Complex permittivity and permeability measurements of ferrimagnets at millimeter waves with high power sources

We present complex dielectric permittivity and magnetic permeability characteristics of strontium and nickel ferrite ceramics in Q-, V-, and W-band frequency range. The measurements have been done using broad-band quasi-optical millimeter wave spectrometer with backward-wave oscillator as a high power source of coherent radiation. Dielectric and magnetic parameters of the ferrite ceramic materials have been calculated by employing the best fit of the theoretical curves to the experimental transmittance spectra.