Preparation And Study On Radar Absorption Performance Of Fiber (Felt)/Epoxide Resin Circuit Analogue Composites

In this paper, silicon carbide fiber / epoxy composites and active carbon fiber felt periodical screen / epoxy composites were prepared by compress-molding techniques. In these composites, orthogonal-arranged SiCf circuit, orthogonal-arranged electroless-nikel-plated SiCf circuit and active carbon fiber felt periodical screen acted as radar absorbers. The factors that influencing radar absorption performance of the silicon carbide fiber / epoxy composites, such as fiber distance, carbon black content and electroless nikel plating of the fiber, were researched systematically; By means of changing the shape and the dimension of the carbon fiber felt periodical screen units, the radar absorption performances of the composites were studied. The results showed that radar absorption performances of the orthogonal-arranged SiCf circuit / epoxy composite were deeply affected by the distance between SiCf bundles. With the decrease of the distance between SiCf bundles, radar absorption performance was enhanced. When the distance was 2mm, a refection loss below -10dB over 9GHz bandwidth was obtained, and the maximum reflection loss was -19.4dB. Radar absorption performances of the orthogonal-arranged electroless-nikel-plated SiCf circuit / epoxy composite were deeply affected by the distance between SiCf bundles and the rate of weight growth of the nikel coating. With the increase of the distance or the rate of weight growth, radar absorption performance exhibited an increase and then followed by a decline. When the distance is 8mm and the rate of weight growth of the nikel coating is 283.3mg/g, a refection loss below -10dB over 4.5GHz bandwidth was obtained, and the maximum reflection loss was -24.3dB. Radar absorption performance of the orthogonal-arranged SiCf circuit / epoxy composite was not improved by adding carbon black. As for active carbon fiber felt / epoxy composites, radar absorption performance was not good when taking the massive carbon fiber felt as radar absorber, and a refection loss below -10dB within the range of 2-18GHz was not obtained. However, replacing the massive carbon fiber felt with the circuit analogue periodical screens as radar absorber, radar absorption performance of the composites was enhanced greatly within the range of 8-18GHz. The shapes of periodical units included rectangle, crisscross, equilateral triangle, annular square and maze square.