Propagation

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How does a higher sunspot number affect HF propagation?

What is a characteristic of HF communication compared with communications on VHF and higher frequencies?

What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?

What is the cause of short-term radio blackouts?

What is the solar flux index?

What causes tropospheric ducting?

What is generally the best time for long-distance 10 meter band propagation via the F region?

Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?

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

What are “extraordinary” and “ordinary” waves?

What is the effect of chordal-hop propagation?

At what time of day is sporadic-E propagation most likely to occur?

Which of the following are the least reliable bands for long-distance communications during periods of low solar activity?

What causes HF propagation conditions to vary periodically in a 26- to 28-day cycle?

What does the K-index measure?

What does the A-index measure?

What factors affect the MUF?

Which frequency will have the least attenuation for long-distance skip propagation?