Mode discriminator based on mode-selective coupling

Mode discriminators based on a mode-selective coupling principle have a number of advantages. The design method of this type of discriminator is presented in this paper. The emphasis is placed on the mode-selective coupler with a multihole and multigroup of coupling holes. All of the dimensions of the discriminator are determined by this method. The calibration and power measurement of the discriminator are also investigated. Some design examples of discriminators for 35- and 70-GHz gyrotrons, which can be applied to discriminate the TE/sub 11/, TE/sub 01/, and TE/sub 02/ modes and the TE/sub 01/, TE/sub 02/, and TE/sub 03/ modes, respectively, are given.