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This paper presents an integrated approach to taking a frequency-domain simulation problem into the discrete time domain, based on z transforms. The ideas are illustrated with free space, the Drude pole, and perfectly matched layer (PML) conversion examples, for both leapfrog time stepping and simultaneous time stepping. Numerical results for various perfectly matched layer methods are given. We then present a two-dimensional scattering example in which the conversion from frequency to discrete time is carried out. Numerical results are presented and compared with results from a Method-of-Moments formulation. [ABSTRACT FROM PUBLISHER]

The finite-difference time-domain (FDTD) technique for simulating electromagnetic wave interaction with a dispersive chiral medium is extended to include the simulation of dispersive bianisotropic media. Due to anisotropy and frequency dispersion of such media, the constitutive parameters are represented by frequency-dependent tensors. The FDTD is formulated using the Z-transform method, a conventional approach for applying FDTD in frequency-dispersive media. Omega medium is considered as an example of bianisotropic media, the frequency-dependent tensors of which are based on analytical models. The extended FDTD method is used to determine the reflection and transmission coefficients of co- and cross-polarized electromagnetic waves from omega slabs, illuminated by normally incident plane waves. Three cases are simulated: 1) a slab of uniaxial omega medium with its optical axis parallel to the propagation vector; 2) a slab of rotated uniaxial omega medium with its optical axis not parallel to the propagation vector; and 3) a slab of biaxial omega medium. The results are validated by means of comparisons with analytical solutions. [ABSTRACT FROM PUBLISHER]

FDTD solutions have their own properties distinct from the discrete samples of corresponding continuous wave solutions. Thus, the discrete equivalent to the Green's function is needed for applications like the one using a hybrid absorbing boundary condition which couples the FDTD algorithm with integral operators for nonconvex scatterers. In this paper we propose a new closed-form expression for the 3-D dyadic FDTD-compatible Green's function in infinite free space via a novel approach with the ordinary z-transform along with the spatial partial difference operators. The final expression involves a summation of standing wave modes with time-varying coefficients. The propagation of waves in the Yee's grid can be interpreted by the selective property of the time-varying coefficients, which is very different from the conventional concept of a traveling wave. The traditional dispersion analysis using plane waves for the FDTD algorithm in a source-free region may not be applicable to explain the wave propagation phenomenon through our analytic expression, because the corresponding z-transform diverges for z on the unit circle. [ABSTRACT FROM AUTHOR]

The impulse-invariance z transform method has been used to discretize frequency-dependent dielectric functions for FDTD simulations. This paper reviews, generalizes, and compares several methods for improving the accuracy of this process. A slightly novel curve-fitting approach is presented for the dielectric function of silver. [ABSTRACT FROM AUTHOR]