Mesh wave impedance concept in FDTD technique

A new mesh wave impedance (MWI) that characterises the properties of waves travelling along the along the mesh according to the FDTD technique is defined and the formulas are derived in plane wave and two-dimensional cases. The MWI depends on the parameters of both the medium (μ, ɛ) and the mesh (cell size Δ, time step Δt), as well as the frequency. The wave reflection coefficient that occurs at the interface of two meshes with different mesh wave impedances have been obtained. Numerical examples have verified the mesh wave impedance concept and the reflection coefficient formula.