Theoretical research on an ultra-wideband Janus metastructure for bidirectional electromagnetic wave absorbing

In this article, a bidirectional ultra-wideband wave-absorbing metastructure (WAMS) with Janus properties is proposed. The symmetrical propagation of EM waves is broken by the asymmetric arrangement of cross-shaped split ring resonators of different sizes. The results unequivocally demonstrate that when the EM wave is incident in the +z-direction, the WAMS exhibits more than 90% absorption in the ranges of 0.86–1.21 THz and 1.58–1.76 THz. The relative bandwidths (RB) are 33.8% and 10%, respectively. When the EM wave is incident in the −z-direction, the absorption band is 1.33–1.76 THz, and the RB reaches 27.8%. An equivalent circuit model is utilized to elucidate the underlying physical mechanism of this WAMS based on a study of the equivalent circuit model of conventional split ring resonators. Due to the WAMS's high symmetry in the x–y plane, it is insensitive to the polarization state of the EM waves. Additionally, the WAMS has remarkable angular stability across a spectrum of incidence angles from 0 to 55° when directed in the +z-direction, and from 0 to 45° when directed in the −z-direction. The given WAMS provides a new idea for the design of bidirectional ultra-wideband Janus absorbers, and has a broad application prospect across various fields such as radar asymmetric stealth, multiplexed systems, beam splitters, and full-space EM wave control.