EM3DS, a full-wave simulation tool, fully 3D yet tailored for
quasi-planar structures, suitable for EM analysis of MEMS, in
particular MEMS switches. It uses a new MoM-based approach
(Generalized Transverse Resonance-Diffraction GTRD), claimed to avoid
the aspect-ratio limits of finite elements techniques. 60-day trial
version free for download, as well as a completely free (but
functionally limited) version.