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Question 134

What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?

  1. Switch to a higher frequency HF band
  2. Switch to a lower frequency HF bandBonne réponse
  3. Change to an antenna with a higher takeoff angle
  4. Change to an antenna with greater beam width

Explication

As the path goes into darkness the F-region electrons recombine, the electron density falls, and the maximum usable frequency drops below the band in use, so moving to a lower band puts the signal back under the MUF. Switching higher would leave the signal above the MUF and it would pass out through the ionosphere, and no antenna takeoff angle or beamwidth can restore refraction the ionosphere is no longer able to provide.

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Question 134: What should be done to continue a long-distance contact… · FCC Amateur Extra Class (Element 4) · Questena