Circumferential Gap in a TE01-Mode-Transmitting Multimode Circular Waveguide

Higher-order modes produced in a guide and fields radiated out of a guide by a circumferential gap in a multimode circular waveguide that is used for millimeter wave transmission, were investigated by means of fictitious equivalent magnetic current for the gap. These results were compared with the analysis obtained by Bethe´s method, which was used for the problem of diffraction of fields by a small hole in a plane conducting sheet. The two results agreed well for narrow gap.