Mode chart and susceptance slope parameter of an E-plane circulator using coupled prism resonators

A three-port E-plane circulator may be constructed by placing either a pair of quarter-wave long cylindrical or prism resonators open-circuited at one end and short-circuited at the other in the H-plane of its junction. In the paper, the mode chart of the prism resonator arrangement is developed, and measurements on its susceptance slope parameter are taken. Since there is more than one solution that will meet the midband frequency of this sort of circulator, the susceptance slope parameter is not single valued. Knowledge of these two quantities satisfies the first classic circulation condition of the device