基于磁性衬底的宽频薄层超材料吸波体研究

首先设计了由优异阻抗匹配的匹配层和高损耗的吸收层组成的磁性衬底,其次通过中间添加一层优化的频率选择表面调节其在不同工作频段的损耗和阻抗匹配,进而实现宽带薄层高效吸收。结果表明,所开发设计的吸波体具有极其优异的吸波性能,在厚度为2.5 mm时,其反射损耗峰在3.5~17 GHz均达到−10 dB,有效吸收带宽为13.5 GHz;相比于传统的单层吸波体,其损耗性能和阻抗匹配明显改善。因此,通过设计由磁性衬底和频率选择表面组成的超材料吸波体更有利于获得宽带薄层雷达吸波体,对于解决当前高端电子设备和先进武器装备所急需的高效吸波体提供了切实可行的解决方案。

Microstructure and magnetic properties of CoFe_2O_4 thin films deposited on Si substrates with an Fe_3O_4 under-layer

The microstructure and magnetic properties of cobalt ferrite thin films deposited by the sputtering method on an Fe3o4 un- der-layer were investigated at different post-annealing temperatures. Results show that the Fe3o4 under-layer can accelerate the grain growth of cobalt ferrite films due to the phase transformation of the Fe3o4 under-layer at about 400℃-500℃. By intro- ducing the Fe3O4 under-layer, cobalt ferrite nanocrystalline thin films with high coercivity can be obtained at lower post-annealing temperatures.