Mode discriminators based on mode-selective coupling principle have a series of advantages. The designing method of this type of discriminator is presented in this paper. The emphasis is put 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-GHzgyrotrons, which can be applied to discriminate the TE 11 , TE 01 , and TE 02 modes and the TE 01 , TE 02 , and TE 03 modes, respectively, are given.