FINITE ELEMENT METHOD FOR THE COMPUTATION OF THE ELECTROMAGNETIC FIELD OF WAVEGUIDES

The electromagnetic field of waveguides is customarily derived from an electric or magnetic vector potential. A functional may be written for the potentials which attains extrem value if the vector potentials satisfy the wave equation. The studied region is subdivided into triangles within which linear approximation is employed. In the present case the integral in the functional can be written in an analytical form. Having sought the extremum and taking the different boundary conditions of TM and TE modes into account, a set of linear equations is obtained. The unknowns are the nodal vector potential values. The set is solved by computer, and the method is illustrated by examples.