Waveguide Filters Using Yttrium Iron Garnet Film

Theoretical and Experimental Investigation of Ferrite-Loaded Waveguide for Ferrimagnetism Characterization

“…We assume | H AC | H DC to ensure a perturbation effect of AC field on the dipole precession motion forced by the DC field. Since the dipole precession breaks the isotropic spatial symmetry, the susceptibility ( ↔ χ) that relates the additional magnetization ( M AC ) to the AC magnetic field ( H AC ) turns anisotropic [22][23][24][25][26]30]. Such susceptibility implies an anisotropic permeability (…”

“…When the operating band is far from the resonance and the stopband, for example from 8.50 GHz to 12.00 GHz, TE It is important to emphasize that the anomalous dispersion with high attenuation at 4.66 GHz-7.90 GHz would significantly reduce the strength of transmitting signal from the ferrite. This feature is useful for the applications in broadband filters or switches [23][24][25], however, such high loss would seriously increase the difficulty in measurement for ferrite characterization owing to the sensitivity limitation. On the contrary, the two special features for far-resonance operation from 8.50 GHz to 12.00 GHzthe normal dispersion and the weak attenuation, make this band more suitable for measurement.…”

“…On the other hand, rectangular waveguides partially or fully loaded with materials under test are frequently adopted for permittivity [18] and permeability [19][20][21][22][23][24][25][26] characterizations. Two major advantages are addressed here.…”

“…Nevertheless, as ferrite slabs were partially inserted, how to precisely locate their positions and how to exquisitely control magnetic-bias profiles become tough issues in real measurements. Alternative scheme was proposed in [22][23][24][25], in which a rectangular waveguide is fully loaded with a magnetized sample. This configuration is much easier to assemble with less error in sample's location and better control of bias field, superior to the partially loaded systems [20,21].…”

“…Although a model based on waveguide eigenmode expansion (mode matching) has been developed to solve scattering parameters, it cannot treat the case with ferrite due to high chromatic complexity in susceptibility. On the other hand, Tsutsumi et al studied the case with Yttrium Iron Garnet (YIG) ferrite film that was grown on a bulk substrate and then sealed by a waveguide [23,24]. An analysis method based on Fourier expansion (plane-wave expansion) was proposed for mode matching at boundaries.…”