Double Negative Properties Research Articles

A Bandwidth and Gain Enhanced Hexagonal Patch Antenna using Hexagonal Shape SRR

In the evolving digital era, the primary focus of the telecommunications industry is on the 5G network, expected to deliver high data rates, low latency, large network capacity, and improved connectivity. This article discusses efforts to adopt optimal frequencies for 5G, introducing techniques to enhance the characteristics of microstrip antennas using Double Negative (DNG) metamaterial properties. The hexagonal-shaped Split Ring Resonant (HSRR) metamaterial is considered a potential method to increase the bandwidth and gain of 5G antennas. Simulation of HSRR unit cells shows a positive impact on DNG characteristics. Meanwhile, the antenna design incorporating HSRR superstrate elements significantly increases gain to 4.47 dBi, and the implementation of HSRR structures on the groundplane results in a remarkable 368% increase in bandwidth compared to conventional antennas without metamaterial.

Tuneable double negative (DNG) Tri-Hexagonal split ring resonator metamaterial for 5G application

This paper introduces a compact tuneable metamaterial (MTM) unit cell featuring a tri-hexagon and tri-square split ring resonator (THTSSSR) structure designed for 5G communication applications. Metamaterials are employed to achieve unique electromagnetic properties not found in natural materials. The design process involves the arrangement of three square rings and three hexagon rings as metallic patches on a Rogers substrate (RT 5880), measuring 7 x 7 mm2 with a thickness of 1.575 mm. The proposed design exhibits double negative (DNG) properties, with resonances in the transmission coefficient (S21) at 3.493 GHz and a bandwidth of −10 dB covering frequencies between 3.057 and 3.711 GHz. Numerical simulations conducted using finite-integration techniques (FIT) in CST Microwave Studio validate the design's effectiveness, with confirmation through the Advanced Design System (ADS). The MTM unit cell demonstrates tuneable attributes, including negative permittivity ranging from 3.39 to 5 GHz and negative permeability from 3.39 to 3.86 GHz. These findings highlight the compactness and tunability of the proposed design, making it promising for 5G communication applications.

Modified Lossy epsilon-negative CuCr2Se4 toward single-phase metamaterials with double negative parameters via Zn doping

With Zn doping, the electron concentration of CuCr2Se4 decreases, the penetration depth of electromagnetic wave increases. The double negative properties were achieved in Cu0.8Zn0.2Cr2Se4 and Cu0.6Zn0.4Cr2Se4.

Development of double-layer metamaterial with high effective medium ratio values for S- and C-band applications

This study introduces a compact double negative metamaterial (DNM) composed of three split rings connected slab resonator (TSRCSR) based double-layer design with a high 13.9 EMR (effective medium ratio) value. A double-layer patch is introduced to achieve the novel double negative properties, including negative behaviours of effective medium parameters, including refractive index, permittivity, and permeability with a high effective medium ratio for the miniaturised size of the introduced unconventional material that is highly suitable for microwave S and C band covering applications. The popular low-loss Rogers RT5880 (thickness 1.575 mm) substrate and copper resonator materials are utilized to develop the metamaterial unit cell that offers triple resonance between frequencies from 1 to 8 GHz. Therefore, the proposed metamaterial exhibits resonance peaks at 2.75, 5.2, and 6.3 GHz, suitable for radar, communication satellite, and long-distance telecommunication applications, respectively. The commercially available simulator known as Computer Simulation Technology (CST) is adopted to develop and simulate the 8 × 8 mm2 metamaterial design. The simulation results of the introduced TSRCSR design structure were verified by adopting the Ansys High-Frequency Structure Simulator (HFSS). Furthermore, it was then proved with the help of equivalent circuit model findings gained from the Advanced Design Structure (ADS) software. On the other hand, the analytical results were further validated by measuring the TSRCSR design utilizing a Vector Network Analyzer (VNA). These analyses become one of the novelties of this work, where the compact TSRCSR metamaterial successfully gained small discrepancies in transmission coefficient values when compared to both analytical and measurement results. The proposed metamaterial is highly suggested for communication devices for its extensive effective characteristics and compactness.

Enhancement of off-body communications with a low-SAR, high-gain multiband patch antenna designed with a quad-band artificial magnetic conductor

Abstract The increasing demand for wireless communication has emphasized the need for multiband antennas. This study presents a novel design for a multiband antenna with reduced specific absorption rate (SAR), high gain, and improved front-to-back ratio (FBR) achieved through the integration with a 4 × 4 artificial magnetic conductor (AMC) surface. The proposed antenna covers a wide range of wireless frequency bands, including Industrial, Scientific, and Medical, Wireless Local Area Network, Worldwide Interoperability for Microwave Access, Wi-Fi 6E, and 7, with resonating frequencies at 2.4, 3.2, 5.5, 7.5, and 10 GHz. The AMC unit cell creates four zero-degree reflection phases with double negative properties at 2.5, 3.8, 5.5, and 7.5 GHz. The compact design measures 0.23λ0 × 0.296λ0 × 0.0128λ0 and placed 0.104λ0 above an AMC surface of size 0.512λ0 × 0.512λ0 × 0.1296λ0. This structure enhances the gain by up to 8.55dBi at 6.01 GHz. The proposed antenna has −10 dB impedance bandwidth for these corresponding frequencies viz 2.34–2.43 GHz (3.77%), 2.81–3.83 GHz (30.72%), 4.82–6.21 GHz (25.20%), 7–7.65 GHz (8.87%), and 8.06–10.31 GHz (24.5%). An overall average percentage reduction value of SAR taken at these frequencies has been found to be 96.11% with AMC structure. The antenna sample was successfully fabricated, and the experimental results have been found to match well with the simulation results. This integrated design offers a promising solution for wearable off-body communication devices.

Estimating effective acoustic properties of various configuration of perforated panels

Acoustic metamaterial attains uncommon material properties over natural material such as negative effective mass density, negative effective bulk modulus, or both. To start with, the present research demonstrates and establishes robust method to estimate and measure acoustic metamaterial properties of a Helmholtz resonator analytically using transfer matrix (TM) method and experimentally in detail. The proposed method extracts the reflection and transmission coefficients from corresponding TM to evaluate the effective acoustic metamaterial properties. For a single Helmholtz resonator, the effective bulk modulus has been observed negative; however, the effective density remains positive. In order to attain double negative material properties, the perforated panel (PP) and microperforated panel (MPP) have been introduced in parallel to resonator. The 1D electro-acoustic modeling has been carried out for all configurations to estimate effective properties analytically. Successively, the experiments have been conducted to measure the effective properties from acoustic metamaterial prospective. The analytical and experimental investigations on five different cases reveal that one can attain negative effective compressibility and effective density by cascading two PPs or MPPs with a finite duct. Moreover, by backing a Helmholtz resonator from both sides with two PPs or MPPs in parallel, one can attain double negative properties comparatively higher than earlier configuration in low-frequency zone in broadband. In total, eight different configurations have been investigated analytically and experimentally, where it has been demonstrated that the proposed compact model is more effective than a finite array of same Helmholtz resonators.

A double negative (DNG) metamaterial based on parallel double-E square split resonators for multi-band applications: Simulation and experiment

In this paper, we designed and investigated a parallel double-E shaped structure based on double negative (DNG) metamaterial (MTM) both numerically and experimentally, which can be utilized for multiband applications. We used the Computer Simulation Technology (CST) Microwave Studio electromagnetic simulator to design the MTM and obtain the numerical results. The proposed MTM has a unit cell dimension of 8 × 8 × 1.57 mm3, and Rogers RT 5880 was used as the substrate, resulting in a high effective medium ratio (EMR) value of 15.61. The DNG metamaterial can cover multiband frequencies (S and C bands) and produce three resonance frequencies of 2.40, 4.50, and 7.24 GHz. Parametric studies were performed for different configurations by changing the type of substrates, substrate thicknesses, split gaps, and unit cell arrays to optimize the proposed design. An equivalent circuit was validated using the advanced design system (ADS) software and compared to the CST simulated results, which showed good agreement. The proposed structure is highly significant due to its low profile (small size) and ordinary resonator arrangement, which produced double negative properties with a high EMR over a wide range of frequencies. The recommended structure can be useful for different applications such as wireless communications, weather radar, satellite communication, and wireless sensor networks.

Multiple Re‐Entrant Star‐Shaped Honeycomb with Double Negative Parameters and Bandgap Properties

Achieving bandgaps and double negative properties with single‐phase metamaterial in the low‐frequency range remains a challenge. Currently, acoustic metamaterials with double negative parameters are made of different materials, which can limit their application and design. Herein, a single‐phase multiple re‐entrant star‐shaped honeycomb (MRSSH) is designed and the double negative parameters and bandgaps are simulated. The numerical results show that the MRSSH exhibits three bandgaps and double negative characteristics (negative effective mass density and negative effective modulus) within a certain frequency range. The formation mechanics of bandgaps are investigated by analyzing the vibration modes. Moreover, the effects of geometry parameters such as internal concave angle and re‐entrant on the bandgaps and vibration modes of the MRSSH are investigated. By adjusting the geometry parameters, the dispersion curves and bandgap distribution can be tuned simultaneously. This study provides a new idea for designing a single‐phase lightweight metamaterial that can apply to noised reduction, vibration control, and super‐resolution imaging.

Artificial neural network based metasurface inspired planar frequency reconfigurable antenna for wireless applications

The growing interest in attaining various appealing features of wireless communication systems has motivated researchers to design innovative antennas. This paper analyzes the behavior of a low profile artificial neural network-based metasurface (MS) inspired two-layered frequency reconfigurable antenna (ANN-MSFRA) using planar technology. The designed two-layered structure is a combination of two substrates mounted one above the other, having no air gap between them. The prototype of the proposed antenna is fabricated on Rogers RO4350B material having permittivity (εr) = 3.48, and thickness (h) = 1.524 mm. The MS is represented as an artificially generated periodical array of H and I-shaped metallic inclusions. Numerically analyzed results validate the double negative properties of metamaterial. To verify the effectiveness of the projected two-layered approach, the performance of the reconfigurable antenna is analyzed through both simulations and measurements. The antenna successfully reconfigures the operating frequency from 4.86 to 5.89 GHz, covering the operating bandwidth of 1.03 GHz with a fractional tuning range of 19.1%. The presented simulated and measured outcome provides a positive correlation.The developed ANN model suggested for the estimation of specific output parameters shows minimum error during analysis and synthesis.

Deformation regulated flexible carbon foam matrix intrinsic metamaterials

Designing adjustable intrinsic metamaterials with double negative electromagnetic properties has been a challenging subject. The flexible carbon foam matrix intrinsic metamaterials whose double negative properties can be regulated by deformation are successfully synthesized. The metamaterial properties convert from positive to negative and continuous transition from weak to strong can also be realized through deformation regulation, which confirmed the characteristics of intelligent regulation and controllable response in the carbon matrix intrinsic metamaterials. It is revealed by SEM analysis that a large number of micropores and closed loops constituted by three-dimensional porous network skeletons of carbon foam become denser under deformation regulation, which is advantageous for the appearance of negative permittivity and negative permeability. This research provides essential inspirations for the exploration of intelligent metamaterials such as controllable polarization converters and hybrid integrated circuit switches.

Tunable band gaps and double-negative properties of innovative acoustic metamaterials

Tunable band gaps and double-negative properties of innovative acoustic metamaterials

Metallic ferromagnetic selenospinel composites of CuCr2Se4–CdCr2Se4 with double negative electromagnetic parameters

Random metamaterial with negative electric permittivity (ε < 0) and negative magnetic permeability (μ < 0) is a group of attractive alternatives to ordered double negative metamaterials (DNMs) with periodic unit cells; however, the preparation of random DNMs with a relatively convenient preparation process and their electromagnetic property adjustment are of challenge. Here, we report the preparation of metallic ferromagnetic selenospinel composites, xCdCr2Se4·(1−x)CuCr2Se4, from metallic powders by using a simple solid-state reaction process, and double negative ε and μ have been observed in the frequency range of 120–650 MHz for 0.2CdCr2Se4·0.8CuCr2Se4 and 73–520 MHz for 0.4CdCr2Se4·0.6CuCr2Se4. The negative ε is owing to the plasmonic state of delocalized carriers in the metallic ferromagnetic CuCr2Se4, which can be described with the Drude model. The suppression of the magnetic resonance induced by the eddy current has been alleviated by the proper addition of the paramagnetic semiconductor CdCr2Se4. A theoretical model deduced from Maxwell's equation has been constructed based on the skin effect to elucidate the magnetic resonance-dependent negative permeability. Our work introduces the metallic ferromagnetic chalcospinels into the field of random DNMs and sheds light on the theoretical understanding and tuning mechanism on the double negative properties.

Polarization-independent multiband double-negative metamaterial through ferrite-based flexible substrate with tunable microwave dielectric properties

Microwave flexible dielectric materials offer a new set of attractive applications for modern devices as well as for metamaterial research and technology. In this article, metamaterials with double-negative characteristics fabricated on a novel flexible dielectric substrate are presented. These novel flexible microwave substrates were prepared from Mg-Zn ferrite powder. The proposed flexible metamaterials offer double-negative (DNG) properties, polarization insensitivity, and a higher effective medium ratio (EMR) for multiple bands of application. The prepared, flexible substrates exhibit performance superior to commercial materials with tunable dielectric properties, and the proposed metamaterial structure enhances the antenna performances as well. The flexible substrates are synthesized from Mg-Zn ferrite having two different molecular compositions of Mg denoted as Mg40 and Mg60. The prepared, highly flexible, and lightweight magnesium zinc ferrites of Mg40 and Mg60 possess tunable dielectric properties with relative dielectric permittivity of 5.18 and 4.20 and dielectric loss tangents of 0.004 and 0.006, respectively. The double-negative (DNG) metamaterial behavior is observed with the fabricated flexible metamaterials at 2.92 GHz, 4.42 GHz, 7.75 GHz, and 9.84 GHz for Mg40 and 3.16 GHz, 4.71 GHz, 8.21 GHz, and 10.52 GHz for Mg60 and validated by using 3D electromagnetic Simulator CST (Computer Simulation Technology) Microwave Studio and ADS (Advanced Design System) software. Therefore, the prepared, flexible metamaterials having improved EMR, polarization insensitivity, and DNG properties on a MgZnFe2O4substrate are suitable additions to the field of the flexible microwave.

“Quad-band flexible magnesium zinc ferrite (MgZnFe2O4)-based double negative metamaterial for microwave applications”

This article presents vertically coupled, rectangular complementary split-ring resonator-shaped quad-band double-negative (DNG) metamaterial unit cells, that is, having both negative permittivity and permeability, which redirect negative refractive and also are not found in nature. The metamaterial is fabricated on magnesium zinc ferrite-based flexible microwave substrates, and the flexible substrates are chosen with two different concentrations of magnesium (Mg) denoted by Mg30 and Mg50 for 30% and 50% of Mg, which possess dielectric constants of 4.32 and 3.15 and loss tangents of 0.003 and 0.005, respectively. The proposed metamaterials are demonstrated by utilizing the CST microwave simulator, and their effective parameters are extracted according to the Nicolson-Ross-Wire method. With Mg30, the prepared, flexible metamaterial shows measured resonances at 3.70 GHz, 7 GHz, 8.60 GHz, and 9.78 GHz, whereas with Mg50 it shows the measured resonances at 4.10 GHz, 7.70 GHz, 9.33 GHz, and 10.62 GHz. Very good effective medium ratios (EMR) along with DNG properties are obtained, namely 6.5 and 5.85 for Mg30 and Mg50, respectively, with a physical dimension of 12.5 × 9.5 mm2 for both of the unit cells. Also, the electric field, magnetic field, and surface current distribution at different resonances and the polarization insensitivity at different polarization angles were observed. Thus, the designed new flexible substrate microwave materials based on DNG metamaterials are potential candidates for S-, C- and X-band applications, as well as for flexible microwave technologies.

Novel electromagnetic metamaterial: Polymer-derived SiCN(Fe) ceramics

The PDCs-SiCN(Fe) ceramics with negative permeability and permittivity (double-negative properties) were synthesized by polymer-derived method with ferric acetylacetonate as additive. The phase composition, microstructure, carbon crystalline state and electromagnetic properties of PDCs-SiCN(Fe) ceramics were analyzed. The results indicated that the double-negative properties of PDCs-SiCN(Fe) ceramics were controlled by the amount of Fe. The minimum reflectivity value (RLmin) of PDCs-SiCN(Fe) ceramics with 7 wt% Fe reached −54 dB in the double-negative frequency range (13.85–14.15 GHz) with 2 mm (thickness). In addition, the peak of the RLmin moved to the low frequency as the thickness increased, indicating the effective absorption band of PDCs-SiCN(Fe) ceramics can be broadened by adjusting the thickness.

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.

Menger fractal structure with negative refraction and sound tunnelling properties

We construct new quasi-three-dimensional fractal acoustic metamaterials based on adoption of the Menger structure, which offers extraordinary parameters such as double-negative properties and a near-zero density. The resulting metamaterials can thus achieve negative refraction, acoustic focusing and sound tunneling. Using the finite element method and the S-parameter retrieval method, the band structures and the effective parameters of these acoustic metamaterials are researched, respectively. The negative refraction property is numerically simulated using a Gaussian beam passing through a double negative prism. A plate lens with a refractive index of n = −1 is constructed to achieve acoustic focusing and the sound tunnelling ability is verified using the near-zero-density metamaterial. The results show that the Menger fractal structures have excellent acoustic properties and are promising for acoustic applications.

Hybrid rectennas of printed dipole type on Double Negative Dielectric Media for powering sensors via RF ambient energy harvesting

The harvesting of ambient RF power would be a promising respond to the requirement of continuous power support the sensors of wireless networks, without using batteries. The devices used for scavenging the RF power are known by the term rectennas and their first unit is an antenna which captures the power of impinging RF signals and then guide it to be rectified and stored by the rest of rectennas' grades. This article proposes an antenna scheme suitable for rectenna applications at the Universal Mobile Telecommunication System (UMTS), from 1.92 GHz to 2.17 GHz. The antenna is composed of planar dipoles with specific layout, printed on dielectric substrate with Double Negative (DNG) electromagnetic properties. The DNG substrate is composed of dielectric spherical particles that are hosted in a medium of very low dielectric constant and have suitable size in order to resonate at the UMTS band, thus developing high intensity electromagnetic fields. The dipoles embedded to this hybrid structure gather amounts of RF power larger than in case of an ordinary dielectric. Moreover, the antenna was synthesized with intend a matching network between it and the rectifier not to be used, thus avoiding potential losses and complexity. Considering that the rectenna will work in mobile telecommunication environment, where the incoming signals are of statistical nature, its performance was studied using its Mean Effective Gain (MEG), the Cross Polarization Power Ratio (XPR) and the Directions of Arrival (DoAs) of the incoming waves. Statistical mean values for DC voltages and power equal to 172 mV and 65 μW respectively and with mean efficiency 58% were obtained for incident power 0.2 mW, while, depending on case, the DC voltage may exceed the 300 mV and the power the 160 μW.

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

The mechanism of negative permittivity/permeability is still unclear in the random metamaterials, where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic. Here silver was introduced into porous SiO2 microsphere matrix by a self-assemble and template method to construct the random metamaterials. The distribution of silver was restricted among the interstices of SiO2 microspheres, which lead to the precise regulation of electrical percolation (from hoping to Drude-type conductivity) with increasing silver content. Negative permittivity came from the plasma-like behavior of silver network, and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response. During this process, the frequency of epsilon-near-zero (ENZ) could be adjusted accordingly. Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork. The calculation results indicated that negative permeability has a linear relation with ω0.5, showing a relaxation-type spectrum, different from the “magnetic plasma” of periodic metamaterials. Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials, with the advantage of enhanced absorption (40dB) and intelligent frequency selection even in a thin thickness (0.1 mm), could have potentials for electromagnetic attenuation and shielding. This work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials, as well as a novel strategy to precisely control the microstructure of random metamaterials.

Left-Handed Metamaterial-Inspired Unit Cell for S-Band Glucose Sensing Application.

This paper presents an oval-shaped sensor design for the measurement of glucose concentration in aqueous solution. This unit cell sensing device is inspired by metamaterial properties and is analytically described for better parametric study. The mechanism of the sensor is a sensing layer with varying permittivity placed between two nozzle-shaped microstrip lines. Glucose aqueous solutions were characterized considering the water dielectric constant, from 55 to 87, and were identified with a transmission coefficient at 3.914 GHz optimal frequency with double negative (DNG) metamaterial properties. Consequently, the sensitivity of the sensor was estimated at 0.037 GHz/(30 mg/dL) glucose solution. The design and analysis of this sensor was performed using the finite integration technique (FIT)-based Computer Simulation Technology (CST) microwave studio simulation software. Additionally, parametric analysis of the sensing characteristics was conducted using experimental verification for the justification. The performance of the proposed sensor demonstrates the potential application scope for glucose level identification in aqueous solutions regarding qualitative analysis.