Higher order mode generation in millimeter wave regime by directly launched fundamental mode

We report on a novel method to generate higher order modes in the frequency range of millimeter and submillimeter wave regime. The method uses magnetic coupling scheme between waveguide fundamental mode and a cavity mode. A TE62 mode at W-band was considered for design using the proposed scheme. The suggested method simplifies a mode generator design allowing direct feeding via a standard fundamental waveguide and also provides a compact mode generator to design extremely higher order mode in a cavity. In addition, it opens a new and novel way to develop high power high gain gyrotron amplifiers at millimeter and submillimeter wave regime. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1648–1651, 2014