
D. RTTY
E3A14
What are circularly polarized electromagnetic waves?
A. Waves with an electric field bent into a circular shape
B. Waves with rotating electric and magnetic fields ✓
C. Waves that circle Earth
D. Waves produced by a loop antenna
E3B01
Where is transequatorial propagation (TEP) most likely to occur?
A. Between points separated by 2,000 miles to 3,000 miles over a path perpendicular to the geomagnetic equator ✓
B. Between points located 1,500 miles to 2,000 miles apart on the geomagnetic equator
C. Between points located at each other’s antipode
D. Through the region where the terminator crosses the geographic equator
E3B02
What is the approximate maximum range for signals using transequatorial propagation?
A. 1,000 miles
B. 2,500 miles
C. 5,000 miles ✓
D. 7,500 miles
E3B03
At what time of day is transequatorial propagation most likely to occur?
A. Morning
B. Noon
C. Afternoon or early evening ✓
D. Late at night
E3B04
What are “extraordinary” and “ordinary” waves?
A. Extraordinary waves exhibit rare long-skip propagation, compared to ordinary waves, which travel shorter distances
B. Independently propagating, elliptically polarized waves created in the ionosphere ✓
C. Long-path and short-path waves
D. Refracted rays and reflected waves
E3B05
Which of the following paths is most likely to support long-distance propagation on 160 meters?
A. A path entirely in sunlight
B. Paths at high latitudes
C. A direct north-south path
D. A path entirely in darkness ✓
E3B06
On which of the following amateur bands is long-path propagation most frequent?
A. 160 meters and 80 meters
B. 40 meters and 20 meters ✓
C. 10 meters and 6 meters
D. 6 meters and 2 meters
E3B07
What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?
A. Faraday rotation becomes stronger
B. The MUF decreases
C. The distance covered by each hop increases ✓
D. The critical frequency increases
E3B08
How does the maximum range 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 8 MHz
E3B09
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
E3B10
What is the effect of chordal-hop propagation?
A. The signal experiences less loss compared to multi-hop propagation, which uses Earth as a reflector ✓
B. The MUF for chordal-hop propagation is much lower than for normal skip propagation
C. Atmospheric noise is reduced in the direction of chordal-hop propagation
D. Signals travel faster along ionospheric chords
E3B11
At what time of day is sporadic-E propagation most likely to occur?
A. Between midnight and sunrise
B. Between sunset and midnight
C. Between sunset and sunrise
D. Between sunrise and sunset ✓
E3B12
What is chordal-hop propagation?
A. Propagation away from the great circle bearing between stations
B. Successive ionospheric refractions without an intermediate reflection from the ground ✓
C. Propagation across the geomagnetic equator
D. Signals reflected back toward the transmitting station
E3B13
What type of polarization is supported by ground-wave propagation?
A. Vertical ✓
B. Horizontal
C. Circular
D. Elliptical
E3C01
What is the cause of short-term radio blackouts?
A. Coronal mass ejections
B. Sunspots on the solar equator
C. North-oriented interplanetary magnetic field
D. Solar flares ✓
E3C02
What is indicated by a rising A-index or K-index?
A. Increasing disturbance of the geomagnetic field ✓
B. Decreasing disturbance of the geomagnetic field
C. Higher levels of solar UV radiation
D. An increase in the critical frequency
E3C03
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
B. Through the auroral oval ✓
C. Sporadic-E
D. NVIS
E3C04
What does the value of Bz (B sub z) represent?
A. Geomagnetic field stability
B. Critical frequency for vertical transmissions
C. North-south strength of the interplanetary magnetic field ✓
D. Duration of long-delayed echoes
E3C05
What orientation of Bz (B sub z) increases the likelihood that charged particles from the Sun will cause disturbed conditions?
A. Southward ✓
B. Northward
C. Eastward
D. Westward
E3C06
How does the VHF/UHF radio horizon compare to the geographic horizon?
A. It is approximately 15 percent farther ✓
B. It is approximately 20 percent nearer
C. It is approximately 50 percent farther
D. They are approximately the same
E3C07
Which of the following indicates the greatest solar flare intensity?
A. Class A
B. Class Z
C. Class M
D. Class X ✓
E3C08
Which of the following is the space-weather term for an extreme geomagnetic storm?
A. B9
B. X5
C. M9
D. G5 ✓
E3C09
What type of data is reported by amateur radio propagation reporting networks?
A. Solar flux
B. Electric field intensity
C. Magnetic declination
D. Digital-mode and CW signals ✓
E3C10
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 the solar flux index ✓
C. The solar wind velocity at an angle of 304 degrees from the solar equator, correlated to geomagnetic storms
D. The solar emission at 304 GHz, correlated to X-ray flare levels
E3C11
What does VOACAP software model?
A. AC voltage and impedance
B. VHF radio propagation
C. HF propagation ✓
D. AC current and impedance
E3C12
Which of the following is indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?
A. A temperature inversion has occurred
B. A coronal mass ejection impact or a solar flare has occurred ✓
C. Transequatorial propagation on 6 meters is likely
D. Long-path propagation on the higher HF bands is likely