== Static Modeling Methods ==
Static or quasi-static approximations of Maxwell's equations can be reliably applied in two different scenarios: at low frequencies from DC to a few Megahertz, or when the total electrical size of your physical structure is a fraction of the wavelength , and wave retardation effects are negligible. In the latter case, your physical structure is effectively considered as a lumped device. Under those conditions, the electric and magnetic fields decouple from each other. Electric fields can be computed from charge sources or their equivalents and magnetic fields can be computed from current sources or their equivalents.
Under the static assumptions, Maxwell's equations reduce to elliptic partial differential equations known as the Poisson and Laplace equations. These equations can be solved analytically only for a few canonical geometries with very simple boundary conditions. For most practical and realistic problems, you need to utilize a numerical technique and seek a computer solution. The Poisson and Laplace equations can be solved numerically using the finite difference (FD) method.