Studies of sea-state effects on antennas in shipboard communications

Abstract

The effect of sea surface conditions on the performance on antennas in VLF, HF and VHF shipboard communications is addressed. In the VLF range, towed buoyant cables are examined. The equations of force are derived & presented and the towed cable configuration is simulated on a hybrid computer. A method of calculating the received voltage is developed. The complexity of simulating a cable antenna in a real-world sea surface environment is addressed. HF shipboard antennas used in ionospheric communications systems are simulated on the hybrid computer and the effect of sea state is determined by calculating the time varying gain pattern of the antennas. Recommendations for antenna types which are less sensitive to sea state are made. A similar simulation conducted for a VHF radiator on a ship in typical sea conditions is compared with measured received signals.