Micro-wave Absorbing And Electromagnetic Shielding Properties Of Ferromagnetic Glass-covered Amorphous Micro-wires

In this paper, the absorption capability and electromagnetic shielding performance of a Co-based glass-covered amorphous micro wire has been studied based on the transmission network vector analyzer/reflection method.In this study, the amorphous micro wire was filled to the test samples as the absorbent. The absorbing property of the amorphous micro wire was marked with the reflectivity of the testing sample to electromagnetic wave. Firstly, the electromagnetic parameters of the glass-covered Co69Fe6Si12B13 amorphous micro wire was tested in the range of 2~18 GHz frequency. Secondly, based on these parameters, the reflectivity of the testing samples was computed by using the MATLAB simulation method. Thirdly, the absorption capability of the testing samples of different filling ratio was worked out. The result shows that, With the filling ratio of ferromagnetic amorphous micro wire increases from low to high, the complex-magnetic permeability basically remain the same, and the complex-dielectric constant of real part and imaginary part increase obviously, so the ferromagnetic amorphous micro wire is kind of dielectric loss of absorbing material. And, when the filling ratio is up to 20%, the reflectivity is the lowest, it reaches 1.2dB. So, the 20% filling ratio is the best for absorbing ability of amorphous micro wire.In this paper, the electromagnetic shielding performance of the amorphous micro wire is characterized by the transfer rate in two-port network S parameters. In the experiment, the electromagnetic shielding effectiveness has been investigated according to arranging style, arranging density, with glass layer or without the glass layer, and annealing processing and other influencing factors respectively. The result shows that, The results show that the longitudinal arrangement are better than the horizontal, closely spaced better than loosely arranged, and when the amorphous micro wire samples are arranged in 1mm longitudinal spacing, the shielding effectiveness reaches the best value of 37 dB. Comparing the shield performance with the pure copper wire, the amorphous micro wire shows better shield effectiveness in more than 10 GHz high frequency band. As for the wires with and without the glass coating, the result shows that the former is better than that of the later. Comparing the shield performance with Fe-based glass-covered amorphous micro wire,the Fe-based amorphous micro wire shows better shield effectiveness in less than 12 GHz frequency band, the Co-based glass-covered amorphous micro wire shows better shield effectiveness in 12~18GHz frequency band. After an annealing at 500℃, the amorphous micro wire shows an excellent electromagnetic shielding performance, due to the obvious improvement of the soft magnetic properties.