Compositional designing of effective graded radar absorbing material for low observable technology is always a challengeable task in material science. The micro scale or quantum scale interaction of electromagnetic radiation is depends on the characteristic property of each atom or their assembly in a material composition. The filler and matrix in a composite structure plays a vital role between the advantages in electromagnetic absorption capability and the disadvantage due to difficulties in practical homogenous dispersion with weight concentration. The present work describes synthesis of biomaterial based effective graded radar absorbing material (RAM) for application in stealth technology. Ultrasonic treated rice husk raw material shows a significant increase of dielectric property of the composite material blended with epoxy resin. The significant modification in surface of the biomaterials with ultrasonic wave provides the enhanced mechanical strength as well as hardness of the material. Bio ceramic material composed of china clay and carbon rich waste rice husk ash possesses good dielectric loss for frequency 10 GHz and reflection loss -24.5 dB which is quite significant for stealth technology. Scanning electron microscopy (SEM) study shows good dispersion of rice husk ash in the epoxy matrix. Frequency dependence of both dielectric constant and dielectric loss are measured in the X band frequency range (8.2-12.4GHz). This low cost laboratory scale synthesized RAM find its application in designing of stealth aircraft and jet fighter for military purposes.

中文翻译：

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低可观测技术有效梯度微波吸收材料的设计与分析

用于低可观测技术的有效梯度雷达吸收材料的成分设计在材料科学中始终是一项艰巨的任务。电磁辐射的微观或量子尺度相互作用取决于每个原子的特性或它们在材料成分中的组装。在复合结构中的填料和基体在电磁吸收能力的优点与由于在重量浓度下实际均匀分散的困难而导致的缺点之间起着至关重要的作用。本工作描述了用于隐身技术的基于生物材料的有效渐变雷达吸收材料（RAM）的合成。超声处理过的稻壳原料显示出与环氧树脂共混的复合材料的介电性能显着提高。超声波对生物材料表面的显着改性提供了增强的机械强度以及材料的硬度。由瓷土和富含碳的废稻壳灰组成的生物陶瓷材料在10 GHz频率下具有良好的介电损耗，而反射损耗为-24.5 dB，这对于隐身技术而言非常重要。扫描电子显微镜（SEM）研究表明稻壳灰在环氧基质中具有良好的分散性。在X频带频率范围（8.2-12.4GHz）中测量了介电常数和介电损耗的频率依赖性。这种低成本的实验室规模的合成RAM在军事用途的隐形飞机和喷气战斗机的设计中得到了应用。