Modes of crossed rectangular waveguide

The cutoff frequencies and modal fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarizations when the guide dimensions are chosen appropriately. For applications where symmetric excitation is assured, bandwidths in excess of 2:1 can be obtained.