Miniaturized Periodicity Broadband Absorber With Via-Based Hybrid Metal-Graphene Structure for Large-Angle RCS Reduction

Abstract

In this article, we present a via-based hybrid metal–graphene metamaterial absorber with miniaturized periodicity, broad absorption band, and large-angle radar cross Section (RCS) reduction. The unit cell of the absorber is composed of a cross-shaped graphene film, four metal arrow-shaped patterns, and four cylindrical vias. By extending the length of vias and folding the shape of the pattern on the top, the unit size of this proposed absorber is reduced greatly, while its absorption performance maintains. Furthermore, the adopted hybrid metal–graphene structure avoids loading multiple lumped elements, and the complexity and the cost of the fabrication are reduced by screen-printing technology. Because of the elements with miniaturized periodicity, the proposed absorber can shift the grating lobe (GL) out of the absorption band when illuminated by a large-angle oblique incident wave. A prototype absorber is fabricated and measured. The period of the proposed absorber is about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.045\lambda _{L}$ </tex-math></inline-formula> at the lowest operating frequency. To the best of our knowledge, it is the smallest among the reported counterparts. Experimental results show that the absorber exhibits broadband absorption around 2.73~7.54 GHz and efficient RCS reduction with no GL under a large incident angle. The equivalent circuit analysis, full-wave simulation, and measurement results are in good agreement.