Research of extremely low frequency to magnetic dipole in seawater media

The corrosion and anti-corrosion current of the submarine will produce extremely low frequency (ELF) electromagnetic (EM) field after modulated by the propeller rotation in the seawater. It becomes one of the most important characteristics of the signal source. A set of mathematical expressions based on certain assumptions and simplification can be formulated from a simplified model of three-layered conducting media (air-seawater-seafloor), which is based on electric vector potential. The simulation results show that the intensity of EM field has a great location when it is the shaft-rate electromagnetic (SREM) field. So it can be received in a long distance throughout the shaft-rate range. And the slower Submarine´s speed is, the larger the intensity of EM field is. The approach is effective for the research of ELF wave propagation in layered media.