基于超材料的吸波体设计及其波导缝隙天线应用

Design of metamaterial absorber and its applications for waveguide slot antenna

设计了一种基于超材料电磁特性的吸波体,并将其应用于波导缝隙天线.该吸波体是由两层金属及其中间的有耗介质组成,上层金属是由刻蚀交叉缝隙的贴片形成的电谐振器,下层金属不刻蚀,作为整个金属地板.通过优化结构参数,得到了一种极化不敏感、宽入射角的超薄吸波体,吸波率达到99.1%,厚度只有约0.01λ.将该吸波体应用与波导缝隙天线,在5.48—5.7 GHz工作频段内,天线雷达散射截面减缩都在3 dB以上,在鼻锥方向的-25°—+25°范围的角度上,天线雷达散射截面减缩均在5 dB以上,雷达散射截面减缩最大超过12 dB,而天线前向增益仅降低了0.53 dB.实验结果与仿真结果符合得较好,证实了该吸波体具有好的天线雷达散射截面减缩效果,可以应用于天线目标的隐身.

A metamaterial absorber is designed and applied to the waveguide slot antenna. The absorber is composed of two metallic layers separated by a lossy dielectric spacer. The top layer consists of etched oblique cross-gap patch set in a periodic pattern and the bottom one is of a solid metal. By fine adjusting the geometric parameters of the structure, we can obtain a polarization-insensitive, wide-incident-angle ultra-thin absorber that has an absoption of 99.1% and a thickness of only 0.01A. The absorber is applied to the waveguide slot antenna. The radar cross secction （RCS） of antenna is reduced by 3 dB or more in an the operation band from 5.48 GHz to 5.7 GHz, and by 5 dB or more in the boresight direction from -25~ to -I-25~, and the most reduction value exceeds 12 dB, but the forward gain of antenna reduces only 0.53 dB. The experimental results are in good agreement with the simulation results, which verifies that the absorer has a good characteristic of RCS reduction and can be applied to the stealth of antenna,