What is the antenna requirement of a radiotelephone installation aboard a passenger vessel?

• A. The antenna must be vertically polarized and non-directional and efficient as practicable for transmission and reception of ground waves over sea water
• B. The antenna must be horizontally polarized and highly directional
• C. The antenna must be circularly polarized and highly directional
• D. The antenna can be any polarization and directionality

Answer: (A)

For a radiotelephone installation on a passenger vessel, the antenna is specified to be vertically polarized and non-directional, with efficiency as practicable for transmitting and receiving ground waves over sea water. Vertical polarization aligns well with how ground waves travel along the sea surface, providing better coupling to the sea and more reliable reception over typical maritime distances. A non-directional pattern ensures that the signal radiates evenly in all horizontal directions, which is important for a moving vessel that may approach or depart from stations from any bearing. This combination also reflects the practical goal of getting the most reliable communication possible given space and installation constraints.

Horizontal polarization or highly directional patterns would either reduce compatibility with the sea-ground wave propagation or require precise aiming, which isn’t suitable for general shipboard use. Circular polarization isn’t required for this application, and allowing any polarization and directionality would undermine the broad, dependable coverage needed at sea.