Investigation of Complex Permittivity and Permeability of Ferrimagnet in Millimeter Waves

In order to investigate the dielectric and magnetic parameters of soft ferrimagnet in millimeter waves, several yttrium iron garnet (YIG) and hexagonal ferrite ceramic (HFC) are measured. The complex permittivity and permeability of the YIG and HFC have been obtained in a broad-band spectrum. Measurements are realized by using a broad-band quasi-optical millimeter-wave system with a backward-wave oscillator as the source of tunable coherent radiation. Moreover, the alternating-direction-implicit finite-difference time- domain method has been used to simulate the YIG and HFC models. The experiment results are in good agreement with the numerical curves. It is shown that these results provide an accurate characterization of soft ferrites as well as hard anisotropic ferrites in the entire millimeter-wave range.