基于多模谐振技术的超宽带Salisbury屏

Ultra Wideband Salisbury Screen Based on Multiple-mode Theory

微波吸收体在武器装备对雷达隐身方面具有重要的应用,受到学者们越来越多的关注,其中具有高带宽比的吸收体结构是研究的一个重要方向。多模谐振理论是滤波器设计当中常用的带宽展宽方法,本文将该理论用于超宽带Salisbury屏的设计当中,通过在Salisbury屏的介质隔层中引入感性接地面和多层有耗FSS,得到了具有高带宽比的低剖面微波吸收体;其中第二种方法采用的FSS阵列形状为普通的十字型偶极子阵列,主要是通过在其上加载贴片电阻来增强其有耗特性,从而改变偶极子阵列上的电流分布;在设计过程中,通过在Smith圆图上优化吸收体表面的阻抗轨迹,最终得到一种超宽带Salisbury屏,其相对带宽可达126%,而厚度仅为最低频率对应工作波长的五分之一左右。

Microwave absorbers play a great role in radar cloaking for weapons in the national defense area, which attract a lot of attention from academia, and high bandwidth ratio is an important character for absorbers. In the filter design, multiple-mode theory is a mature technology for the bandwidth enhancement. In this work, we use the multiple-mode theory to broaden the bandwidth of classical Salisbury screen, which is carried out by inserting lossy FSS into the dielectric layer, and can achieve ultra wide bandwidth. The lossy FSS is formed with cross dipole arrays, and we add chip resistors to increase the resistance, and therefore change the current distributions on the cross dipoles. The whole design is guided by manipulating the impedance locus of the screen on the Smith chart, and finally obtain a ultra wide band microwave absorber with a relative bandwidth of 126%, but the thickness is only a 1/5 wavelength of the minimum operating frequency.