The influences of tensor parameters on the characteristics of microstrip structures on layered ferrite-dielectric substrates for phase shifter applications are investigated. By fully incorporating the permeability tensor into the numerical model, it is found that the propagation constant, and particularly the characteristic impedance values, are substantially lower than those commonly calculated under the scalar permeability assumption. The variation of the characteristic impedance is presented with respect to magnetisation levels, saturation magnetisations and the thickness of the ferrite layer.