Susceptance-slope parameter of junction circulators

Abstract

The two quantities which define the performance of the junction circulator are its shunt conductance and its susceptance-slope parameter. It is shown in this paper that these two quantities are related in a universal way by the difference between the two split frequencies of the junction resonant modes. For many junctions, the difference between these frequencies is connected in a standard way to the magnetic splitting of the device. It is therefore sufficient to calculate either one of them to characterise fully the junction circulator. In this paper, the susceptance-slope parameter is calculated by forming the input admittance of the constituent resonator. The constituent resonator for the stripline circulator is the one formed by the ferrite disc fed by a single TEM line. It contains all the physical variables of the device. This principle is applied to a number of different geometries. The paper also describes a new quarter-wave-mode circulator.