High-Efficiency Transmissive Programmable Metasurface for Multimode OAM Generation

The recently proposed digital reconfigurable metasurfaces make it possible to manipulate electromagnetic (EM) waves flexibly. However, most existing reconfigurable metasurfaces can only exhibit a relatively single performance in the spatial domain. Here, we propose a general frequency- and spatial-domain reconfigurable metasurface (FSRM) that can manipulate the EM waves and realize reconfigurable functions in multifrequency bands. In the frequency domain, FSRM can convert different linearly polarized (LP) incident waves into left- and right-hand circularly polarized reflected waves, in which PIN diodes are used to switch the polarization conversions in different frequency bands. When the polarization direction of the incident LP wave is 45° from the +x-axis, the FSRM modulates the incident waves as a 1-bit programmable metasurface in the spatial domain. Two-dimensional beam scanning, vortex beams with orbital angular momentums, and specific beams with desired transmission directions are demonstrated via real-time adjustment of the digital coding state. To validate the modulation methodology, an FSRM prototype is fabricated and measured, which could respond to different functions for different polarization incidences. The measured results agree well with the theoretical analyses. The proposed FSRM will provide new opportunities for smart material designs.

Frequency-Domain and Spatial-Domain Reconfigurable Metasurface.

Reconfigurable metasurfaces have emerged as a versatile platform for reshaping the wireless environment into a desirable form at low cost. Despite the rapid growth, most of the existing metasurfaces only support reflection operation or transmission operation, only providing service coverage of backward or forward half-space when they are used for wireless communications. Here, an intelligent programmable omni-metasurface integrating reflection mode, transmission mode, and duplex mode of simultaneous reflection and transmission modes in the same polarization and frequency channel is proposed, capable of providing ubiquitous full-space service coverage for multiuser wireless communication applications. As exemplary demonstrations, a series of dynamic functionalities have been realized, including twin-beam scanning in reflection mode, twin-beam scanning in transmission mode, and identical/distinct dynamic beams for both forward and backward half-spaces in duplex mode, which are customized for signal reflection, transmission, and simultaneous symmetric/asymmetric reflection and transmission in wireless communication scenarios. The proposed tunable omni-metasurface provides a new method for full-space wave manipulation, which may offer untapped potentials for real-time, fast, and sophisticated wave control in applications such as miniaturized systems, integrated photonics, and intelligent communications. 

An Intelligent Programmable Omni‐Metasurface

This article presents an active cylindrical metasurface with spatial reconfigurability to achieve dynamic control of the radar cross section (RCS) reduction. The proposed metasurface is designed based on the combination of microwave transmission network and Mie scattering. In particular, by modulating the spatial coding sequence of p-i-n diodes in meta-atoms, the surface impedance of the metasurface can be dynamically changed, which enables an active metasurface to operate in an expanded frequency band via time-division multiplexing technique. Both simulated and measured results demonstrate that the proposed cylindrical metasurface with an ultrathin thickness of $0.018\lambda $ can be continuously tuned across a wide fractional bandwidth over 32% for reducing backward scattering by 10 dB. The proposed metasurface with ultrathin thickness, tunability, conformal profile, and high performance may be applied to wideband RCS reduction, as well as advanced noninvasive detection, communication, etc.

Active Cylindrical Metasurface With Spatial Reconfigurability for Tunable Backward Scattering Reduction

Abstract In the last two decades, metamaterials and metasurfaces have introduced many new electromagnetic (EM) theory concepts and inspired contemporary design methodologies for EM devices and systems. This review focuses on the recent advances in metamaterials (MMs) for simultaneous wireless information and power transmission (SWIPT) technology. In the increasingly complex EM world, digital coding and programmable metamaterials and metasurfaces have enabled commercial opportunities with a broad impact on wireless communications and wireless power transfer. In this review, we first introduce the potential technologies for SWIPT. Then, it is followed by a comprehensive survey of various research efforts on metamaterial-based wireless information transmission (WIT), wireless power transmission (WPT), wireless energy harvesting (WEH) and SWIPT technologies. Finally, it is concluded with perspectives on the rapidly growing SWIPT requirement for 6G. This review is expected to provide researchers with insights into the trend and applications of metamaterial-based SWIPT technologies to stimulate future research in this emerging domain.

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Recent advances in metamaterials for simultaneous wireless information and power transmission

Active metasurfaces pave a way for manipulating electromagnetic (EM) waves in real-time by incorporating with tunable materials or components, emerging as an attractive solution to achieve versatile EM functionalities in dynamic fashions. However, most of the active metasurfaces demonstrated so far only support tunable responses for a certain single frequency band, or have obvious frequency cross-talks that cannot provide dual-band independent operations, limiting their further uses in practical applications. Here, we propose a 1-bit high-efficiency programmable metasurface to achieve completely independent functions with real-time reconfigurability controlled by FPGA hardware system in both C-band and X-band. Specifically, the metasurface is designed with abilities of generating multi-beams or twin-beam scanning in the low frequency band while dynamic beam-scanning in high frequency band. As the experimental verifications, a double-layered metasurface has been fabricated and tested, and the measured results agree well with the simulations, demonstrating its abilities of independent, high-efficiency, real-time, and programmable manipulation of EM waves in two discrete frequency bands. The proposed concept may largely enhance the information capacity of the metasurface, bringing new degrees of freedom in achieving versatile tunable functionalities and offering useful applications in the radar and wireless communication systems.

Jian Wang

Papers

Programmable Coding Metasurface for Dual-Band Independent Real-Time Beam Control