Estimation of electromagnetic field in air by a magnetic dipole in the sea based on a current sheet model

摘要

Considerable efforts have been made to investigate the electromagnetic (EM) field in air produced by a magnetic dipole in sea. The conventional methods for this investigation mostly involve complicated analysis of Sommerfeld-type integrals. To conveniently provide a meaningful physical explanation of the EM field radiation in a two-layered media, this study considers a current sheet at the sea-to-air interface created by an underwater magnetic dipole. This current behaves like an antenna located on the surface and creates a wave that propagates through the atmosphere. Analysis of this current sheet can take advantage of the Huygens–Fresnel principle. The results using this approach can be verified by previous calculation and experiments on the sea, and show good agreement with experimental data. The present approach, which involves simple algebra, can easily explain the physical aspect of the EM wave propagation across the sea-to-air interface.