Synthesis of quarter-wave coupled junction circulators using moderately magnetised disc resonators with commensurate eigennetworks

A classic solution met in the theory of a junction circulator using a disc gyromagnetic resonator is the so-called tracking one for which the complex gyrator circuit displays a nearly frequency-independent gyrator conductance and a nearly constant susceptance-slope parameter over nearly an octave band. It is characterised by a tensor permeability with an offdiagonal element ?, 0.50 = ? = 1.0, a unique coupling angle, an inphase eigennetwork with an ideal electric wall at the terminals of the junction, and counterrotating ones with split conjugate reactances at the same terminals. Another useful solution is the so-called weakly magnetised one for which the gyrotropy is bracketed by 0 = ? = 0.30 but for which the solution is independent of the coupling angle. The paper investigates the complex gyrator circuit of this sort of circulator in the intermediate gyromagnetic interval defined by 0.30 = ? = 0.50. Each gyromagnetic interval is associated with a unique complex gyrator circuit with a distinct value of gain-bandwidth product or quality factor. A practical example of such a synthesis is included. © IEE, 1996.