Research On The Structural Design And The Absorbing Properties Of Absorbing Plates

This paper studies on the absorbing properties of the monolayer composites of epoxy filled with Sb₂S₃(Antimony sulphide), MnO₂(Manganese dioxide), and CB(carbon black), as well as the absorbing properties of the bilayer composites of Sb₂S₃/CB, MnO₂/CB and CB/CB respectively.It is found by studying on the monolayer composites that the absorbing properties of the samples are slightly improved with the increase in the amount of the absorbent (Sb₂S₃, MnO₂, and CB). But when the amount of the absorbent reaches a certain level, the absorbing properties begin to decline, because the assembled particles lead to the inequality of the absorbent distribution and the decreased resistance matching between the surface of the composite and the air, which makes a large amount of electromagnetic waves reflected back to the open air. By studying on the absorbing properties of Sb₂S₃, MnO₂, and CB, it is found that Sb₂S₃ and MnO₂ belong to dielectric dissipation absorbent, while carbon powder belongs to resistance absorbent; they all have loss effect to the electromagnetic waves. By comparing the loss effect of the three kinds of absorbent with the same thickness and the same component ratio, it is found that the loss effect of CB is the most and that of Sb₂S₃ is the least. On this basis, bilayer absorbing materials with resistance gradual changing structure (absorbing layer+ matching layer) are made with CB as the absorbing layer and with Sb₂S₃, or MnO₂ as the matching layer. The electromagnetic parameter is controlled by the amount of the absorbent in the matching layer to achieve the resistance matching between the surface of the bilayer material and the air; the absorbing capacity is increased by changing the amount of the absorbent in the absorbing layer. The experiment adopts feasible methods and materials of small specific gravity; its costs are low and the effect is obvious. Findings show that in the frequency range 8～18GHz, when the values of the packing ratio of Sb₂S₃ is 15 vol.% in the matching layer, and the thickness of matching layer is 1.0mm; the values of the packing ratio of CB is 30 vol.% in the absorbing layer, and the thickness of the absorbing layer is 3.0mm, when the values of the packing ratio of Sb₂S₃ is 10 vol.% in the matching layer, and the thickness of matching layer is 1.0mm; the values of the packing ratio of CB is 35 vol.% in the absorbing layer, and the thickness of the absorbing layer is 3.0mm, the -10dB bandwidth of these samples is above 7GHz. When the values of the packing ratio of MnO₂ is 7 vol.% in the matching layer, and the thickness of matching layer is 1.0mm; the values of the packing ratio of CB is 34 vol.% in the absorbing layer, and the thickness of the absorbing layer is 3.0mm, When the values of the packing ratio of MnO₂ is 12 vol.% in the matching layer, and the thickness of matching layer is 1.0mm; the values of the packing ratio of CB is 30 vol.% in the absorbing layer, and the thickness of the absorbing layer is 3.0mm, When the values of the...