Flexible design and realization of wideband microwave absorber with double-layered resistor loaded FSS

Abstract

A flexible design of a wideband double-layer microwave absorber is proposed. In order to break through the limitation of single-layer absorbers at finite resonant frequencies, a special double-layered structure is adopted. The middle layer functional frequency selective surface is the core of the double-layer absorber. It exhibits two functions, which are resonant or lossy in a low frequency and strong reflective in a high frequency. As a result, the coupling between the two layers is weak, and this feature leads to the absorber having two different absorption bands which are provided by two single-layer absorbers (named as functional layers (FLs)), respectively. It means that an engineer could target the design for a particular band according to requirements without degrading the performance on the other band. For the flexible design, two FLs, a dual-band absorption precursor and a continuous absorption modified absorber are proposed successively. During the whole design process, all structures are fabricated and measured. The measurement result shows that the reflection of the modified absorber below −10 dB covers a bandwidth of 2.98-16.62 GHz in normal incidence. The good agreement between simulation and measurement validates the proposed absorber.

Design of an ultra‐broadband microwave metamaterial absorber based on multilayer structures

“…Many multilayer units have been proposed to achieve wideband absorption or radar cross‐section (RCS) reduction 14–26 . An ordinary design idea is to combine multiple single‐band (SB) absorbers operating in different frequencies using a multi‐layer structure and ultimately achieve absorption in the broadband range.…”

“…A double‐layer metal square loop integrated with resistors is designed, which has a reflectivity below −10 dB from 1.92 to 16.87 GHz 18 . Several other CAAs not only maintain a wide absorption bandwidth but also achieve some other characteristics, that is, flexible, conformal, optically transparent, and so on 19–21 . Therefore, the multilayer structure is a popular method to improve the wideband performance of the absorber, which is also applied in the optical range, THz, and mid‐infrared range 22–24 …”

“…12,13 Many multilayer units have been proposed to achieve wideband absorption or radar cross-section (RCS) reduction. [14][15][16][17][18][19][20][21][22][23][24][25][26] An ordinary design idea is to combine multiple single-band (SB) absorbers operating in different frequencies using a multi-layer structure and ultimately achieve absorption in the broadband range. A pyramid absorber consisting of 10 layers of SB absorber structures is proposed, 14 which achieves a high absorption rate (>90%) in X-band and Ku-band with a fractional bandwidth of 71% and the total thickness is 0.26 λ L at the lowest operating frequency.…”

“…18 Several other CAAs not only maintain a wide absorption bandwidth but also achieve some other characteristics, that is, flexible, conformal, optically transparent, and so on. [19][20][21] Therefore, the multilayer structure is a popular method to improve the wideband performance of the absorber, which is also applied in the optical range, THz, and mid-infrared range. [22][23][24] In our work, an ultra-broadband double-layer MMA with five resonances was proposed.…”

Highly Transparent Broadband and Polarization-Insensitive Absorber Based on Metasurface

“…This absorption property has developed from the polarization sensitivity and normal incidence to polarization-insensitive and wide incidence angle stability [16,17]. The absorption bands have gradually extended from the initial radio frequency and microwave bands [18,19] to terahertz [20][21][22], infrared [23][24][25] and even visible bands [26,27]. Among them, optically transparent metamaterial absorbers have attracted a lot of attention because of their significant and extensive potential applications [28][29][30], such as radio frequency identification systems [31][32][33], electronic toll collection (ETC) systems [34], observation windows in stealth aircraft and electromagnetic shielding of rooms [35].…”