In [[EM.Cube]]'s [[FDTD Module]], a dielectric material represents a general isotropic material with both electric and magnetic properties. The constitutive [[parameters]] of a dielectric material include permittivity (ε), permeability (μ), electric conductivity (σ) and magnetic conductivity (σ<sub>m</sub>):
[[Image:FDTD17.png|300px]]
where '''E''' and '''H''' are the electric and magnetic fields, respectively, '''D''' is the electric flux density, also known as the electric displacement vector, '''B''' is the magnetic flux density, also known as the magnetic induction vector, and '''J '''and '''M '''are the electric and magnetic current densities, respectively. For example, an imperfect metal can be represented by a dielectric material that has a large, finite, electric conductivity. PEC and PMC, therefore, are the limiting cases of an isotropic dielectric material when σ → ∞ or σ<sub>m</sub> → ∞, respectively.