Seawater Antenna Research Articles

Metal-Loaded Seawater Antenna With High Radiation Efficiency and Wideband Characteristics

In this letter, a high-radiation-efficiency and wideband seawater antenna is proposed. A square metal patch feeding mechanism is adopted, which improves the radiation efficiency from 45%–60% to 65%–70% and maintains wideband characteristics with a $-$ 10-dB impedance bandwidth of 67.6% (448–905 MHz) of the seawater antenna. Moreover, four cylindrical metal rods surrounding the feeding probe are inserted into the seawater, which further improves the radiation efficiency from 65%–70% to 82%–90% over the whole frequency range of interest. Furthermore, measured results of the fabricated seawater antennas with and without metal-loading techniques are compared, which show a good agreement with the simulated results and validate the proposed antenna design.

A Broadband Hybrid Monopole-Dielectric Resonator Water Antenna

A broadband hybrid water antenna operating at very high frequency (VHF) band is presented, in which a simple seawater monopole is loaded with two distilled water cylinders working as dielectric resonators (DRs). By employing the loading technique, multiple close resonances are introduced to broaden the impedance bandwidth of the seawater antenna. The hybrid water monopole-DR antenna is designed, simulated, fabricated, and measured. The simulated and measured results have a good agreement. A wide bandwidth from 69 to 171 MHz for $| {{{S}_{11}}} | is achieved. Meanwhile, the radiation patterns are stable in the desired band, which indicates that the proposed antenna is suitable for broadband application in VHF band communications.

High-Efficiency Sea-Water Monopole Antenna for Maritime Wireless Communications

This paper presents a study of sea-water monopole antenna at very high frequency (VHF) band for maritime wireless communications. The sea-water monopole antenna consists of a feeding probe and a sea-water cylinder held by a clear acrylic tube. The feeding probe is loaded with a disk on the top to improve the excitation of TM mode. A theoretical study of the sea-water monopole antenna based on the three-term theory is presented, which has not appeared in literature. Commercial software packages ANSYS HFSS and FEKO are used to simulate this antenna. Experimental results of a fabricated sea-water monopole antenna with a radius of 50 mm show reasonably good agreement with theoretical predictions. Measurement shows that the proposed sea-water antenna has high radiation efficiency. Meanwhile, due to the transparency and liquidity of sea water, the proposed antenna is almost optically transparent and can be easily reconfigurable. The center frequency of the antenna is tunable by lengthening or shortening the water cylinder, while the bandwidth of the antenna can be adjusted by widening or narrowing the water cylinder.

Sommerfeld integration for arbitrary, multi‐layer dielectric systems: a practical method for seawater antenna modelling

We present a formulation of the Sommerfeld integration method to calculate antenna radiation in an arbitrary stack of dielectric slabs. In the past, Sommerfeld integration, in the method of moments, has been used only for two semi-infinite layers (the lower layer often referred to as a groundplane). Here, we have returned to Sommerfeld's original formulation to extend the method for an arbitrary number of layers. When coded, our algorithm gives accurate results as proved by comparison to other simulations and approximate analytical formulas. Our motivation is to calculate antenna coupling in a seawater environment at ultra low frequencies, taking account of seawaves at the seabed and water surface. This is an important problem in marine engineering which cannot be address by finite element methods owing to the high apsect ratios and 106-order jumps in complex permittivity across the different layers. As well as validating the algorithm for multiple layers we show results from a realistic air/sea/seabed setup. We demonstrate that, if the antenna is close to the seabed, surface waves can form on the sea/seabed interface as well as the air/sea interface potentially improving reception.

The Numerical Simulation of Electrical Characteristic for a New Material Antenna

The traditional antenna is made up of metal or solid dielectric material, seawater is a new type of dielectric material for antenna. In this paper, numerical method (MoM) is used to calculate the input impedance of antenna formed by seawater, we compare its performance with traditional metal antenna while their radius and heights are changed, discuss its effect of input impedance and get the meaningful results, raise the application prospect of seawater antenna at the end of this paper.