Waveguide Structure Compatible with TE, TM, and TEM Modes

We propose a novel waveguide structure capable of supporting three different transmission modes, namely, TE, TM, and TEM. It can thus be used both above and below a cutoff frequency. Therefore, it can be used for super-wide band applications. The divided structure of the waveguide realizes transmission under a cut-off frequency in TEM mode, as well as by making use of the waveguide functionality. In addition, it can transmit in TE and TM (waveguide) modes in the same way as a typical waveguide with low loss. Transmission both under and over the cut-off frequencies was confirmed both through simulation and by practical experiments with the proposed waveguide. We also addressed the connector structure necessary for the associated waveguide-coaxial conversion.