Search

The continuous increase in communication capacity is accompanied by an increase in transmission frequency, which creates new demands on the transmission efficiency in modern. Signal relay transmission can increase the transmission distance, however, conventional repeaters relay the signal in a specified direction, which is difficult to accommodate communication when a receiving device suddenly appears around the repeater. In this work, we propose a new signal transmission repeater, which is implemented by an adaptively reconfigurable multi-beam reflective metasurface based on multispectral detection. The reconfigurable metasurface with varactor diodes is designed and the mapping of phase profiles to voltages is established by polynomial fitting method. Visual, laser, infrared and ultrasonic detectors are used to detect targets in different scenarios. Thus, the detection information is fed back to the reconfigurable metasurface for adaptively multi-beam switching. As verification, the adaptive metasurface repeater was fabricated and measured to verify our design. All the results exhibit consistency with theoretical design. Importantly, this work paves a new way to intelligent metasurfaces and may find applications in intelligent communications, smart home, etc.

The traditional demand split logistics distribution schemes are mainly based on vehicle distribution. In recent years, with the rapid development of civil UAVs, the use of UAVs for distribution will be more efficient and economical in some specific conditions. In this paper, through the analysis of the advantages of UAV distribution, we simulate the demands and distribution schemes in real scene, especially in remote mountainous areas. And then, we propose to define a demand-splitting distribution scheme of vehicle-supported UAV, which ensures the customer point will be satisfy demand when the loading capacity of the UAV is exceeded. This scheme aims to provides a realizable distribution scheme for the customers point in mountainous areas with large demand.

The back-scattering from front edge diffraction contributes significantly to mono-static radar cross section under TE-polarization when the specular reflection of an object is eliminated by elaborate shaping. With the aim to suppress the back-scattering of thin metallic edge, we propose to achieve wideband radar cross section (RCS) reduction by integrating an absorbing structure (AS) in front of the edge. The unit cell of AS is composed of a longitudinal array of metallic strips with linearly decreasing lengths. Under TE-polarized illumination, spoof surface plasmon polariton (SSPP) can be excited with high efficiency. Due to the deep-subwavelength property of SSPP, electromagnetic waves are highly confined around the AS, leading to strong local field enhancement and hence to wideband absorption. In this way, back-scattering of the edge is suppressed and the mono-static RCS can be reduced significantly over wide band. To verify this method, we designed, fabricated and measured a prototype. The results of both simulation and measurement indicate that our proposal can significantly suppress edge scattering, whose RCS reduction more than 10 dB achieves at range of 8.8–17.8 GHz under TE polarization. This work provides a new alternative of suppressing edge diffraction and may find applications in electromagnetic compatibility, radar stealth, etc.

Geometric phases are very important for achieving broadband functional metasurfaces, which are usually obtained by rotating meta‐atoms. However, such rotation‐induced geometric phases are inherently spin‐coupled, with the same magnitude and opposite sign for left‐ and right‐handed circularly polarized (LCP and RCP) waves, which is unfavorable for designing different functions for LCP and RCP waves. Therefore, it is desirable that geometric phases for single circular polarization be explored. In this work, it is first proposed to achieve geometric phases for single polarization by delicately designing curvature of the meta‐atom, which only imparts geometric phase to RCP or LCP waves. Then, spin‐decoupled metasurfaces are designed by hybridizing such curvature‐induced geometric phases and conventional rotation‐induced geometric phases. Two prototypes of dual‐channel functional metasurfaces are designed, fabricated, and measured. Both the simulated and experimental results verify the spin‐decoupled phase modulation. This work expands the methods of phase engineering in metasurfaces and may find wide applications in communication, sensing, imaging, and others. [ABSTRACT FROM AUTHOR]

All-angle wideband electromagnetic (EM) transparency for dual polarizations is desired for many practical applications. Conventionally, surface-mount anti-reflection materials or films are usually used to reduce the reflection and thus enhance transparency. In this paper, we propose to achieve wideband EM transparency under extreme angles for both TE- and TM-polarizations using embedded anti-reflection metasurface. The metasurface is composed of a pair of long and short metallic strips, which can introduce both plasma and lattice modes into the original half-wave wall. The plasma mode can create an angle-stable transmission peak at a lower frequency while the lattice mode renders a transmission peak under extreme angles at a higher frequency due to scattering cancellation between short strips and the substrate. By synergizing the plasma, half-wave, and lattice modes consecutively, wide-band transparency can be achieved under extreme angles for TE polarization. Due to the anisotropy of the metasurface, wideband transparency under TM-polarization is maintained. This finally enables us to obtain wideband EM transparency for dual polarizations under extreme angles. More importantly, the metasurface can also be customized to operate best under any given incident angle. Prototypes were designed, fabricated, and measured. Both the simulation and experiment results verify our method. This work provides an efficient route to wideband EM transparency under extreme angles and may find wide applications in communication, radar, and others. [ABSTRACT FROM AUTHOR]

Metasurfaces composed of subwavelength structure arrays provide a diverse and powerful platform for generation of complicated electromagnetic (EM) fields and wavefronts manipulation and have triggered an unprecedented research upsurge in electromagnetism with the development of computer‐generated holography (CGH). Different from conventional scalar holograms only containing amplitude and phase properties, a vectorial hologram that benefits from the maneuverability of polarization of EM fields exhibits more immeasurable application potential and is simultaneously regarded as an urgent requirement. In this work, assisted by single completely spin‐decoupled meta‐particles, which perfectly combine the functions of simultaneous and independent amplitude and phase modulation of orthogonal polarization states containing left‐ and right‐handed circularly polarized (LCP&RCP) components, a vectorial hologram induced through eigenstates degeneracy with the ability of encoding arbitrary polarization is proposed in the microwave region. As the proof of concept, eight distinct holograms with specified polarizations and six‐channel polarization‐multiplexed hologram display are fabricated and characterized, further showcaing the versatility of the approach for the customization of arbitraty polarization and integration of reconstructed patterns. With the advantages of multi‐controllability and ultra‐compactness, the constructed monolayer completely spin‐decoupled paradigm for vectorial regulation may find prospective application aspects in spin detection, target perception, multi‐channel data encryption, and many other related fields. [ABSTRACT FROM AUTHOR]

Controlling objects with body language is an extremely interesting ability for human beings. Recognizing different gestures is an effective way to collect valuable information, which is used to switch the radiation characteristic of beam scanning antennas. However, most existing beam scanning antennas are wire-connected and manually controlled by users. Thereby, a novel framework of gesture-controlled antennas is proposed in this paper. Rather than DC voltages supplied by powers or AC voltages supplied by signal generators, the beam scanning antenna can be effectively controlled by different gesture commands collected in real time from the user. On this basis, considering the advantages of the low cost and wide frequency band of liquid crystal (LC) materials, a LC-based fixed-frequency beam scanning leaky wave antenna (LWA) with gesture-controlled systems is demonstrated as one example. Different gestures can be recognised as controlled information to supply corresponding output signals by field programmable gate arrays (FPGAs) for the LC-based LWA. Based on the proposed framework, a verification system is tested, which demonstrates that the radiation characteristic can be effectively controlled by the user's gesture. This work supplies a novel way for intelligent beam scanning antennas with potential applications in the internet of things (IoT), satellite and 5 G/6 G communications. [ABSTRACT FROM AUTHOR]