Magnetic properties of diluted ferrites near ferromagnetic resonance in millimeter waves

Transmittance measurements on diluted barium ferrite materials in broadband millimeter-wave frequency range have been performed. The measurements have been done using free-space quasi-optical spectrometer in transverse magnetic field up to 7.5 kOe. A set of backward wave oscillators have been used as sources of high power coherent radiation tunable in 34-120 GHz frequency region. A magnetooptical approach has been employed for the separation of dielectric and magnetic effects in ferrites and simultaneous determination of complex dielectric permittivity and magnetic permeability of materials. It has been shown that a variation in the chemical composition of ferrites leads to a change in the magnetic properties and absorption of materials in the millimeter waves.