实现极宽带相消干涉的物理机制研究及其在共形超表面隐身中的应用

Electromagnetic metasurface is an ultra-thin two-dimensional array composed of sub-wavelength unit cell. Through change and control the reflection phase of the unit cells, various forms of phase control schemes are formed to realize the non-directional scattering and achieve the RCS reduction. There are three main problems for metasurface in stealth applications: 1) The magnitude and bandwidth of RCS reduction is limited. 2) The study of stealth metamaterials is mainly confined to the planar structure. 3) Stealth problems of high-speed aircraft loaded with conformal antennas under large angle incidence. This paper focuses on the physical characteristics of the electromagnetic metasurface and its mechanism for the regulation of electromagnetic waves. Three kinds of destructive interference techniques are proposed, which include multiple-element destructive interference, bipolar destructive interference, reconfigurable destructive interference to greatly extend the bandwidth of RCS reducing and achieve 10 octave bandwidth of -10dB RCS reduction. And taking full account of the influence of the phase difference caused by the surface bending, these three destructive interference techniques are applied to realize extreme broadband stealth of the curved surface targets such as dihedral angle, triangular angle, cylinder surface, cone surface and spherical surface. Moreover, extreme broadband RCS reduction of high-speed aircraft loaded with antenna is also study and achieved by loading metasurface. The purpose of this project is to develop new stealth technology to meet the needs of defense equipment stealth, while forming a complete design set for conformal metasurface.

电磁超表面是由亚波长单元构造的超薄二维阵列平面，对超表面单元的反射相位进行改变和控制，形成多种形式的相位调控方案，实现电磁波的非定向散射，以达到RCS减缩的目的。目前超表面在隐身应用中存在三个主要的问题：1）实现RCS减缩幅度与带宽有限。2）超材料的隐身研究主要局限于平面结构。3）大角度入射下加载共形天线的高速飞行器的隐身问题。本项目重点研究电磁超表面的物理特性及其对电磁波调控的机理，提出三种相消干涉技术包括多元相消干涉、双极化相消干涉、可重构相消干涉来极大地扩展RCS减缩带宽，实现-10dB RCS减缩带宽达到10个倍频程。并充分考虑由于表面弯曲带来的周期单元相位差的影响，将上述相消干涉技术应用于实现二面角、三面角、柱面、锥面、球面等曲面目标的极宽带隐身。同时通过加载电磁超表面实现加载天线的高速飞行器的极宽带RCS减缩。以满足国防装备隐身化的需求，同时形成一套完整的共形超表面设计方案。

在本项目的资助下，研究了亚波长单元在平面波作用下的电磁响应特性，提出多种形式的相位调控方案，重点研究电磁超表面的物理特性及其对电磁波调控的机理，提出包括多元相消干涉、双极化相消干涉、缺陷栅格结构等多种新技术有效地突破了短路点和高阶模式造成的高频限制边界，极大地扩展RCS减缩带宽，设计了多种新型RCS超构表面，实现电磁波的非定向散射，以达到RCS减缩的目的，为发展新一代低RCS电磁超表面奠定重要的科学基础。