Question 22B5

A ship's MF-HF GMDSS system operates over a wide frequency range, typically from 2 MHz to 30 MHz. To regain operation with a replacement wire antenna, it needs sufficient physical length to allow the antenna tuner to efficiently match the transceiver to the antenna across these frequencies. Option C is correct because a wire antenna approximately 35-40 feet long provides a suitable compromise. This length is not overly short for the lower MF-HF bands, and it's a common general-purpose length that an antenna tuner can effectively match to the transceiver's output impedance, enabling reasonable radiation efficiency. Equipment instruction manuals often specify such lengths for emergency wire antennas. Options A and B (10 feet) are incorrect because 10 feet is electrically too short for efficient operation on most MF-HF frequencies. While a tuner might create a match, the antenna would be highly inefficient, resulting in very poor radiated power and severely limited range. Option D is incorrect because a VHF antenna is designed for frequencies much higher than MF-HF (e.g., 156-162 MHz). Connecting an MF-HF transceiver to a VHF antenna would create an extreme impedance mismatch, leading to negligible power radiation and potential damage to the transceiver.