Time domain analysis of inhomogeneously loaded resonators using eigenfunction expansion

An alternative time domain method for the analysis of dielectric loaded cavities is described. The method stems from the frequency domain approaches based on the field expansion employing entire domain basis functions. The field in the cavity is treated as a superposition of eigenfunctions of the homogeneous Laplace equation. Each field component is expanded into a series of scalar functions and at each time step one computes the expansion coefficients rather than field values at discrete nodes. An advantage of this approach is that it leads to time domain algorithms which allows for coarser time discretization