Electromagnetic field radiated from a horizontal magnetic dipole immersed in seawater based on complex image theory

摘要

Shaft frequency electromagnetic (EM) field (1~7Hz) corresponding to corrosion is an inherent attribute of the vessels and can be viewed as a primary signal source for underwater target detection and identification. In this paper, we investigate the propagation characteristic of shaft frequency EM field radiated from a horizontal magnetic dipole immersed in the seawater. A novel vector potential method based on complex image theory is proposed to derive the electric component of EM field in three-layered conducting media. Each term of the expression represents certain propagation path, thus the physic characteristic is clarity. In addition, theoretical analysis and experimental result are compared to estimate the effect of each propagation path on total field intensity at observation point.