Frequency Selectivity Analysis Based on Inductively Coupled Channel for Current Transmission Through Seawater

Inductively coupled channels are based on the electromagnetic induction principle and realize long-distance current signal transmission through seawater. Due to a few difficulties in performing actual experiments, it is unclear how the seawater medium affects the frequency selectivity of the current signal. In this paper, a dual dipole model of the inductively coupled seawater transmission channel is established for the traditional short-distance current field transmission mode. The transmission characteristics of electrical signals in seawater are theoretically derived. A platform is used to measure the amplitude-frequency and phase-frequency characteristics of the current signal transmission in seawater with transmission frequencies ranging from 30 kHz to 1 MHz, and transmission distances in the vertical range of 4 m. The COMSOL Multiphysics simulation and practical test analysis are carried out to analyze the frequency selectivity of seawater conductivity. It is proved that the seawater resistance increases as the frequency increases, which is the key problem that affects the current signal. This study provides an important theoretical support and experimental evidence for improving the transmission performance of long-distance underwater current signals.