Fundamental investigation on a weakly magnetized ferrite absorber

Investigated are the matching characteristics of a magnetized ferrite absorber, which applies a weakly static magnetic field Hdc perpendicular to the sintered ferrite surface. Applying a static magnetic field to the ferrite enables the matching thickness of the absorber to be reduced from 8 mm in the absence of Hdc to 3 mm under 750 gauss. The matching frequency can also be changed broadly from 0.1 to 0.9 GHz by controlling ferrite thickness and Hdc, simultaneously. These are well explained in terns of an nonsaturated permeability rather than tensor permeability. A thin magnetized ferrite absorber is realized using a ferrite with a large value of imaginary part of permeability when real part takes the value near 1.0. Matching frequency characteristics, whether broad or narrow, correlates closely with the slant of the curve for real part of permeability taking the value near 1.0 in the present frequency