Technical memorandum: Analysis of electromagnetic systems by means of fourier transform techniques

We have developed a method for calculating eigenfrequencies and field distributions for the modes of waveguides and resonant cavities The core of the method is the application of Fourier transforms to a time-domain solution of Maxwell´s equations. For quasi-one-dimensional systems we find a convergence criterion relating the spatial and time mesh widths which makes it extremely convenient. Finally, we have applied the method to two simple cases the homogeneous and the partially homogeneous parallel plane waveguides.