This article presents designs of 3-D microwave absorbers with synthesizable absorptive performance. The synthetic procedure is investigated based on the unified equivalent transmission line (TL) model, which theoretically supports different performances. According to the desired absorptive performance, including the normalized absorptive resistance (NAR) and fractional bandwidth (FBW), the impedance parameters in the equivalent model can be easily obtained from the closed-form calculation. For demonstration, two prototypes are structurally developed and their different absorptive performances are measured. Each prototype element is designed with a single-layered 3-D structure consisting of composite TLs and only one loaded resistor. The measurements are in close agreement with the synthesized and simulated results, demonstrating an FBW of 99.0% (from 4.95 to 14.66 GHz) for absorber-A with a smaller NAR of 0.53. Absorber-B with a larger NAR of 1.25 obtains a measured FBW of 84.3% (from 5.76 to 14.16 GHz). These two absorbers realize in-band absorption ratios of 92.4% and 93.0% on average. In addition, efficient absorption can be obtained within 45° oblique incidence. Therefore, such a type of the proposed 3-D microwave absorber with synthesizable absorptive performance is indeed a promising candidate to customize electromagnetic wave absorption.

中文翻译：

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具有可合成吸收性能的 3-D 微波吸收体的设计

本文介绍了具有可合成吸收性能的 3D 微波吸收器的设计。基于统一的等效传输线（TL）模型研究了合成过程，该模型理论上支持不同的性能。根据所需的吸收性能，包括归一化吸收电阻（NAR）和分数带宽（FBW），可以通过闭式计算轻松获得等效模型中的阻抗参数。为了进行演示，我们在结构上开发了两个原型，并测量了它们不同的吸收性能。每个原型元件均采用单层 3D 结构设计，由复合 TL 和仅一个负载电阻组成。测量结果与合成和仿真结果非常一致，表明吸收体 A 的 FBW 为 99.0%（从 4.95 到 14.66 GHz），且 NAR 较小为 0.53。具有较大 NAR 1.25 的吸收器 B 获得的测量 FBW 为 84.3%（从 5.76 到 14.16 GHz）。这两种吸收器的带内吸收率平均为 92.4% 和 93.0%。此外，在45°斜入射范围内可以获得高效吸收。因此，这种具有可合成吸收性能的3D微波吸收体确实是定制电磁波吸收的有希望的候选者。