Previous studies on orbital angular momentum (OAM) communication mainly considered line-of-sight environments. In this letter, however, it is found that OAM with high-order modulation can be achieved in highly reverberant environments by combining the multiplexing a spatial equalizer. The exhibits comparable performance of conventional multiple-input multiple-output (MIMO) system.

The emergence of metasurfaces provides a novel strategy to tailor the electromagnetic response waves in controlled manner by judicious design constitutive meta-atom. However, passive tend perform specific or limited number functionalities and suffer from narrow-frequency-band operation. Reported reconfigurable can generally be only 1D configuration use p-i-n diodes show binary phase states. Here, 2D reflective metasurface with individually addressable meta-atoms enabling continuous control...

The Airy beam, known to present particular unique features, such as diffraction-free, self-healing, and self-bending, has attracted considerable interest in recent years. Here, an electronically controlled reflective coding metasurface is exploited generate dynamically manipulate the beam over a wide frequency band microwave regime. By judiciously controlling external dc bias voltage applied programmable metasurface, two distinct control states, ``0'' ``1'', are engineered digital codes for...

Abstract Bessel beams have attracted considerable interest due to their intriguing nondiffraction and self‐healing properties. Such beam can be generated by conventional devices that are more or less subjected issues of low efficiency, complex manufacturing, bulky size. Here, an electronically engineered reflective metasurface is designed generate flexibly manipulate Bessel‐like over a broad frequency range in the microwave regime. Due dynamic resonance feature metasurface, phase profile...

This article proposes an analytical design methodology for different kinds of perfect absorbers (PAs) based on metagratings (MGs). In the specific analysis and design, period MG is chosen to ensure that there only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0^{\textrm {th}}$ </tex-math></inline-formula> order diffraction mode. Using established theory, supercell rigorously analyzed derive a load...

Vortex electromagnetic (EM) waves hold promise for their ability to significantly increase the transmission capacity of wireless communication systems via torsion resistance defined by different topological charges associated with orbital angular momentum (OAM). However, application vortex in remote distance is limited its characteristic divergence. In this paper, a lens based on phase-modulation metasurface (MS) proposed that enables EM converge, thereby improving propagation performance at...

A method of improving the diversity and capacity multiple-input-multiple-output (MIMO) systems in nonisotropic multipath environments by loading a scatterer array is proposed. The difference between super-resolution imaging discussed first. phase differences caused "effective space" adjacent antenna elements are critical factors enhancement. array, which made cross-structure periodically, placed on top to adjust center radiation pattern each port. By increasing "equivalent size" correlation...

Transformation optics (TO) concept well known for its huge possibility in patterning the path of electromagnetic waves is exploited to design a beam steering lens. The broadband directive in-phase emission desired off-normal direction from an array equally fed radiators numerically and experimentally reported. Such manipulation achieved without use complex bulky phase shifters as it case classical phased antennas. all-dielectric compact low-cost lens prototype presenting graded permittivity...

This paper presents a radar cross-section (RCS) reduction technique by using the coding diffusion metasurface, which is optimised through random optimization algorithm. The design consists of two unit cells, are elements ‘1’ and ‘0’. reflection phase between two-unit cells has 180° ± 37° difference. It working frequency band from 8.6 GHz to 22.5 GHz, with more than 9 dB RCS reduction. monostatic wider bandwidth metasurface as compared traditional chessboard metasurface. In addition, bistatic...

A kind of transmission–reflection-integrated elements and metasurfaces (MSs) are proposed to achieve full-space manipulation amplitudes, phases, polarization states electromagnetic (EM) waves. The MSs designed control the reflection transmission under same incident wave. By introducing an amplitude–phase regulation structure each element, can be simultaneously controlled by three geometric parameters elements, respectively. To demonstrate abilities regulate EM waves, working in mode, mode...

In this article, we demonstrate a new strategy for achieving kind of shape-controlled tunable microwave absorbers based on shape memory polymers (SMPs). Using the heat-driven effect SMPs, frequency-tunable absorber and magnitude-tunable are designed. Both designs consist periodic metallic array printed both sides FR4 substrate, SMPs' substrate (VeroWhitePlus) in middle layer, ground at bottom. The equivalent circuit models introduced to analyze operational principles two absorbers....

Complex electromagnetic structures can be designed by using the powerful concept of transformation electromagnetics. In this study, we define a spatial coordinate that shows possibility designing device capable producing an illusion on antenna radiation pattern. Indeed, compressing space containing radiating element, show it is able to change pattern and make location appear outside latter space. Both continuous discretized models with calculated parameter values are presented. A reduction...

In this paper, based on transformation electromagnetics, the design procedure of a lens antenna, which steers radiated beam patch array, is presented. Laplace's equation adopted to construct mapping between virtual space and physical space. The two dimensional (2D) method can be extended potential three-dimensional (3D) realization, with proper parameter simplification, further realized by common metamaterials or isotropic graded refractive index (GRIN) materials. Full wave simulations are...

Orbital angular momentum (OAM) vortex waves generated by conventional spiral phase plates and metasurfaces have been widely discussed. In this work, we propose an innovative OAM generation method based on transformation optics (TO). By solving Laplace's equation with specific boundary conditions, oblate cylindrical shaped physical domain is designed to imitate a gradient virtual which able generate beam upon reflection. As proof-of-concept demonstration, broadband all-dielectric microwave...

Quasi-conformal transformation optics is applied to design electromagnetic devices for focusing and collimating applications at microwave frequencies. Two are studied conceived by solving Laplace's equation that describes the deformation of a medium in space transformation. As validation examples, material parameters two different lenses derived from analytical solutions equation. The first lens produce an overall directive in-phase emission array sources conformed on cylindrical structure....

Correlations and mutual couplings in antenna arrays lead to performance deterioration of multiple-input-multiple-output (MIMO) systems. The relation between coupling correlation is complex, especially non-isotropic multipath environments. Reducing does not guarantee an eventual reduction the overall vice versa. In general, it a trivial task reduce simultaneously arbitrary this correspondence, planar metamaterial structure (PMS) array-antenna decoupling surface (ADS) are applied array for...

Spin-selective metamirrors consisting of planar meta-atoms are able to reflect tailored incident circularly polarized (CP) waves either in similar or opposite handedness while absorbing the other spin-wave. In this article, we propose a novel design metamirror exhibiting both spin-selective absorption and phase modulation properties. A chiral with asymmetric split-ring resonators (ASRRs) is proposed achieve reflection/absorption. Meanwhile, geometric introduced provide full <inline-formula...

The printed circuit board (PCB)-type metagrating (MG), a periodic microstrip planar structure with discrete distribution of polarization currents, can realize high-angle wavefront shaping near-unity efficiency for potential application in high beam-steering antennas or reflectors. For large-angle deflection, only small number meta-atoms are required the MG's period. As such, here, we focus on reflective PCB MG presence two meta-atoms, whose complex load impedance densities explicitly derived...

Tightly focusing cylindrical vector beams (CVBs) are widely used in diverse applications from particle trapping to high-resolution microscopy. Recently, planar metasurfaces have been proposed as promising alternatives traditional bulky optical devices for tightly focused CVB generation. However, few allow the generation and independent phase control of different CVBs. In this paper, cascaded dual-channel transmissive that can be simultaneously generate CVBs independently their phases...

Multibeam antenna (MBA) radiations provide linkages to multiple nodes and can bring enhanced communication quality with reduced power consumption for Internet of Things (IoT) applications. In this article, a novel method providing low-cost flexible MBA solution is proposed. Multiple orbital angular momentum (OAM) modes are used as internal excitations the antenna, generated beams pencil no OAM mode, which convenient IoT connection. First, aperture phase distributions that convert incident...

Superoscillation is an extraordinary phenomenon capable of generating small-size focusing spots, which can be used for super-resolution and imaging. Herein, we elaborate on a reconfigurable near-field reflector based the superoscillation principle, where focal position operation frequencies are modulated by dynamic phase-compensation mechanism engineered metamirror. A varactor diode embedded into each resonant meta-atom, enabling to achieve nearly 340° phase coverage. To validate proposed...

Metagratings are promising devices in various applications for their characteristics of simple structure, large steering angle, high efficiency, and multiband functionality. In this letter, we propose a new method the design dual-operation metagratings (DMGs) based on principle period-conversion wide-angle reflection. The DMG is realized by designing unit cell with dual-band capacitive response. As such, symmetrical can perform as one period at low frequencies two periods frequencies, thus...