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E3A08

RADIO WAVE PROPAGATION · 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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When a meteor strikes the Earth's atmosphere, a linear ionized region is formed at what region of the ionosphere?

  1. AThe E region
  2. BThe F1 region
  3. CThe F2 region
  4. DThe D region
Why Meteors burn up and ionize the air at roughly 85 to 120 km altitude, which is exactly the height of the E region. The friction of the meteoroid leaves a dense, cylindrical (linear) column of ionization along its path that can refract or reflect VHF signals for a fraction of a second up to a few seconds. That is why meteor scatter contacts on 6 meters and 2 meters behave like brief, intense sporadic-E style openings out to about 1200 miles.
Watch out The F1 and F2 regions sit much higher, around 150 to 400 km, well above where meteors ablate, and the D region (50 to 90 km) is the absorbing layer that mainly attenuates lower HF by day rather than forming meteor trails.
Meteor trails burn up around 100 km, the same height as sporadic E. Meteors = E region.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
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The rest of E3A

  1. E3A01 What is the approximate maximum separation measured along the surface of the Earth between two stations commu…
  2. E3A02 What characterizes libration fading of an EME signal?
  3. E3A03 When scheduling EME contacts, which of these conditions will generally result in the least path loss?
  4. E3A04 In what direction does an electromagnetic wave travel?
  5. E3A05 How are the component fields of an electromagnetic wave oriented?
  6. E3A06 What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?
  7. E3A07 Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
  8. E3A08 When a meteor strikes the Earth's atmosphere, a linear ionized region is formed at what region of the ionosph…
  9. E3A09 Which of the following frequency ranges is most suited for meteor-scatter communications?
  10. E3A10 What determines the speed of electromagnetic waves through a medium?
  11. E3A11 What is a typical range for tropospheric duct propagation of microwave signals?
  12. E3A12 What is most likely to result in auroral propagation?
  13. E3A13 Which of these emission modes is best for auroral propagation?
  14. E3A14 What are circularly polarized electromagnetic waves?
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