In this study, we present a novel ultra-wideband passive polarization conversion metasurface (PCM) that integrates double V-shaped patterns with circular split-ring resonators. Operating without any external power supply or active components, this design effectively manipulates the polarization state of incident electromagnetic waves. Numerical and experimental results demonstrate that the proposed PCM can convert incident linear polarization into orthogonal states across a wide frequency range of 7.1–22.3 GHz, encompassing the C-, X-, Ku-, and K-bands. A fabricated prototype confirms that the polarization conversion ratio (PCR) exceeds 90% throughout the specified band. Furthermore, we explore an additional application of this passive metasurface for electromagnetic stealth, wherein it achieves over 10 dB of monostatic radar cross-section (RCS) reduction from 7.6 to 21.5 GHz. This broad effectiveness is attributed to strong electromagnetic resonances between the top and bottom layers, as well as the Fabry–Pérot cavity effect, as evidenced by detailed analyses of the underlying physical mechanisms and induced surface currents. These findings confirm the effectiveness of the proposed design and highlight its potential for future technological applications, including 6G communications, radar imaging, anti-interference measures, and electromagnetic stealth.

This paper presents a novel Double-negative (DNG) metamaterial (MM) resonator with a mirror-symmetric configuration, designed to exhibit multiband resonances in the S, C, and X bands. The resonator is fabricated using advanced processing techniques on a Rogers 5880 substrate and features electrodeposited copper. It consists of four equal regions, each containing interconnected split-ring resonators that are connected through a cross-shaped structure to ensure mirror symmetry. The simulation results demonstrate six resonance points at frequencies of 2.45 GHz, 4.27 GHz, 6.86 GHz, 8.98 GHz, 10.69 GHz, and 11.65 GHz. These resonances are characterized by near-zero/negative permeability, negative permittivity, refractive index, and impedance. Furthermore, the cross-polarization effect of incident waves is investigated.

Metamaterial absorbers have gained widespread applications in fields such as sensing, imaging, and electromagnetic cloaking due to their unique absorption characteristics. This paper presents the design and fabrication of a novel K-band polarization-sensitive metamaterial absorber, which operates in the frequency range of 20.76 to 24.20 GHz for both TE and TM modes, achieving an absorption rate exceeding 90% and a bandwidth of up to 3.44 GHz. The structure of the metamaterial absorber consists of a rectangular aperture metallic patch, two metallic rings, and two metallic strips, with a metallic patch structure on the back. Both metallic patches are printed on a 1.575 mm-thick FR-4 substrate. In the TE mode, the performance shows diagonal symmetry, with a minimum absorption bandwidth of 1.4 GHz at 45° and a maximum of 3.44 GHz at 0°. The absorption rate exceeds 90% across various polarization angles. In terms of conventional modes, both the TE and TM modes can achieve ultra-wideband absorption. For specific scenarios requiring single-frequency or multi-frequency absorption, the desired functionality can be realized by varying the incident angle. These exceptional characteristics confer strong applicability for high-bandwidth electromagnetic wave absorption and specific frequency point absorption, indicating significant potential and practical value in the field of wireless communication.

Metamaterial absorbers have widespread applications in fields such as communication, electromagnetic stealth, and electromagnetic interference due to their unique electromagnetic properties. This paper propose a flexible metamaterial absorber with indium tin oxide as the resonant element and PTFE as the substrate material. The absorber exhibits an absorption rate exceeding 90% across the frequency range of 11.65–75 GHz, with a maximum absorption bandwidth of 63.35 GHz, covering the Ku, K, Ka, U, and V bands. The structure is insensitive to polarization angles in the range of 0°–90° for both TE and TM modes, demonstrating excellent absorption stability for both modes. The flexible structure has a thickness of 1.51 mm, and its curvature adaptability allows it to effectively absorb electromagnetic waves even at different bending angles. Therefore, these exceptional characteristics make the absorber highly valuable and promising for practical applications in wireless communication, 5G high-frequency communication, radar stealth, and satellite stealth.

Energy bandgap opening has been found in low-buckle bilayer silicene under tensile in-plane strain. Practically such substantial in-plane strain could be provided from the substrates. The intense interfacial covalent bonds ensure an in-plane lattice-matching expitaxial growth, but at the same time impose a challenge in forming low-buckle two-dimensional films. We performed a theoretical study using density function theory to investigate the feasibility of growing bilayer silicon under excessive in-plane strain on various substrates. By the insertion of an air gap, dative bonds have been found at the interface on the substrates with the preferred polarized surface. The interactions of the transferred electrons from the surface-terminating metallic atoms of the substrates and the electron sea in the bilayer silicon was observed. The strength of the dative bond is reduced to about ∼0.05% of the Ga–Si covalent bond in the absence of the air gap. Preservation of substantial in-plane strain has been obtained in the bilayer silicon, resulting in a low-buckle bilayer silicon with opened energy bandgap up to ∼75 meV.

This paper presents an innovative programmable metasurface structure that achieves precise phase control within the 2–2.7 GHz frequency range by adjusting the state of varactor diodes embedded in the unit cells. The design employs a single diode, which simplifies the structure, reduces manufacturing costs, and minimizes reflection loss. At 2.4 GHz, the metasurface achieves 1-bit phase responses of 0° and 180°, with a reflection amplitude exceeding 0.72, demonstrating excellent reflective performance. Moreover, as the 2.4 GHz frequency is closely related to wireless communication bands, this programmable metasurface shows significant potential in the field of wireless communication encryption. By integrating dual varactor diodes, the design enables 2-bit phase control with reflection phase angles of 0°, 90°, 180°, and 270°. To validate the design, a 1-bit metasurface structure was fabricated and tested, with experimental results showing a high degree of consistency with simulations, highlighting the potential of this structure in enhancing wireless communication security.