A Sea-Water Antenna with Detached Feeding Structure

This paper presents a liquid HF antenna fed by a detached feeding structure. The feeding structure consists of a ferrite core, coil windings and shielding shell, which provides an inductive coupling for the monopole antenna. By dynamically tuning the water tube height, the antenna covers a wide range from 13 MHz to 18 MHz ($\mathrm{S}_{11}<-10 ~\text{dB}$), and achieves 25 % total efficiency. Simulations are performed and results show that the permittivity and the coling widings of ferrite core are important for the antenna efficiency. The proposed antenna exhibits omnidirectional radiation patterns and requires no soldering during installation.