A high precision modeling and calculation method of ship shaft frequency electromagnetic field based on electric dipole

Shaft-rate electromagnetic field is a kind of signal with obvious electromagnetic characteristics in the physical field of ships. Therefore, the study of shaft-rate electromagnetic field is of great significance to ship electromagnetic protection. Based on the Maxwell's equations in the electromagnetic field theory and the two-layer media conditions of air and seawater as the background to derive the approximate analytical expressions of the electric and magnetic fields generated by horizontal time-harmonic electric dipoles and vertical time-harmonic electric dipoles in seawater. This paper used MATLAB to calculate the electric and magnetic field distribution in 10m and 50m seawater. Finally, a simple edge current model of two-layer dielectric was built in COMSOL without affecting the accuracy of the calculation. The comparative analysis results show that the derived formula can calculate the electric field and magnetic field at different depths in seawater. The analytical solution accuracy of the electric field intensity X and Y components of the horizontal electric dipole is higher, the analytical solution accuracy of the electric field intensity Z component and the three components of the magnetic flux density is higher. The calculation accuracy of different components using different analytical solutions can reach up to 96%.