Transmittance measurements on micro- and nano-sized ferrite powders in millimeter waves

Transmittance measurements on micro- and nano-sized powdered barium ferrite (BaFe
₁₂
O
₁₉
) and strontium ferrite (SrFe
₁₂
O
₁₉
) have been studied in a broadband millimeter wave frequency range for the first time. Measurements have been performed using a free space quasi-optical millimeter wave spectrometer, equipped with high power backward wave oscillators as sources of tunable coherent radiation. A tunable millimeter wave absorber based on micro- and nano-sized powdered ferrite materials is presented.