Measurement of the radiation patterns of navy shipboard High Frequency (HF) antennas on a large warship

• The superstructure of a vessel modifies the VSWR of a HF whip onboard.
• Optimal placement for HF whips onboard a vessel is analyzed (VSWR and patterns).
• A method to measure HF radiation patterns onboard a shipboard is proposed.
• The VSWR of a HF folding whip changes with its position (vertical or horizontal).

Warships use strategic and tactical communications to be connected with national command headquarters and other units around the world. Therefore vessels need a communication system to be able to provide line-of-sight and long-haul communications. High Frequency (HF) communications can meet this requirement. Thus the ship needs to know the behavior of HF communications systems, for example, if they have any null in the radiation pattern. This article describes the measurements of the radiation patterns of HF whips in different places and with different polarizations (2–30 MHz) on a large vessel. Theoretically, HF shipboard antennas are close to be omnidirectional, so that the transmission and reception do not depend on where the ship is heading. We need to know the patterns at different frequencies first, to evaluate if the place where the antennas have been placed is adequate and second, to detect the possible nulls in the radiation pattern.