In this article, a closed ring resonator-based absorber with eleven consecutive absorption peaks is proposed over X and K bands with an average absorption rate of 96.29%. The proposed design consists of circular ring resonators embedded in the circularly slotted square patch printed on the top of the grounded FR-4 substrate. The surface current distributions well illustrates the reason behind the electromagnetic (EM) wave absorption. The design is polarization insensitive for normal incidence and wide angular stable up to 45° for TE (60° for TM) polarization. The structure is fabricated on a single-layered FR-4 dielectric substrate with a periodicity of ${{\boldsymbol{\lambda }}_{\boldsymbol{o}}}$ /2.32 and thickness of ${{\boldsymbol{\lambda }}_{\boldsymbol{o}}}$ /16.74, where ${{\boldsymbol{\lambda }}_{\boldsymbol{o}}}$ is the free-space wavelength at the lowest resonant frequency. A transmission line-based equivalent circuit model has been illustrated and good agreement is observed with full-wave simulations. This article's novelty lies in the absorption mechanism of eleven consecutive absorption peaks, demonstrating the controllability of the absorptivity peaks and resonant frequency. To the best of the authors’ knowledge, the proposed absorber demonstrates the highest number of near-unity successive absorption bands with better angular stability. The proposed structure was checked for radar cross section reduction application with an X -band antenna and results show 19.7-dBsm reduction at normal incidence.

中文翻译：

---

一种用于 EMI/EMC 应用的简单偏振不敏感且宽角稳定圆环十一波段吸收器


在本文中，提出了一种基于闭环谐振器的吸收器，在 X 和 K 波段具有 11 个连续吸收峰，平均吸收率为 96.29%。所提出的设计由嵌入在接地 FR-4 基板顶部印刷的圆形开槽方形贴片中的圆环谐振器组成。表面电流分布很好地说明了电磁（EM）波吸收背后的原因。该设计对于法向入射偏振不敏感，对于 TE（TM 偏振为 60°）广角稳定达 45°。该结构在单层 FR-4 介电基板上制造，周期为 ${{\boldsymbol{\lambda }}_{\boldsymbol{o}}}$ /2.32，厚度为 ${{\boldsymbol{\ lambda }}_{\boldsymbol{o}}}$ /16.74，其中 ${{\boldsymbol{\lambda }}_{\boldsymbol{o}}}$ 是最低谐振频率下的自由空间波长。已经说明了基于传输线的等效电路模型，并且与全波仿真观察到良好的一致性。本文的新颖之处在于11个连续吸收峰的吸收机制，证明了吸收率峰和谐振频率的可控性。据作者所知，所提出的吸收器表现出最多数量的接近一致的连续吸收带，并且具有更好的角度稳定性。所提出的结构通过 X 波段天线的雷达截面减小应用进行了检查，结果显示法向入射时减小了 19.7 dBsm。