This article presents an ultrathin single-layer broadband microwave absorber operating at the frequency band of 22.6–33 GHz with a fractional bandwidth of 37.4%. The absorber is designed on a low-temperature co-fired ceramic substrate using ruthenium oxide (RuO ₂ ) at the top and silver at the bottom of the substrate. The overall thickness of the absorber is 1.02 mm, i.e., 0.076 λ _L , where λ _L is the free space wavelength at the frequency of 22.6 GHz. The absorber is polarization-insensitive to the incident EM wave due to its fourfold symmetrical structure, and it absorbs more than 90% of the incident EM wave for oblique incidence up to ± 40°. In comparison to a same-sized metal sheet, the radar cross-section reduction obtained by the proposed absorber is more than 10 dB throughout the entire operating frequency band and the reduction reaches 32 dB at the frequency of 29 GHz. The absorber shows good absorption stability with the variation of ambient temperature and humidity. This absorber can be instrumental for electromagnetic interference shielding and stealth technology.

中文翻译：

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在单层 LTCC 基板上使用氧化钌的偏振和入射角独立宽带微波吸收器

本文介绍了一种超薄单层宽带微波吸收体，工作频率为 22.6–33 GHz，分数带宽为 37.4%。该吸收器设计在低温共烧陶瓷基板上，顶部使用氧化钌（RuO ₂ ），底部使用银。吸波体整体厚度为1.02毫米，即0.076 λ _L ，其中λ _L是频率为 22.6 GHz 的自由空间波长。由于其四重对称结构，吸收体对入射电磁波偏振不敏感，并且对于±40°的倾斜入射，它可以吸收90%以上的入射电磁波。与相同尺寸的金属板相比，所提出的吸波器在整个工作频带内获得的雷达截面减少超过10 dB，并且在29 GHz频率下减少达到32 dB。该吸收体随着环境温度和湿度的变化表现出良好的吸收稳定性。这种吸收器可有助于电磁干扰屏蔽和隐形技术。