Metamaterials: Reshape and Rethink

Metamaterials are composite materials whose material properties(acoustic, electrical, magnetic, or optical, etc.) are determined by their constitutive structural materials, especially the unit cells. The development of metamaterials continues to redefine the boundaries of materials science. In the field of electromagnetic research and beyond, these materials offer excellent design flexibility with their customized properties and their tunability under external stimuli. In this paper, we first provide a literature review of metamaterials with a focus on the technology and its evolution. We then discuss steps in the industrialization process and share our own experience.

Secure Beamforming Design for SWIPT in MISO Full-Duplex Systems

This paper investigates the problem of bi-directional secure information exchange for a multiple-input single-output(MISO)broadcast channel in presence of potential and external eavesdroppers capable of decoding the confidential messages.Specifically,a multi-antenna base station(BS)simultaneously sends wireless information and power to a set of dual-antenna mobile stations(MSs)using power splitters(PSs)in the downlink and receives information in the uplink in full-duplex(FD)mode.We address the joint design of the receiver PS ratio and the transmit power at the MSs,the artificial noise covariance,and the beamforming matrix at the BS in order to guarantee the individual secrecy rate and energy harvesting constraints at each receiver,and the signal-tointerference plus noise ratio(SINR)at the BS and MSs.Using semidefinite relaxation(SDR)technique,we obtain solution to the problem with imperfect channel state information(CSI)of the self-interfering channels.Simulation results are presented to demonstrate the performance of our proposed scheme.

Propagation of Electromagnetic Wave through Anisotropic Graded Refractive Index Profile

Propagation of electromagnetic wave (EW) through multilayer structure consisting anisotropic layers with gradient refractive index material is studied theoretically. Analytical solution for linear dependence of refractive index profile is examined. The structure consist the forbidden gaps, which are sensitive to parameters of refractive index profile.

Whispering Gallery Modes Formed by Scattering of an Electromagnetic Plane Wave by Two Cylinders

We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder.

Magnetic-Field Effects on Donor Impurity States in a Quantum Well

Green’s function technique is used to obtain the solution of Shredinger equation for impurity states in a quantum well (QW) under the magnetic field. Binding energy of impurity states is defined as poles of the wave function. We studied effects of the magnetic field magnitude and impurity position on the binding energy. The calculations were performed for both ground and excited states. The dependences of binding energies versus impurity position and magnetic field are presented for GaAs/Al0.3Ga0.7As QW.

Planar Magnetic Metamaterial Slabs for Magnetic Resonance Imaging Applications

A type of planar magnetic metamaterial is proposed with a square winding microstructure as a superlens for magnetic resonance imaging （MRI） applications. A direct magnetic field mapping measurement demonstrates that the radio-frequency magnetic field passing through the superlens is increased by as high as 46.9% at the position of about 3 cm behind the superlens. The resonance frequency of the fabricated slabs is found to be in good agreement with the target frequency （63.6 MHz） for a 1.5 T MRI system. MRI experiments with the magnetic superlens show that the intensity of the image and the SNR （signal-to-noise ratio） are both enhanced, implying promising MRI applications of our planar magnetic superlens.

Metamaterials beyond negative refractive index： Applications in telecommunication and sensing

Metamaterials have earned their name with extraordinary properties such as negative refractive index and invisibility cloaking. With over 15 years of research and development, metamaterials show their debut in real world applications, especially in the areas of telecommunication, sensing, aerospace & defense, optics and medical instrumentation. In the meanwhile, metamaterials are expanding their concept in areas beyond electromagnetics. In this paper, the authors would like to focus on the research and applications in telecommunication and sensing. Octave-bandwidth horn antennas, flat-panel satellite antennas and air-borne holographic satellite antennas are all fabulous examples of clever implementation that bring metamaterials into practical devices. We would like to discuss the features that differentiate metamaterials from conventional counterparts in case studies. With the advancement in design, manufacturing, packaging, detection and testing, more sophisticated features are expected in the telecommunication, sensing, and beyond.