🔍 Key Concepts

• MF-HF GMDSS antennas are usually long wire or whip antennas matched by an antenna tuner/ATU located close to the feed point • Correct antenna length is related to the wavelength (λ) of the frequencies used, often some fraction like quarter-wave for efficient radiation • MF-HF GMDSS equipment manuals specify minimum and recommended antenna lengths for safe and effective operation

💭 Think About

• What is the approximate wavelength of MF frequencies (around 2–3 MHz) and HF frequencies (say 8–12 MHz), and would a 10 ft antenna be a reasonable fraction of that wavelength? • Why is it important that the MF-HF antenna be a long vertical or long-wire radiator, and how does that compare to a short dipole or a VHF antenna? • Which option most closely matches what a typical MF-HF GMDSS installation manual would recommend for an emergency/temporary wire antenna when the whip is lost?

✅ Before You Answer

• Compare each proposed antenna length against a realistic fraction of the wavelength for MF-HF (is 10 ft long or 35–40 ft closer to what’s normally used?). • Check whether connecting MF/HF gear to a VHF antenna makes technical sense, given VHF operates near 156 MHz (very short wavelength) vs. MF-HF (much longer wavelength). • Confirm which option mentions following the equipment instruction manual, which is a key principle in GMDSS equipment setup and repair.