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E3B10

RADIO WAVE PROPAGATION · Transequatorial propagation; long-path propagation; ordinary and extraordinary waves; chordal hop; sporadic-E mechanisms; ground-wave propagation

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What is the effect of chordal-hop propagation?

  1. AThe signal experiences less loss compared to multi-hop propagation, which uses Earth as a reflector
  2. BThe MUF for chordal-hop propagation is much lower than for normal skip propagation
  3. CAtmospheric noise is reduced in the direction of chordal-hop propagation
  4. DSignals travel faster along ionospheric chords
Why In normal multi-hop skip, the wave comes back to Earth between hops and the ground or sea reflection throws away a big chunk of the signal, plus the wave passes through the absorbing D region twice per hop. In chordal hop the signal skips along between ionospheric tilts, refracting from one region to the next without ever touching the ground, so those reflection and extra absorption losses are avoided. The result is unusually strong, low-loss signals over very long paths, which is why transequatorial and long-path openings can sound so good.
Watch out The idea that the MUF is lower is backwards: chordal paths often support higher usable frequencies, and nothing about this mode changes the speed of radio waves or atmospheric noise levels.
Chordal hop = the ionosphere passes the signal along without letting it touch the lossy ground.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
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The rest of E3B

  1. E3B01 Where is transequatorial propagation (TEP) most likely to occur?
  2. E3B02 What is the approximate maximum range for signals using transequatorial propagation?
  3. E3B03 At what time of day is transequatorial propagation most likely to occur?
  4. E3B04 What are "extraordinary" and "ordinary" waves?
  5. E3B05 Which of the following paths is most likely to support long-distance propagation on 160 meters?
  6. E3B06 On which of the following amateur bands is long-path propagation most frequent?
  7. E3B07 What effect does lowering a signal's transmitted elevation angle have on ionospheric HF skip propagation?
  8. E3B08 How does the maximum range of ground-wave propagation change when the signal frequency is increased?
  9. E3B09 At what time of year is sporadic-E propagation most likely to occur?
  10. E3B10 What is the effect of chordal-hop propagation?
  11. E3B11 At what time of day is sporadic-E propagation most likely to occur?
  12. E3B12 What is chordal-hop propagation?
  13. E3B13 What type of polarization is supported by ground-wave propagation?
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