Calculation of the electromagnetic fields generated by DC horizontal current element in semi-infinite space of seawater

Ship is constructed by steel and induces electromagnetic field when ship moves across the Earth´s magnetic field. This electromagnetic field is very important object characteristic of ship. In this paper, a simple method is proposed, the electromagnetic field expressions in seawater for DC horizontal current element located in air half-space and immersed in seawater half-space respectively are derived by using the classical Sommerfeld Hertz vector. The method is simpler than Wait´s and Bannister´s. This study is theoretical basis of further research on the electromagnetic field of ship moving across the geomagnetic field in seawater.