Research on FDFD algorithm for mode propagation of extremely low frequency electromagnetic waveguide

This paper firstly deduces the Finite Difference Frequency Domain(FDFD) difference scheme of Maxwell’s equations in spherical coordinate system, secondly deduces the difference equation at the interface between isotropic medium and anisotropic medium in spherical coordinate system, and finally establishes the equation about the propagation of extremely low frequency electromagnetic wave in the earth-anisotropic ionosphere in MATLAB combined with the absorption boundary conditions and calculates the field intensity value. By comparing with the results of previous algorithms, it can be concluded that FDFD algorithm can meet the requirement of accuracy in calculating low-frequency electromagnetic wave propagation and the method is correct.