3D absorptive frequency-selective reflection and transmission structures with dual absorption bands

• Main Authors: Yu, Yufeng, Luo, Guo Qing, Ahmed Abdelmottaleb Omar, Liu, Xuan, Yu, Weiliang, Hao, Zhang Cheng, Shen, Zhongxiang
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: Absorptive Frequency-selective Reflector; Absorptive Frequency-selective Transmission Structure
• Online Access: https://hdl.handle.net/10356/103394; http://hdl.handle.net/10220/47287
• Institution: Nanyang Technological University

This paper presents a 3D absorptive frequency-selective reflection structure (AFSR) and absorptive frequency-selective transmission structure (AFST) with one reflection/transmission band and two absorption bands. The 3D AFSR utilizes the intrinsic reflection band and higher order absorption band of a wideband 3D absorber. By simply loading a printed gap capacitor in the structure, the reflection band can be easily tuned by varying the capacitance of the capacitor. A design example is presented, with a reflection band of 24.7% fractional bandwidth (FBW), a lower absorption band of 72.5% FBW, and a higher absorption band of 48.6% FBW. A 3D AFST composed of the 3D AFSR and a parallel-plate waveguide is then proposed. Its general operating principle is demonstrated, such that the 3D AFST can be seen as a combination of a 3D AFSR and a 3D band-pass FSS, which can independently contribute to the absorption and transmission, respectively. A set of guidelines is proposed to facilitate the design. A prototype of the proposed AFST is fabricated and measured. The measured results show that the transmission band is with a minimum insertion loss of 0.4 dB and an FBW of 30%. Moreover, the lower and higher absorption bands are with 63.9 % and 47.6 % FBW, respectively. The proposed AFST has a simpler structure, wider lower absorption bandwidth, and thinner thickness compared with previous structures.