Criteria for phase shifter operation of an azimuthally magnetized coaxial ferrite waveguide

Three criteria: a physical, a mathematical and a functional one for operation of the coaxial waveguide, completely filled with azimuthally magnetized ferrite, under for normal TE01 mode excitation, as a digital nonreciprocal phase shifter, are established. The first of them is deduced from the phase characteristics of configuration and determines the limits of the interval in which it provides differential phase shift for a specific value of the off-diagonal ferrite permeability tensor element. The second criterion associates the structure parameters with certain roots of its characteristic equation, expressed by complex confluent hypergeometric functions and with the related to them positive real L(c,ρ, n) numbers (c=3D 3, 0<ρ<1, n=3D 1). The third one specifies the limits of the domain of phase shifter operation. These are functions, representing in normalized form the dependence of phase shift at the cut-off frequencies and at the envelope lines, marking the end of the phase curves for negative ferrite magnetization from the side of higher frequencies, on the guide radius for a fixed central conductor thickness.