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.