Epsilon-negative Medium Research Articles

A Dual-Band Metasurface Reflector Using Ring Resonator With Interdigital Capacitor

This research presents a metasurface reflector to support dual-band applications at 1.8 GHz and 5.5 GHz for LTE and WLAN, respectively. The proposed unit cell creating the metasurface has the property of an epsilon negative medium (ENG) that is one of the reflector requirements. The novel design of unit cells uses the ring resonator pattern associated with an interdigital capacitor to control resonant frequencies and relative permittivity. The epsilon negative medium can be controlled by using an interdigital capacitor that can create the electric field at the unit cell. Therefore, the size of the metasurface can be reduced from $\lambda $ /2 to $\lambda $ /4 which is much smaller than the conventional structure, resulting in a compact reflector when it works together with an antenna. The proposed unit cell was designed to obtain the dual-frequency operation with simulated bandwidth of 1.71 GHz - 2.48 GHz at 1.8 GHz and 5.15 GHz - 6.00 GHz at 5.5 GHz, respectively. The proposed metasurface was designed by using an array of $7 \times 7$ unit cells. The simulation and experimental results agree very well with the gains of 8.52 dB and 9.55 dB at 1.8 GHz and 5.5 GHz, respectively.

Epsilon-negative media from the viewpoint of materials science

A comprehensive review of the fundamentals and applications of epsilon-negative materials is presented in this paper. Percolative composites, as well as homogeneous ceramics or polymers, have been investigated to obtain the tailorable epsilon-negative properties. It's confirmed the anomalous epsilon-negative property can be realized in conventional materials. Meanwhile, from the perspective of materials science, the relationship between the negative permittivity and the composition and microstructure of materials has been clarified. It's demonstrated that the epsilon-negative performance is attributed to the plasmonic response of delocalized electrons within the materials and can be modulated by it. Moreover, the potential applications of epsilon-negative materials in electromagnetic interference shielding, laminated composites for multilayered capacitance, coil-less electric inductors, and epsilon-near-zero metamaterials are reviewed. The development of epsilon-negative materials has enriched the connotation of metamaterials and advanced functional materials, and has accelerated the integration of metamaterials and natural materials.

Design of narrow band multi-channel optical filters using zero index medium

We propose a design of narrow-band multi-channel optical filter using multiple stacks of unit cell consisting of trilayer of Doubly positive medium (DPS)–Doubly negative medium (DNG)–Epsilon negative medium (ENG). Finite Difference Time Domain (FDTD) technique is used to numerically simulate the effect of optical thickness of DPS, DNG and ENG media on tunability of the transmission spectrum of such a medium. We also demonstrate the control on the number of channels at different frequencies that can be transmitted through such medium.

Surface polaritons in grating composed of left-handed materials

In this work, we developed a unique mathematical model to solve dispersion relation for surface polaritons (SPs) in artificial composite materials grating. Here, we have taken two types of materials for analysis. In the first case, the grating composed of epsilon-negative (ENG) material and air interface. In second case, grating composed of left-handed materials (LHMs) and ENG medium interface is considered. The dispersion curves of both p and s polarized SPs modes are obtained analytically. In the case of ENG grating and air interface, polaritons dispersion curves exist for p-polarization only, whereas for LHM grating and ENG medium interface, the polaritons dispersion curves for both p and s polarization are observed.

Finite difference time domain formulation for epsilon-negative medium using wave equation

A novel approach utilizing one-dimensional (1D) wave equation based finite difference time domain (FDTD) formulations for Lorentz-type Epsilon-Negative (ENG) medium is developed. To demonstrate the validity and accuracy of the formulation, reflection of a plane wave normally incident at free space—ENG interface is compared with the analytical solution. Moreover, propagation characteristics of Lorentz-type ENG medium is investigated using the FDTD formulations both for wave equation and Maxwell's curl equations in 1D case. Comparisons of memory and computational time requirements of both formulations are given. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:304–310, 2016.

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Base on Epsilon Negative Medium

Random errors for a nonlocal Epsilon Negative medium

A medium embedded with finite length perfectly conducting needles can be taken as a nonlocal Epsilon Negative medium. The medium is nonlocal due to the presence of spatial dispersion. A theoretical analysis for effects of random errors in positioning and orientation of finite length needles upon the ensemble averaged nonlocal effective permittivity is presented. It is studied that an increase in positioning and orientation errors of needles can reduce and even eliminate the negative bandwidth. The word negative bandwidth is used to represent the range of frequency for which the real part of the effective permittivity is negative. Also these errors widen the bandwidth of an absorption peak associated with an imaginary part of the effective permittivity.

DESIGN AND ANALYSIS OF MULTICHANNEL TRANSMISSION FILTER BASED ON THE SINGLE-NEGATIVE PHOTONIC CRYSTAL

In this work, the multiple filtering phenomenon in a photonic crystal made of single-negative (SNG) materials is investigated. We consider a finite photonic crystal (AB)N immersed in air, in which A, B are epsilon-negative (ENG) and mu-negative (MNG) materials, respectively, and N is the stack number. It is found that such a photonic crystal can function as a multichannel transmission filter with a channel number equal to N−1. The required condition is that the thickness of MNG layer must be larger than that of ENG layer when magnetic plasma frequency is greater than electric plasma frequency. The channel frequencies can be red-shifted as the thickness of MNG layer decreases. The channel positions can be tuned by the incidence angle for both TE and TM polarizations. That is, the peak frequency is blue-shifted when the angle of incidence increases. Additionally, the influence of the static permeability of ENG medium and permittivity of MNG medium is also illustrated. The proposed structure can thus be used to design as a tunable multichannel filter which is of technical use in signal processing.

Zero-reflection metal slabs: A mechanism of light tunneling in metamaterials

Thick metals are nearly opaque due to high reflectance and the huge third-order nonlinear susceptibility of metals is hardly utilized. In the present paper, zero-reflection phenomena in a thick metal (M) slab covered with one-dimensional dielectric photonic crystals (PC’s) (CD)n are studied in heterostructures M(DC)n and sandwiched structures (CD)nM(DC)n. Visible-light tunneling modes can be realized in M(DC)n or (CD)nM(DC)n in which the optical epsilon-negative medium (metal) is paired with the PC, which mimics a lossless optical mu-negative medium in the gap region. The transmittance as high as 33% and 38% are observed at wavelength of 589 nm for M = Ag, with thickness d=60.2 nm in a heterostructure and d=83.1 nm in a sandwiched structure, respectively. The transmittance is more than 200 times larger than that of a single Ag layer with the same thickness in the latter case. Possible applications on metal-based nonlinearity enhancement and optical absorber are also discussed.