Decasignal for skywave propagation corresponds to which frequency range?

Decasignal for skywave propagation corresponds to which frequency range?

• A. 3 MHz - 30 MHz
• B. 3 Hz - 30 Hz
• C. 30 MHz - 300 MHz
• D. 300 kHz - 3 MHz

Answer: (A)

Skywave propagation relies on the ionosphere reflecting radio waves back to Earth, which happens best in the high-frequency range. Signals in roughly 3 to 30 MHz can be refracted by the ionosphere and return to distant receivers, enabling long-distance communication. The decameter region, around a 10-meter wavelength, sits near 30 MHz, so it falls within this HF window. That’s why the range 3 to 30 MHz is the correct match for decameter skywave signals. Frequencies well below this (ELF/SLF) or well above this (VHF/UHF) don’t produce the same ionospheric reflection used for long-range propagation.

Skywave propagation relies on the ionosphere reflecting radio waves back to Earth, which happens best in the high-frequency range. Signals in roughly 3 to 30 MHz can be refracted by the ionosphere and return to distant receivers, enabling long-distance communication. The decameter region, around a 10-meter wavelength, sits near 30 MHz, so it falls within this HF window. That’s why the range 3 to 30 MHz is the correct match for decameter skywave signals. Frequencies well below this (ELF/SLF) or well above this (VHF/UHF) don’t produce the same ionospheric reflection used for long-range propagation.