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Amateur Radio License USA - General Class (2023 - 2027)

- Kapitel: RADIO WAVE PROPAGATION

- Unterkapitel: Ionospheric regions; critical angle and frequency; HF scatter; near vertical incidence skywave (NVIS)

?  Frage Nr. 145 / G3C02
What is meant by the term “critical frequency” at a given incidence angle?

!  Antwort
The lowest frequency which is refracted back to Earth
The highest frequency which is refracted back to Earth
The frequency at which the signal-to-noise ratio is 6 dB
The frequency at which the signal-to-noise ratio approaches unity
? Ergebnis