US_EXTRA
Amateur Extra - Radio wave propagation
Radio wave propagation groups the E3 section questions for focused review and easier weak-point tracking.
39
Questions
9
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- Amateur Extra
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- Radio wave propagation
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Read the condition in the stem before comparing key terms in the options.
Study rules, calculations, and equipment questions as separate patterns.
After this topic, return to the full pool for mixed practice.
Topic Study Guide
This section covers advanced radio wave propagation phenomena, including Earth-Moon-Earth (EME), Transequatorial Propagation (TEP), meteor scatter, and the physics of electromagnetic waves. Mastering these concepts is crucial for Extra class long-distance communication.
High-Yield Checks
- EME Characteristics: Perigee offers the least path loss, maximum separation is 12,000 miles, and libration fading is fluttery and irregular.
- TEP (Transequatorial Propagation): Occurs perpendicular to the geomagnetic equator, peaks in the afternoon/early evening, with a maximum range of about 5,000 miles.
- Electromagnetic Wave Physics: Electric and magnetic fields are at right angles to each other and the direction of travel. Speed is determined by the index of refraction.
- Band-Specific Propagation: Meteor scatter happens in the E region (28-148 MHz); auroral scatter requires CW during severe geomagnetic storms; 160m DX requires a path entirely in darkness.
Trap Patterns
- Confusing 'perigee' and 'apogee' in EME questions. Perigee is the closest point to Earth, resulting in the least path loss.
- Assuming higher frequencies always travel further. Ground-wave propagation range actually decreases as frequency increases, and a dropping MUF requires switching to lower HF bands.
- Selecting voice modes for auroral propagation. Severe Doppler shift distorts SSB/FM; only CW remains readable.
- Misidentifying TEP geometry. It occurs perpendicular to the geomagnetic equator, not parallel to the geographic equator.
Review Steps
- Group questions by specific propagation modes (EME, TEP, Auroral, Meteor Scatter) and memorize their unique triggers and limits.
- Associate specific atmospheric layers and frequency ranges with their phenomena, such as the E region and 28-148 MHz for meteor scatter.
- Visualize the 3D orthogonal structure of electromagnetic waves to easily answer questions about field orientation and polarization.
- Contrast day and night effects across different bands, noting that 160m requires total darkness while a dropping MUF requires moving to lower frequencies.
Quick Checks
- What is the maximum separation for EME contacts, and which lunar position provides the least path loss?
- Which emission mode is required to maintain readability during auroral propagation?
- How are the electric and magnetic fields of an electromagnetic wave oriented?
- What happens to the maximum range of ground-wave propagation when the frequency is increased?
Questions in This Topic
Choose Practice ModeE3A01What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?E3A02What characterizes libration fading of an EME signal?E3A03When scheduling EME contacts, which of these conditions will generally result in the least path loss?E3A04In what direction does an electromagnetic wave travel?E3A05How are the component fields of an electromagnetic wave oriented?E3A06What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?E3A07Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?E3A08When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?E3A09Which of the following frequency ranges is most suited for meteor-scatter communications?E3A10What determines the speed of electromagnetic waves through a medium?E3A11What is a typical range for tropospheric duct propagation of microwave signals?E3A12What is most likely to result in auroral propagation?E3A13Which of these emission modes is best for auroral propagation?E3A14What are circularly polarized electromagnetic waves?E3B01Where is transequatorial propagation (TEP) most likely to occur?E3B02What is the approximate maximum range for signals using transequatorial propagation?E3B03At what time of day is transequatorial propagation most likely to occur?E3B04What are “extraordinary” and “ordinary” waves?E3B05Which of the following paths is most likely to support long-distance propagation on 160 meters?E3B06On which of the following amateur bands is long-path propagation most frequent?E3B07What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?E3B08How does the maximum range of ground-wave propagation change when the signal frequency is increased?E3B09At what time of year is sporadic-E propagation most likely to occur?E3B10What is the effect of chordal-hop propagation?E3B11At what time of day is sporadic-E propagation most likely to occur?E3B12What is chordal-hop propagation?E3B13What type of polarization is supported by ground-wave propagation?E3C01What is the cause of short-term radio blackouts?E3C02What is indicated by a rising A-index or K-index?E3C03Which of the following signal paths is most likely to experience high levels of absorption when the A-index or K-index is elevated?E3C04What does the value of Bz (B sub z) represent?E3C05What orientation of Bz (B sub z) increases the likelihood that charged particles from the Sun will cause disturbed conditions?E3C06How does the VHF/UHF radio horizon compare to the geographic horizon?E3C07Which of the following indicates the greatest solar flare intensity?E3C08Which of the following is the space-weather term for an extreme geomagnetic storm?E3C09What type of data is reported by amateur radio propagation reporting networks?E3C10What does the 304A solar parameter measure?E3C11What does VOACAP software model?E3C12Which of the following is indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?
More Topics
Extra class rules and station restrictionsOperating procedures and special operationsReceivers, transmitters, and measurementsElectrical principles and calculationsComponents and circuit devicesPractical circuits and system designSignals, modulation, and digital modesAntennas and transmission linesSafety