Impedance characteristics and radiation efficiency of partially submerged antenna in seawater

In view of the radiation performance of buoy antenna in the marine environment, based on the characteristics of the high attenuation in short-wave and ultra-short-wave frequency bands in seawater, this paper proposes an assumption that the antenna is divided into two parts, the water and underwater, using the sea surface as the interface, and an antenna model that is partially submerged in seawater is established. Based on the theoretical calculation model of the antenna in seawater, the hypothesis and the model are verified by carrying out the antenna input impedance test experiment. Using the model, the working frequency range of the underwater part and the underwater impedance conjugate matching conditions are determined, and how the length of the underwater part and the dielectric parameters of the insulating layer affect the radiation efficiency are analyzed. The results show that the effective radiation of the buoy antenna can be achieved by adjusting the antenna frequency, the impedance of the antenna tuner, the material and thickness of the insulating layer, and so on, thus, providing support for marine electromagnetic wave communication.