The electromagnetic properties of amorphous and nanocrystalline powdered Fe-Si-B-Cu-Nb alloy at microwaves

The electric and magnetic properties of the magnetically soft Fe-Si-B-Nb-Cu alloy (Finemet), as a candidate on the absorber at microwaves, have been studied in the frequency range from 0.2 to 10 GHz. Measurements were achieved with the use of the coaxial line technique, where the scattering parameters at broadband frequency range were determined. In this method, using the signal flow graph representation, a method of measuring of the powders inserted in between two plastic walls has been discussed. Based on this attempt, values of relative permittivity (ε´, ε”) and permeability (μ´, μ”) of the powdered amorphous and nanocrystalline Finemet were shown for four groups of powders with different particle sizes. The measured data refers to pure pulverized Finemet without insulating resin or wax. The obtained results show that the powdered nanocrystalline Finemet containing particles below 25 μm in diameter can have good shielding / absorbing properties (EMC).