Characterizing and Testing a Fabric Containing Amorphous Glass-Coated Ferromagnetic Microwires for its Magnetic and Electric Shielding Properties in the Frequency Range (1-3) Ghz

Abstract

By applying a non-standardized methodology and by using electric- and magnetic-field probes of small dimensions (< 1cm), we experimentally characterized the electromagnetic shielding properties of a fabric containing ferromagnetic microwires weaved on a single direction. Electronic microscopy and X-ray spectroscopy revealed the structure, dimensions and chemical elements content of the amorphous magnetic material. Electric shielding factor proved to be very low in the investigated frequency range, but magnetic shielding factor was high, especially when the weaving direction of the magnetic wires corresponded to the polarization direction of the emitting antenna, and showed some resonances. The magnetic shielding efficiency, if checked against an increasing incident magnetic flux density, proved not to change up to 200 nT. The investigated fabric have been previously proved to be very efficient in shielding the field emitted by a mobile phone in its near field, but present results show that near and far field shielding properties are different.

Keywords

• electromagnetic shielding
• amorphous ferromagnetic wires
• near field probe
• magneto-impedance effect
• amorphous material microscopy