Highly efficient Airy beam generator with high polarization purity by a receiving-transmitting metasurface.

This paper presents a highly efficient Airy beam generator at microwave frequency using a transparent metasurface with a receiving-transmitting scheme. The amplitude and phase of the transmitted orthogonal polarization wave can be flexibly controlled by orientation angles of receiving and transmitting patches of the proposed meta-atom. Utilizing this property to reshape the field of transmitted waves following the desired phase and amplitude profile of the Airy wave packet, an Airy beam generator is designed and experimentally demonstrated.

Experimental realization of a transmissive microwave metasurface for dual vector vortex beams generation.

This work presents a theoretical design and experimental demonstration of a transmissive microwave metasurface for generating dual-vector vortex beams (VVBs). The proposed metasurface consists of an array of pixelated dartboard discretization meta-atoms. By rotating the meta-atoms from 0° to 180°, a Pancharatnam-Barry (P-B) phase covering the full 360° range is achieved, with a transmittance exceeding 90% over the frequency range from 9.

Miniaturized leaky-wave antenna with backward-to-forward beam scanning and suppressed open stop-band based on substrate-integrated plasmonic waveguide.

This work presents a theoretical design and experimental demonstration of a novel miniaturized leaky-wave antenna (LWA) using composite waveguide based on substrate-integrated plasmonic waveguide (SIPW). The SIPW is designed by embedding hybrid dual spoof surface plasmon polariton (SSPP) structure into a three-layer substrate integrated waveguide (SIW). Due to the slow-wave effect of SIPW, the proposed miniaturized composite waveguide forms slowed phase velocity and decreased lower cutoff frequency.

Rapid design of hybrid mechanism metasurface with random coding for terahertz dual-band RCS reduction.

In this paper, a hybrid mechanism metasurface (HMM) employing 1-bit random coding is proposed to achieve polarization-insensitive and dual-wideband monostatic/bistatic radar cross section (RCS) reduction under a wide range of incident angles. The anisotropic unit cell is designed by the combination of the multi-objective particle swarm optimization (MOPSO) algorithm and Python-CST joint simulation, which facilitates the rapid acquisition of the desired unit cell with excellent dual-band absorption conversion capability. The unit cell and its mirrored version are used to represent the units "0" and "1", respectively.

Transmissive Pancharatnam-Berry metasurfaces with stable amplitude and precise phase modulations using dartboard discretization configuration.

Metasurfaces are ultra-thin artificial structures capable of flexibly manipulating electromagnetic (EM) waves. Among various applications, phase modulation of electromagnetic (EM) waves using metasurfaces holds great significance. The Pancharatnam-Berry (P-B) metasurfaces provides a complete 2π phase modulation by simply rotating the meta-atom.

Phase-to-pattern inverse design for a fast realization of a functional metasurface by combining a deep neural network and a genetic algorithm.

Metasurface provides an unprecedented means to manipulate electromagnetic waves within a two-dimensional planar structure. Traditionally, the design of meta-atom follows the pattern-to-phase paradigm, which requires a time-consuming brute-forcing process. In this work, we present a fast inverse meta-atom design method for the phase-to-pattern mapping by combining the deep neural network (DNN) and genetic algorithm (GA).

Topology optimization of the azimuth-rotation-independent polarization conversion metasurface for bandwidth enhancement.

Metasurfaces offer an unprecedented opportunity for flexible manipulation of electromagnetic wave. The azimuth-rotation-independent (ARI) polarization conversion metasurface (PCM) is an ultrathin device, which could convert an arbitrary linearly-polarized incident wave to its cross-polarized state. However, the bandwidth of an ARI PCM with a high cross-polarized transmission is usually limited.

Rapid customized design of a conformal optical transparent metamaterial absorber based on the circuit analog optimization method.

In this paper, a conformal optical transparent metamaterial absorber (COTMA) is proposed based on the circuit analog optimization method (CAOM), which can effectively enhance the optimization speed in the metamaterial absorber structure design by quantifying the equivalent circuit parameters. The operating frequency band can be customized at any band through CAOM, such as microwave, terahertz, and near-infrared frequencies. Here, a five-square-patch structure absorber with transparency and flexible properties is achieved.

Study of symmetries of chiral metasurfaces for azimuth-rotation-independent cross polarization conversion.

The realization of cross-polarization conversion has attracted great interest in polarization conversion metasurfaces (PCMs), particularly due to polarization manipulation of electromagnetic (EM) waves with small size and low loss. An azimuth-rotation-independent (ARI) cross-polarization converter is a kind of 90° polarization rotator, which can rotate the polarization of linearly polarized incident electromagnetic (EM) waves with an arbitrary polarization direction to the orthogonally polarized transmitted EM waves. In this paper, we study the symmetry properties of chiral metasurfaces using the Jones matrix method for ARI 90° polarization rotators.

Broadband extremely close-spaced 5G MIMO antenna with mutual coupling reduction using metamaterial-inspired superstrate.

A metamaterial structure, which has positive and negative permeability over a wide microwave frequency band, has a proposed structure that can be employed as a superstrate for reducing the mutual coupling of a MIMO antenna system. This MIMO antenna system consists of two extremely close-spaced antenna elements. The proposed structure's decoupling mechanism is verified by both the full-wave electromagnetic simulations and experiments, and the simulated and measured results agree very well with each other.

Experimental demonstration of a magnetically tunable ferrite based metamaterial absorber.

We synthesize and systematically characterize a novel type of magnetically tunable metamaterial absorber (MA) by integrating ferrite as a substrate or superstrate into a conventional passive MA. The nearly perfect absorption and tunability of this device is studied both numerically and experimentally within X-band (8-12 GHz) in a rectangular waveguide setup. Our measurements clearly show that the resonant frequency of the MA can be shifted across a wide frequency band by continuous adjustment of a magnetic field acting on the ferrite.

Tunable band notch filters by manipulating couplings of split ring resonators.

The couplings between single/dual split ring resonators (SRRs) and their mirror images in a rectangular waveguide are systematically investigated through theoretical analysis and experimental measurements. Such couplings can be manipulated mechanically by rotating the SRRs along a dielectric rod and/or shifting the SRRs up/down along the sidewall of the rectangular waveguide, resulting in shifts of the resonant frequencies and modulations of the resonant magnitudes. These controllable properties of SRRs pave the routers toward designing tunable band notch filters.

Active microwave negative-index metamaterial transmission line with gain.

We studied the active metamaterial transmission line at microwave frequency. The active composite right-handed or left-handed transmission line was designed to incorporate a germanium tunnel diode with a negative differential resistance property as the gain device at the unit cell level. Measurements of the fabricated planar transmission line structures with one-, two-, and three-unit cells showed that the addition of the dc pumped tunnel diodes not only provided gain but also maintained the left handedness of the transmission line metamaterial.

Active Microwave Metamaterials Incorporating Ideal Gain Devices.

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL) incorporating ideal gain devices such as constant negative resistance.