Application of z model in FDTD analysis of multi-layer conductivity slabs

The impedance boundary network condition (INBC) is widely used build parametric model of thin materials, fine mesh subdivision in finite difference time domain (FDTD) method can be avoided and the computational efficiency can be greatly improved. This paper proposes the z model method to describe the relations between the input and output in discrete time domain which have the relations between different equations and 1st-order rational fraction rational fraction. This modified calculation method could avoid complex convolutions and obtain exact results when the conductivity is low on the premise of the extractive estimation of z model. Example of a 3-D cavity containing a thin conductive layer on its bottom surface are used to prove the effectiveness of the proposed method.