Dielectric and permeability effects in HE111 open demagnetised ferrite resonators

The half-wave HE111 open ferrite or dielectric resonator, open circuited or loaded by image walls at each end, is a common building block in the construction of waveguide circulators and other devices. Its resonant frequency is usually evaluated by catering for the image wall effect but neglecting that of the open lateral wall. The latter omission is largely reconciled in this paper by employing an equivalent waveguide model for the resonator which has the same radius as the original but with an effective instead of the constitutive dielectric constant. The import of the diagonal element¿¿d of the demagnetised resonator is separately catered for.