Explanation: GMDSS MF/HF antenna systems operate at significant power levels and use 50-ohm coaxial cable. The **PL-259 connector** (often called a UHF connector) is a standard, robust connector designed for just these applications. It handles power well, is relatively easy to install, and is widely adopted in amateur, commercial, and marine radio for HF, MF, and lower VHF frequencies. Its impedance characteristics are suitable for general 50-ohm use, despite its "UHF" name. Conversely, the "F" connector is a 75-ohm connector primarily used for television and cable systems, not high-power 50-ohm radio. The "SMA" connector is a sub-miniature connector designed for much lower power and higher frequencies, typically found on handheld radios or Wi-Fi devices. The "EIA-232" connector is a multi-pin serial data connector, not an RF connector for antenna systems at all.