Double Negative Region Research Articles

Electromagnetic absorption of SRR based double-inverse E-Shaped metamaterial for DCS, EESC, 5G, and WiMAX applications

Herein, a novel double-inverse E-structured resonator metamaterial (MTM) surrounded by split-ring resonators (SRRs) is introduced and proposed. The proposed MTM has working frequency ranges of 1.62 – 1.79 GHz, 2.08 – 2.21 GHz, 4.39 – 4.99 GHz, and 5.65 – 6.09 GHz. In addition, the proposed MTM can be applied in digital cellular system uplinks (DCS) (1.736 GHz), earth exploration-satellite communication (EESC) (2.148 GHz), lower band 5G (4.8 GHz), and WiMAX (5.89 GHz) applications. The electromagnetic radiation reduction performance of the proposed MTM is investigated at 900 MHz and 1800 MHz of GSM cellular bands. The Finite Integration Technique (FIT) based on high-frequency electromagnetic software is utilised for the development of design along with a detailed investigation of the MTM properties. The proposed MTM is formed by developing a double-inverse E-structure in the middle surrounded by SRRs. The resonator structure with SRRs is implemented on an epoxy resin FR4 substrate, which has a compact size of 11.11 × 11.11 mm2. The unit cell has a high effective medium ratio of 14.82. Furthermore, the developed MTM shows a negative refractive index region from 3.124 to 6.98 GHz and double-negative region from 3.94 to 4.57 GHz, 5.26 to 5.49 GHz, and 6.29 to 6.88 GHz. In addition, SAR evaluation is also performed to test the competence of utilising the proposed MTM on modern mobile phones. The MTM has an electromagnetic absorption rate of about 44% and 43% at 900 MHz and 1800 MHz, respectively, for 1g whereas about 43% and 44% at 900 MHz and 1800 MHz, respectively, for 10g. Thus, the performance and characteristics of the developed MTM can be utilised for the above-mentioned applications.

A tri-band left-handed meta-atom enabled designed with high effective medium ratio for microwave based applications

This paper represents a tri-band left-handed meta-atom with high effective medium ratio, which is applicable for tri-band microwave based communication applications. The proposed meta-atom consists of modified complementary split ring resonator (CSRR) with two pi shaped metal strip loaded in the inner side. It shows the behavior of negative permeability and permittivity at 2.85 GHz, 4.83 GHz, 8.39 GHz, and 11.42 GHz resonance frequencies and extracted the double negative (DNG) metamaterial properties. The designed meta-atom dimension is 0.076λ×0.076λ at lower resonance frequency. To develop and analyze the offered meta-atom, the electromagnetic (EM) simulator CST Microwave Studio and MATLAB software were used. The equivalent circuit with RLC components of the proposed metamaterial unit cell is also investigated through ADS simulator and comparing S parameter (transmission coefficients) results with CST results. Analysis and comparison have been carried out with different configurations, such as various design structures, distinct substrate, changing the gap of the splits, and various array measures. All the array configurations proved that the frequency of operation is in the S-, C-, and X-bands. The designed meta-atom has double negative regions of 2.89–2.96 GHz, 4.84–4.99 GHz, 8.42–8.49 GHz, and 11.43–12.32 GHz, with the regions of effective negative refractive index 2.85–3.09 GHz, 4.83–5.36 GHz, 8.40–8.57 GHz, and 11.40–12.55 GHz, respectively. The effective medium ratio is 13.16; this implies that the proposed miniaturized meta-atom design is efficient and compact. The scattering parameter dimension of the meta-atom promising for the microwave based applications at S-, C-, and X-bands.

A complementary split ring resonator based metamaterial with effective medium ratio for C-band microwave applications

A complementary split-ring resonator (CSRR) based metamaterial is designed and investigated in this paper for microwave applications with effective medium ratio. This CSRR is the modification of the conventional split-ring resonator. Three square split-ring resonators (SSRR) are interconnected with a strip line as well as two splits in three square split-ring resonators are applied to increase the electrical length and coupling effect. The CSRR has an impact on the extraction of effective permittivity, permeability, and refractive index. The dimension of the designed unit cell is 5.5 × 5.5 mm2 that is printed on FR4 material. An 18 × 20 array structure is also investigated in this paper. The unit cell has a double negative region of 6.34–7.39 GHz and 8.20–9.98 GHz with effective negative refractive index region of 4.23–7.32 GHz and 7.40–10.0 GHz. The effective medium ratio is 8.0, which implies the effectiveness and compactness of the proposed CSSR design. The compact size, effective parameters, and effective medium ratio rate represent the suitability of the proposed metamaterial for practical C band microwave applications.

Design of A Two-Dimensional “T” Shaped Metamaterial with Wideband, Low Loss

A novel two-dimensional (2D) metamaterial structure with center symmetric “T” shaped unit is designed, fabricated, and measured in this paper. The proposed metamaterial comprises of a 2 × 2 array of area 4.3 mm × 4.3 mm, etched on single side of FR4 substrate. The simulation and measurement show that the novel metamaterial has a double negative range frequency of 20.16-37.47 GHz with an absolute width of 17.31 GHz, relative width of 60.07%, small unit loss of 0.16 dB, and small size of 0.07 λ 0 in 2D. Furthermore, the double negative region of the proposed metamaterial operates through K band and Ka band, it can be widely used in satellite communication and broadband digital transmission.

Measuring noise in microwave metamaterials

Electromagnetic metamaterials are artificially constructed media composed of arrays of electrical circuits that can exhibit electric and magnetic characteristics unlike those of any conventional materials. However, the materials are lossy and hence noisy, so that the signal-to-noise ratio in practical situations is greatly reduced. In particular, operating in the double negative region, where both the permittivity and the permeability are negative so that the refractive index is real but negative, incurs significant loss and noise penalties. In this work, we report noise measurements on a double negative metamaterial at microwave frequencies and compare them with the results of a simple model based on a transmission line loaded with lossy elements that mimic the split ring resonators and fine wires of the metamaterial. A noise source is associated with the resistive part of each element, and these are added incoherently to predict the total noise spectrum of the metamaterial. The theoretical results are in good agreement with the measurements. In particular, we find that the measured noise spectrum has contributions from both electric and magnetic noise, but is dominated by the magnetic noise. This limits possible applications, even with optimised materials, to functions that cannot be realised by conventional means.

Flexible paper substrate based wide band NRI metamaterial for X‐band application

AbstractA wide band flexible substrate based metamaterial is presented. The metamaterial is fabricated on photo paper using conductive nanoparticle ink targeting flexibility applications. The metamaterial structure shows a wide double negative region of 1.848 GHz (8.298–10.146 GHz). The transmission coefficient of the proposed metamaterial has been measured and verified with simulated one. The perceptible novelties of the proposed work are its simplicity, cost effectiveness, and flexibility with covering wide X‐band microwave spectra.

A Printed Xi-Shaped Left-Handed Metamaterial on Low-Cost Flexible Photo Paper.

A Xi-shaped meta structure, has been introduced in this paper. A modified split-ring resonator (MSRR) and a capacitive loaded strip (CLS) were used to achieve the left-handed property of the metamaterial. The structure was printed using silver metallic nanoparticle ink, using a very low-cost photo paper as a substrate material. Resonators were inkjet-printed using silver nanoparticle metallic ink on paper to make this metamaterial flexible. It is also free from any kind of chemical waste, which makes it eco-friendly. A double negative region from 8.72 GHz to 10.91 GHz (bandwidth of 2.19 GHz) in the X-band microwave spectra was been found. Figure of merit was also obtained to measure any loss in the double negative region. The simulated result was verified by the performance of the fabricated prototype. The total dimensions of the proposed structure were 0.29 λ × 0.29 λ × 0.007 λ. It is a promising unit cell because of its simplicity, cost-effectiveness, and easy fabrication process.

Resonance Characteristics and Effective Parameters of New Left Hand Metamaterial

It is essential to alter effective electromagnetic parameters of a material to enhance its response. In the present work, we propose a novel Left Hand Metamaterial (LHM) structure comprising dual turn spiral resonator (DTSR) and capacitance loaded strips (CLS). This structure is numerically explored to examine the resonance and effective material parameters i.e. permeability and permittivity. The negative refraction in the unit cell is confirmed with identification of double negative region (negative permittivity, e and negative permeability, µ ) on placing the unit cell in a waveguide with well defined Perfect Electric Conduction/Perfect Magnetic Conduction boundary conditions.

Resonance Characteristics and Effective Parameters of New Left Hand Metamaterial

It is essential to alter effective electromagnetic parameters of a material to enhance its response. In the present work, we propose a novel Left Hand Metamaterial (LHM) structure comprising dual turn spiral resonator (DTSR) and capacitance loaded strips (CLS). This structure is numerically explored to examine the resonance and effective material parameters i.e. permeability and permittivity. The negative refraction in the unit cell is confirmed with identification of double negative region (negative permittivity, ε and negative permeability, µ ) on placing the unit cell in a waveguide with well defined Perfect Electric Conduction/Perfect Magnetic Conduction boundary conditions.

Frequency Response of a Ferroelectric Material in Double-Negative Region

In this work, we investigate the far-infrared wave properties for a ferroelectric material, i.e., lithium tantalateðLiTaO3Þ, in the double-negative region, i.e., both the real parts of permittivity and permeability are negative. The analysis has been done based on the calculated surface impedances for three model structures, i.e., material occupying semi-infinite space (structure I), material of a slab immersed in free space (structure II), and a layered structure made of film on a dielectric substrate (structure III). It is found that the surface impedance spectrum exhibits resonant behavior. In structure I, there are only two resonant points, which arise mainly from the pole of permeability and the zero of permittivity. In structure II, multiple resonances can be found, and they strongly rely on the film thickness. Finally, we specifically investigate the substrate resonant phenom- enon in structure III.

Double-negative acoustic metamaterial based on hollow steel tube meta-atom

We presented an acoustic “meta-atom” model of hollow steel tube (HST). The simulated and experimental results demonstrated that the resonant frequency is closely related to the length of the HST. Based on the HST model, we fabricated a two-dimensional (2D) acoustic metamaterial (AM) with negative effective mass density, which put up the transmission dip and accompanied inverse phase in experiment. By coupling the HST with split hollow sphere (SHS), another kind of “meta-atom” with negative effective modulus in the layered sponge matrix, a three-dimensional (3D) AM was fabricated with simultaneously negative modulus and negative mass density. From the experiment, it is shown that the transmission peak similar to the electromagnetic metamaterials exhibited in the double-negative region of the AM. We also demonstrated that this kind of double-negative AM can faithfully distinguish the acoustic sub-wavelength details (λ/7) at the resonance frequency of 1630 Hz.

Analysis of composite nanoparticles with surface integral equations and the multilevel fast multipole algorithm

Composite nanoparticles involving multiple parts with different material properties are analyzed rigorously with surface integral equations and the multilevel fast multipole algorithm. Accuracy and efficiency of the developed parallel implementation are demonstrated on spherical objects with dielectric, perfectly conducting, plasmonic, and double-negative regions. Significant effects of the formulation on numerical solutions are also considered to show the tradeoff between the efficiency and accuracy.

Novel electromagnetic radiation in a semi-infinite space filled with a double-negative metamaterial

We have theoretically investigated the electromagnetic radiation excited by a charged particle moving along a semi-infinite space filled with a double-negative metamaterial (DNM). Cherenkov radiation in the double-negative region exhibits reversed or backward radiation behavior. The spectral density of reversed Cherenkov radiation has a continuous distribution over the radiation frequency region. The influence of some important parameters on the Cherenkov radiation energy per unit length has been discussed. The surface wave in the vacuum region presented here also is investigated. We conclude that the amplitude of the surface wave is greatly enhanced over some normal dielectric material cases. The enhanced surface wave may be useful for high frequency and high power vacuum electron devices with the DNM.

Analysis of Double-Negative (DNG) Bandwidths for Metamaterials Composed of Three-Dimensional Periodic Arrays of Two Different Magnetodielectric Spheres Arbitrarily Arranged on a Simple Tetragonal Lattice

Based on the theory describing traveling waves on three-dimensional (3-D) periodic arrays of two sets of magnetodielectric spheres arbitrarily arranged on a simple tetragonal lattice, dispersion diagrams of seven different arrangements of the spheres are analyzed for three combinations of sphere types: I) dielectric spheres with equal permittivity but different radius; II) dielectric spheres with equal radius but different permittivity; and III) one set of spheres is purely dielectric while the other set is magnetic. Results show that the maximum bandwidths of the DNG region provided by different spheres arrangements for spheres combinations I-III are, respectively, 0.21%, 0.069%, and 7.403%. Compared to results reported in previous literature, analysis of these possible arrangements of the spheres shows similar narrow double-negative (DNG) bandwidths for spheres combinations I and II, and wider DNG bandwidths for spheres combination III. Although purely dielectric materials with relative permittivity much greater than one are readily available, the usefulness of purely dielectric DNG metamaterials still depends on whether the narrow bandwidths achievable are acceptable for the particular applications. Since purely magnetic materials with relative permeability much greater than one above 1 GHz are not currently available, the practicality of fabricating DNG metamaterials using arrays with spheres combination III is questionable for radio frequency (RF) applications, at least at present, despite the fact that this combination yields much wider DNG bandwidths than those of spheres combinations I and II.

Left-Handed Properties of Metal-Ferrite Composites Placed into Waveguide in Millimetric Wave Range

Propagation of the electromagnetic wave of millimeter wavelength through the composite media formed by alternated ferrodielectric and metal elements, embedded into waveguide, has been investigated. It was shown experimentally that the composite media demonstrate left-handed properties in certain frequency region (Double Negative Region), depended on the static magnetic field. The magnification of transmittance of structures under study has been detected and analyzed.

MICROSTRIP ANTENNA'S GAIN ENHANCEMENT USING LEFT-HANDED METAMATERIAL STRUCTURE

The design, simulation and fabrication of a left-handed metamaterial (LHM) structure is presented. The combination of the modifled square rectangular Split Ring Resonator (SRR) and the Capacitance Loaded Strip (CLS) were used to obtain the negative value of permeability, and the negative permittivity, . Nicolson- Ross-Wier approach was used to identify the double negative region. A good agreement between simulated and measured results has been achieved. Upon incorporation with a single patch microstrip antenna, the performance of the antenna was improved where the gain of the microstrip antenna was increased up to 4dB, and its bandwidth widens from 2.9% to 4.98%. These improvements are due to the negative refraction characteristics of the LHM structure that acts as a lens when placed in front of the antenna.