This paper presents the design and analysis of a low-pass spatial filter which has wideband absorption at high frequency using a 3D metamaterial rasorber (MR). The unit cell of the 3D MR is composed of several stacked layers of square patches with tapered dimensions, which are separated by thin lossy dielectric laminas. Every two adjacent layers’ metallic patches constitute a resonance cavity, and the inside lossy dielectric substrate results in absorption at the resonance frequency. The stacked metal–dielectric laminas construct a frustum pyramid. With the dimensions of the resonance cavities tapering from the bottom layer to the top layer, the pyramid absorbs over their resonance frequencies so that wideband absorption can be achieved. Besides, the incident wave at the frequencies below all these resonance frequencies can transmit through these cavities. Hence, the pyramid also constructs a low-pass spatial filter. The operation mechanism of this 3D MR structure is analyzed from several aspects by numerical simulation, and experimental measurement has also been executed to verify the design. The 3D metamaterial rasorber performs as an absorber in the Ku-band and a low-pass filter below the X-band. The absorption band with absorptivity higher than 80% spans from 12.3 GHz to 18.2 GHz, and the insertion loss at the frequency below 11.1 GHz is less than 0.9 dB.

中文翻译：

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基于3D异质材料吸收体的高频低通低通滤波器

本文介绍了一种低通空间滤波器的设计和分析，该滤波器使用3D超材料吸收器（MR）在高频下具有宽带吸收能力。3D MR的晶胞由具有锥形尺寸的多层方形贴片的多层堆叠构成，并由薄的有损介电薄片隔开。每两个相邻层的金属贴片构成一个谐振腔，内部有损耗的电介质衬底导致在谐振频率下吸收。堆叠的金属-电介质薄片构成一个平截头锥体。随着谐振腔的尺寸从底层到顶层逐渐变细，金字塔在它们的谐振频率上吸收，从而可以实现宽带吸收。除了，低于所有这些谐振频率的频率的入射波可以通过这些腔传播。因此，金字塔还构造了一个低通空间滤波器。通过数值模拟从多个方面分析了这种3D MR结构的运行机理，并进行了实验测量以验证设计。3D超材料吸收器在Ku波段中充当吸收器，在X波段下充当低通滤波器。吸收率高于80％的吸收带的范围从12.3 GHz到18.2 GHz，并且在11.1 GHz以下的频率下的插入损耗小于0.9 dB。并且还进行了实验测量以验证设计。3D超材料吸收器在Ku波段中充当吸收器，在X波段下充当低通滤波器。吸收率高于80％的吸收带的范围从12.3 GHz到18.2 GHz，并且在11.1 GHz以下的频率下的插入损耗小于0.9 dB。并且还进行了实验测量以验证设计。3D超材料吸收器在Ku波段中充当吸收器，在X波段下充当低通滤波器。吸收率高于80％的吸收带的范围从12.3 GHz到18.2 GHz，并且在11.1 GHz以下的频率下的插入损耗小于0.9 dB。