Papers by Author: Chao Wu

Abstract: Two methods are widely used to improve absorbing properties of the microwave magnetism absorbing agent: mixing with the other material such as resistance carbon fiber absorbent, or wrapping the microwave magnetism-absorbing agent in that material. However, do these two methods coincide with each other If not, which method should be used as better way to represent the absorbing properties of magnetism-absorbing agents To answer these questions, both methods are carried out on the same magnetism absorbing agents, of which the results are compared. Distinct difference between these measured results is found, and the possible reasons for the difference are also discussed.

Abstract: Microwave diffraction behavior of microwave absorbing ceramics was investigated by numerical calculation, and effective electro-magnetic parameters of the ceramics was obtained by comparing the diffraction behavior with that of homogeneous material. Then, the calculated results were compared with the results of effective medium models, aiming to investigate the applicability of these models. The obvious difference between these results were pointed out, also discussed is the possible reason for this difference.

Abstract: In order to compare the absorbing properties of different microwave-absorbing agents and their mixture, this paper has selected two typical microwave-absorbing agents which respectively are carbon fiber resistance microwave-absorbing agents and ferrite magnetism microwave-absorbing agents, and took them as monolayer absorbing materials. Then used MG formula to calculate the effective electromagnetic parameter of their mixture under different proportion at X band, and finally analyzed their absorbing properties separately. Then through contrasting the impedance matching characteristic and attenuation coefficient of the materials, it is proved that adding carbon fiber in ferrite can not improve absorption properties. Although the ability of attenuating electromagnetic wave would be enhanced when resistance materials and magnetism materials are blend with each other, doping will destroy the materials’ impedance matching characteristic because most resistance materials have high permittivity. It makes reflection strengthen and can not improve absorbing properties.

Abstract: In order to improve absorbing properties of material effectively, enhance the ability of attenuating electromagnetic wave, and at the same time, make the impedance matching with air to the most extent, this paper mixed ferrite magnetism microwave-absorbing agents with semiconductor particulates. We got the effective EM parameter of the mixture using effective EM parameter model, and then analyzed absorption properties. As the result, it figured out the cubage proportion and conductance of semiconductor particulates based on the resistance matching principle. Through calculating the reflection ratio、impedance matching characteristic and attenuation coefficient of the material, it is proved that mixing ferrite magnetism microwave-absorbing agents with semiconductor particulate which has less permittivity could reduce real complex permittivity and increase imaginary complex permittivity of the composite material. It was able to enhance the ability of attenuating electromagnetic wave, improve absorbing properties, and meanwhile do not destroy the impedance matching characteristic with air.