The animation is meant to illustrate the periodic power transfer between two adjacent, evanescently coupled parallel waveguides. The frames show the local intensity on cross section planes (the black lines indicate the permittivity boundaries) at different positions on the propagation axis. Note that this concerns stationary fields; the time coordinate of the animation replaces the propagation distance. The gif-image was generated via MATLAB by the direct m-file output of the WMM programs. See the WMM-Manual for a detailed description.