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中国物理学会期刊

基于散射相消机制的超表面天线罩带外RCS缩减特性研究

Reduction of out-of-band radar cross section for the metasurface-based radome mediated by the scattering cancellation mechanism

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  • 降低天线罩的带外雷达散射截面一直是隐身技术领域的研究热点,频率选择表面(FSS)或吸波材料是实现这一目标的常用手段,但前者受限于特殊形状要求,后者则因损耗介质的引入会产生插入损耗。本文提出一种基于散射相消机制的超表面复合材料,旨在实现带内高透波与带外宽带RCS缩减。该材料采用夹芯结构,由石英纤维/环氧树脂复合材料面板、PMI泡沫及FSS层组成,频率选择表面由两种结构单元组成,它们在通带外形成接近180°的反射相位差,从而将反射波导向至非镜面方向,从而有效降低目标RCS。实验结果表明,在垂直入射条件下,该结构在4~8GHz、12~18GHz宽带范围内RCS缩减大于10dB,在8~12GHz频段内透波率小于1dB。所设计的超表面复合材料结构简单、制备工艺简便、成本较低,在隐身天线罩领域具有广阔的应用前景。

     

    Reducing the out-of-band radar cross section (RCS) of radomes while maintaining high in-band transmission efficiency is a key technical challenge in electromagnetic stealth and antenna engineering fields. Conventional solutions rely on frequency selective surfaces (FSS) or microwave absorbing materials. However, FSS structures are often restricted to special curved shapes and difficult to apply in planar cases, and the absorbing materials introduce considerable insertion loss. Both solutions degrade antenna radiation performance. To address these limitations, this paper proposes a metasurface composite radome based on the scattering cancellation mechanism. The proposed design realizes broadband out-of-band RCS reduction and low-loss in-band transmission simultaneously without introducing any lossy medium. The proposed radome adopts a multi-layer sandwiched structure composed of quartz fiber/epoxy composite panels, low-dielectric foam core, and anisotropic FSS layers. Two types of FSS elements with orthogonal orientations are arranged in a chessboard configuration to generate a reflection phase difference close to 180° outside the passband, so that specular reflected waves cancel each other and electromagnetic energy is redirected to non-specular directions, resulting in significant RCS reduction. To gain the phase conditions for scattering cancellation and high-efficiency transmission, full-wave electromagnetic simulations are carried out to design the structural parameters, including FSS patterns, layer thicknesses and unit dimensions. A prototype sample is fabricated via printed circuit board processing, vacuum-assisted resin infusion and low-dielectric adhesive bonding. Free-space measurement in a microwave anechoic chamber shows that the proposed radome achieves over 10 dB RCS reduction in 4-8 GHz and 12-18 GHz under normal incidence, and the insertion loss is less than 1 dB within frequency range of 8-12 GHz. The simulated and measured results are highly consistent, verifying the effectiveness and repeatability of the design. Compared with traditional absorbing radomes, this structure features planar configuration, loss-free mechanism, simple preparation, low cost and stable electromagnetic performance, providing a new feasible scheme for high-performance stealth radome design. It is believed that this work may find potential engineering application for the low-observable design in shipborne, airborne and vehicular antenna systems.

     

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