A broadband low-profile high-gain folded transmitarray antenna (FTA) is proposed to generate orbital angular momentum (OAM) with circular polarization. A chiral metasurface is employed as the top layer with the function of reflecting anticipant circularly polarized (CP) incident waves while transmitting the orthogonal ones. The geometric phase is then introduced to achieve 360° coverage of the transmission phase without affecting the reflection one. To obtain a high-gain and compact planar source, a 2 × 2 patch antenna array, integrated with the bottom metallic ground, is selected as the feed. Two proof-of-concept prototypes for vortex beam generation are constructed and experimentally measured. Both simulated and measured results demonstrate that l =–1 and l =+1 OAM mode beams can be generated from 8.7 GHz to 9.5 GHz, and the measured maximum gains for l =–1 and l =+1 reach 18.1 dBi and 18.3 dBi with the corresponding peak aperture efficiencies of 6.1% and 6.4%, respectively. Meanwhile, the axial ratios (ARs) of the peak of far-field patterns are less than 3 dB over the entire operating frequency range, providing broadband CP vortex beams. The proposed high-gain low-profile broadband FTA antenna shows a promising perspective in OAM-based wireless communication.

Diodelike spin-orbit interactions of light at metasurfaces bring novel functionalities to optical devices but have never been achieved so far. In this paper, we experimentally demonstrate a diodelike asymmetric metadevice that exhibits asymmetric spin-orbit interactions of light in chiral metasurfaces. The exploited physical mechanism is based on the maximization of the polarization conversion for a designated circularly polarized light in transmission. Chiral meta-atoms are employed to enhance the interaction between spin angular momentum and matter, while phase discontinuities are introduced at the interface for helicitydependent generation of orbital angular momentum. Three proofof- concept metasurfaces that demonstrate asymmetric circular polarization conversion, asymmetric spin deflection and asymmetric spin-to-vortex conversion are designed, fabricated, and experimentally characterized, respectively. Compared with the Faraday effect under the external magnetic field, the designer metasurfaces here are all reciprocal and offering asymmetric angular momentum division with high efficiency. Our findings provide the possibility of asymmetric multifunctional metadevices for high-performance on-chip parallel multiplexing.

The flexible and conformal interconnects for electronic systems as a potential signal transmission device have great prospects in body-worn or wearable applications. High-efficiency wave propagation and conformal structure deformation around human body at radio communication are still confronted with huge challenges due to the lack of methods to control the wave propagation and achieve the deformable structure simultaneously. Here, inspired by the kirigami technology, a new paradigm to construct spoof plasmonic interconnects (SPIs) that support radiofrequency (RF) surface plasmonic transmission is proposed, together with high elasticity, strong robustness, and multifunction performance. Leveraging the strong field-confinement characteristic of spoof surface plasmons polaritons, the Type-I SPI opens its high-efficiency transmission band after stretching from a simply connected metallic surface. Meanwhile, the broadband transmission of the kirigami-based SPI exhibits strong robustness and excellent stability undergoing complex deformations, i.e., bending, twisting, and stretching. In addition, the prepared Type-II SPI consisting of 2 different subunit cells can achieve band-stop transmission characteristics, with its center frequency dynamically tunable by stretching the buckled structure. Experimental measurements verify the on-off switching performance in kirigami interconnects triggered by stretching. Overcoming the mechanical limitation of rigid structure with kirigami technology, the designer SPIs exhibit high stretchability through out-of-plane structure deformation. Such kirigami-based interconnects can improve the elastic functionality of wearable RF electronics and offer high compatibility to large body motion in future body network systems.

With the increase of system complexity in wireless communications, higher requirements on miniaturization and integration are put forward for future antennas. Antennas of different frequency bands need to be placed together to achieve multiple communication goals. However, when a large-sized antenna operating at a low-band (LB) is used alongside a small-sized antenna operating at a high-band (HB), the radiation from the former can block the latter, thereby impacting the overall functioning of the antenna system. In this work, we propose a novel method for designing electromagnetic (EM) transparent antennas based on Drude metasurfaces. A dipole antenna made of Drude metasurfaces can maintain the radiation pattern of nearby HB antenna without compromising on radiation performance compared to the conventional metal-based one. An interconnected metasurface is designed to ensure low surface conductivity at HB yet high surface conductivity at LB, thus providing low radar cross section (RCS) compatible with the HB antennas. A prototype of the EM transparent dipole antenna is experimentally demonstrated and microwave measurements verify its capabilities in strong radiation and suppressing scattering at the LB and HB, respectively. Our results demonstrate an alternative way of solving EM blockages in multiband antenna systems by replacing conventional antennas with Drude-type meta-antennas.

Optical nonreciprocity, stemming from the deviation of the Lorentz reciprocity theorem, holds significant interest in the realm of optics and electromagnetics. Here, we propose and experimentally demonstrate broadband nonreciprocal transmission via a low-biased magnetic Kerker-type dimer metasurface. The designed magneto-optical metasurface comprises three layers of metal sandwiched between two gyromagnetic near-zero thickness slabs. The Kerker-type dimers broaden the isolation bandwidth utilizing multiple resonances where the double-stacked metallic disks act as Kerker-type dipoles, enhancing the transmissibility of the metasurface. The multipole decomposition reveals that the magnetic dipole contribution arising from magnetization is the primary cause of the metasurface's nonreciprocal response. Microwave measurement demonstrates that the bandwidth for an isolation ratio exceeding 10 dB is over 3 GHz. The broadband nonreciprocal performance remains relatively stable, exhibiting strong robustness against the bias disturbance. Our findings provide an alternative avenue for enhancing broadband nonreciprocity transmission under a low-biased magnetic field.

Orbital angular momentum (OAM) has recently attracted extensive attention in the radio frequency domain due to its potential applications in various areas. In the OAM-based communication system, the development of the OAM-generating antennas lies at the heart of the matter to generate and receive vortex beams. In this work, a multiplexing/demultiplexing millimeter-wave OAM antenna based on the traveling-wave circular loop structure is proposed and experimentally demonstrated. The feeding networks are implemented using waveguide ports which are inherent integration in millimeter wave communication systems. A prototype with OAM states l = ±3 carried by the z polarization and l = ±2 for the x and y polarizations at 60 GHz is fabricated and measured. Measured near-field distributions and far-field radiation patterns show excellent agreement with the simulated ones. Furthermore, based on the designer strategy, four coaxially propagating waves with OAM modes l = ±3 and ±5 for the z polarization component and l = ±2 and ±4 for the x, y polarization components are investigated, respectively. The antenna will have a positive effect on the application potential of OAM-based wireless communication.