Cutoff Wavenumbers and Modes of Hexagonal Waveguides

The first 21 normal modes and corresponding cutoff frequencies are obtained for the E modes of waveguides with regular hexagonal cross-sections. A previously developed numerical method, using inverse iterations, finite differences, and Richardson's mesh extrapolation procedure, is employed. The inverse iteration method is modified by an orthogonalization procedure to obtain the higher modes. A block factoring method is used to solve the finite difference equations. This combination of numerical techniques yields excellent accuracy and speed of computation.