Finite-difference frequency-domain method

The method is capable of incorporating anisotropic materials, but off-diagonal components of the tensor require special treatment.

An early description of a frequency-domain response FDTD method to solve scattering problems was published by Christ and Hartnagel (1987).

[3] Another is to find the normal modes of a structure (e.g. a waveguide) in the absence of sources: in this case the frequency ω is itself a variable, and one obtains an eigenproblem

An early description of an FDTD method to solve electromagnetic eigenproblems was published by Albani and Bernardi (1974).

Unlike the FDTD method, there are no time steps that must be computed sequentially, thus making FDFD easier to implement.

The FDFD method requires solving a sparse linear system, which even for simple problems can be 20,000 by 20,000 elements or larger, with over a million unknowns.

This can be circumvented by either using a very fine grid mesh (which increases computational cost), or by approximating the effects with surface boundary conditions.

Perfectly matched layer (PML) boundary conditions can also be used to truncate the grid, and avoid meshing empty space.

The FDFD method has been used to provide full wave simulation for modeling interconnects for various applications in electronic packaging.