加载高介电薄层的宽带频率选择表面吸波材料设计与制备研究

Design and fabrication of a wideband frequency selective surface absorber loaded with a high dielectric thin layer

设计仿真并实验验证了一种加载高介电薄层的宽带频率选择表面吸波材料,该吸波材料由FR4介质板、电阻损耗型频率选择表面、聚氨酯泡沫和金属背板组成.仿真结果表明,该吸波材料对入射电磁波在3.6-24GHz频段范围内具有90%以上的吸收效果,且具有极化无关和宽入射角的吸收特性.加载高介电薄层的频率选择表面吸波材料的相对带宽能够达到带宽极限的58.0%,较未加载高介电薄层的优化带宽增加了11.0%,证明了加载高介电薄层有利于从结构上改善材料的吸收带宽.同时,通过Smith圆图从阻抗匹配的角度进一步分析论证了加载高介电薄层有利于在更宽的频段范围内提升吸波材料与空气的阻抗匹配程度,从而实现宽带强吸收.该吸波材料电磁结构与夹层复合材料的力学结构非常类似,便于实现吸波与力学性能的兼容,具有一定的工程应用价值.

A wideband frequency selective surface(FSS)absorber loaded with high dielectric thin layer was designed,simulated and tested.The proposed absorber was consisted of FR4 dielectric substrate,resistive FSS,polyurethane foam and ground plane.The results indicate that the absorber has a strong absorption more than90%from 3.6to 24 GHz,and was polarization-independent and incident-angle-insensitive.The achieved bandwidth of our absorber reaches 58%of the theoretical limit,showing the enhancement of 11%compared with the absorber without a high dielectric thin layer.Furthermore,the absorption mechanism has been analyzed from the view point of impedance matching.The electromagnetic configuration of the proposed absorber was similar to that of the sandwich structure composites which have been widely used in the engineering fields.As a result the proposed absorber has potentials in the design of advanced composites with absorbing as well as mechanism properties.