Single Split Ring Research Articles

A Comprehensive Evaluation Method for Sensing Characteristics of Multi-Peak Terahertz Metamaterials Sensor in Polarization Mode

In this study, the multi-peak terahertz metamaterials sensors are designed and fabricated, whose structures are the asymmetrical single split ring (SSR) and three split rings (TSR). The resonant formation and sensing mechanism of the two structures are investigated by using the finite-difference time-domain (FDTD) method. Vitamin B6 (VB6) and its reactants with bovine serum protein (BSA) are tested as the medium, and the sensing experiments of the SSR and TSR are carried out. The experimental and simulation results indicate the consistent law, which is the sensitivity of the resonance in the transverse magnetic (TM) mode is much greater than that in the transverse electric (TE) mode. According to the weighted average method and the law for unequal precision measuring, the quality factor of the resonance is used as the weighting coefficient to calculate the comprehensive evaluation parameter (CEP) of the multi-peak metamaterials sensors in the TE and TM modes based on the experimental data. When the CEP and frequency shifts are as the evaluation parameter in experiments, the law’s variation of the CEP is consistent with that of the frequency shift, indicating that it is feasible to characterize the sensing characteristics of metamaterials with the CEP, which presents simplified characteristics of multi-peak metamaterials at different polarization modes. The method implies that the different influencing factors may be integrated into the CEP with the idea of weight, which promotes the practical application of the metamaterials sensor. The revelation of the sensing law also provides a method for the design of the terahertz metamaterials sensor with the high sensitivity.

Graphene-Based Metasurface Refractive Index Biosensor for Hemoglobin Detection: Machine Learning Assisted Optimization.

Machine learning is the latest approach to optimize the performance of absorbers, sensors, etc. A sensor with behavior prediction using polynomial regression is presented. Three different variations of metasurfaces namely double split-ring resonator, single split ring resonator, split ring resonator with thin wire are analyzed. The proposed design aims to achieve the highest sensitivity by observing different designs and different parameter variation. The highest sensitivity is achieved for double split-ring resonator and single split ring resonator designs. The change in thickness of different parameter affect the absorption and the highest sensitivity is calculated based on these variations. The polynomial regression (PR) model is employed to predict the absorption values for assorted combinations of intermediate wavelength values with angle variation, substrate thickness, substrate length, substrate width, graphene potential, and resonator thickness values. Test Cases R-30 and R-50 are evaluated using R2 score metric to assess the effectiveness of PR model for predicting the values of absorption. R2 score close to 1.0 is achieved for all the experiments at a higher (more than 5) polynomial degree, which proves the prediction efficiency of a regression model. The proposed biosensor designed with a PR model can be applied in biomedical applications for hemoglobin detection.

Improved circuit model for plasmonic resonance of single split-ring resonators

In this work, an improved circuit model is presented for the single split ring resonator (SRR), taking into account non-uniform distribution of conduction current and surface charges. To determine the circuit elements of the SRR, the electron kinetic, electric, and magnetic energy have been derived theoretically. Moreover, in addition to gap and surface capacitances, coupling capacitance is introduced to characterize the electric coupling effect between them. A formula for the fundamental resonance wavelength has been obtained, which shows good agreement with numerical simulations in both optical and microwave frequency ranges. The model will be instructive for engineering resonant properties of the SRRs and provide valuable insight into other complex plasmonic structures.

Gain Enhancement of Patch Antenna Using High Refractive Index Metamaterial-based Bi-convex Lens for Base Station Applications

ABSTRACT In this paper, a high refractive index-based metamaterial Bi-convex lens superstrate for the gain enhancement of broadside radiating antennas like microstrip antennas is presented. Fundamentally, an effective HRI medium is created by the Single Ring Split Ring Resonator unit cells printed on an FR-4. By stacking the multiple layers of the superstrate, a virtual HRI-based equivalent Bi-convex lens is constructed to focus the incoming diverged beam from a patch antenna. A gain enhancement of 4.42 dB is achieved with the help of a 3-layer HRI-based Lens superstrate. The simulation and measurement results are also almost agreed on the same.

Compact microwave sensor for monitoring aging of oil and fuel adulteration

Adulteration detection of liquids is an emerging field in the present scenario. Purity detection of engine oils and fuels is essential for the smooth functioning of automobiles. An asymmetric coplanar strip fed stepped impedance resonator (SIR) coupled single split ring resonator (SSRR) sensor is used for purity and adulteration detection of engine oil and fuels in automobiles. The sensor operating at 5.95 GHz in free space on a low-cost substrate with a compact size of 10 × 11.5 × 1.6 mm3 is demonstrated in this article. The impedance contrast between the two lines of SIR and the coupled SSRR improves the electric field distribution and thus the sensitivity. The resonant frequency of the proposed sensor changes with the aging of the oil or the adulteration level. The sensor performance is analyzed with simulations and validated with measurements.

Modeling of a Negative Refractive Index Metamaterial Unit-Cell and Array for Aircraft Surveillance Applications

In this paper, a unique negative refractive index-metamaterial (NRI-MTM) structure is proposed for traffic alert and collision avoidance system (TCAS) for aircraft application. The NRI-MTM unit-cell structure is a combination of square and circular split ring structures. The proposed square and circular split ring metamaterial (SCM) is designed on the top of a 1.6 mm thick FR-4 substrate, with a single circular split ring on the bottom of the substrate. The total dimension of the SCM unit-cell is 23 × 23mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.08λ × 0.08 λ), resonating at 1.06 GHz. This unit-cell is further used to create a 5×4 array structure with a dimension of 130 × 111mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.46 λ × 0.4 λ). A High-Frequency Structure Simulator (HFSS) is used to assess the electromagnetic properties of the proposed structures. Furthermore, in order to analyse the double negative (DNG) behaviour of the designed SCM structure, the unit-cell is rotated from 0 to 360 degrees with a step of 60 degrees along the azimuthal plane. On doing so, it is observed that, the proposed SCM structures, including unit-cell and array structures, exhibit DNG and NRI properties over the frequency band of 0.5 to 1.2 GHz, thus making it optimum for aircraft surveillance application. The SCM unit-cell and 5 × 4 SCM array structure were fabricated, and the measured results are in well agreement with the simulated results. Further, the array structure is used as a superstrate on the patch antenna to analyze the impact of the MTM on the antenna performance. In comparison to the antenna without the MTM structure, the 5 × 4 SCM array loaded antenna has a gain improvement of 2.8dB and a bandwidth enhancement of 31.5MHz.

Bandwidth Enhancement of Circular Ring Patch by Loading Single Split Complementary Split Ring Resonator

Metamaterials have gained a lot of interest in modern wireless devices due to their electromagnetic characteristics and it is employed to improve antenna parameters such as bandwidth, gain and efficiency. The study presents a novel strategy of single split non-uniform width Complementary Split Ring Resonator (CSRR) equipped Circular ring Microstrip Antenna (CRMA). The radiating element dimensions are seen to be 20 mm x 20 mm at the initial working frequency wherein the CSRR is incorporated on the ground plane of CRMA. The single split non-uniform width metamaterial (CSRR) structure displays -10 dB impedance bandwidth at 11.1 and 13.56 GHz which is beneficial for applications pertaining to X and Ku band. The total bandwidth of the said metamaterial antenna is 4 GHz (10.73-14.75). Optimization is undertaken with the help of commercially assessable simulation software tool Ansys HFSS 2019 version and practically measured using network analyzer. It is quite obvious from the experimentation that the results calculated get along well with the assumed outcomes.

Metamaterial Circularly Polarized Antennas: Integrating an epsilon negative transmission line and single split ring-type resonator

This article discusses the future possibilities and analysis of metamaterial (MTM)-based compact circularly polarized (CP) antennas for wireless applications. Here an effective method is introduced for designing a simple and efficient MTM CP antennas by integrating with an epsilon negative (ENG) transmission line (TL) and single split ring (SSR)-type resonator. For improving the radiation characteristics, a compact size artificial magnetic conductor metasurface (AMC-MS) without via is loaded with the intended ENG TL-based radiator antenna as a ground plane. The novelty of this kind of ENG TL-based CP antenna with AMC-MS is discussed for the first time in the literature and further image theory concept is applied for finding the driving point impedance. This kind of design is suitable for all frequencies by proper optimization and scaling. The radiating element of the intended antenna acquires a smaller area due to its zeroth-order resonance (ZOR) property with dimension of 0.26 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz with an overall dimension with AMC-MS are 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz. The measured results of the antenna show an impedance bandwidth of 16.36% and a CP bandwidth of 11.93%. The antenna shows a gain of 5.62 dBic and average radiation efficiency of 72.1% along the frequency band.

Research Advance on the Sensing Characteristics of Refractive Index Sensors Based on Electromagnetic Metamaterials

Among different sensing platforms, metamaterials composed of subwavelength or deep subwavelength sized metal resonance elements arrays that are etched on semiconductor substrates or dielectric substrates exhibit excellent characteristics due to the strong localization and enhancement of resonance electromagnetic fields. As a new type of detection method, metamaterial sensors can break through the resolution limit of traditional sensors for a small amount of substance and have the advantages of high sensitivity, fast response, and simple measurement. Significant enhancement of the sensing characteristics of metamaterial sensors was realized by optimizing microstructures (single split-ring, double split-ring, nested split-ring, asymmetric split-ring, three-dimensional split-ring, etc.), using ultrathin substrates or low-index substrate materials, etching away local substrate, and integrating microfluidic channel, etc. This paper mainly reviews the research advance on the improvement of sensing characteristics from optimizing resonance structures and changing substrate materials and morphology. Furthermore, the sensing mechanism and main characteristic parameters of metamaterial sensors are introduced in detail, and the development trend and challenge of metamaterial sensing applications are prospected. It is believed that metamaterial sensors will have potential broader application prospects in environmental monitoring, food safety control, and biosensing in the future.

Graphene-Based Plasmonic Absorber for Biosensing Applications Using Gold Split Ring Resonator Metasurfaces

We propose a novel graphene-based metasurface plasmonic biosensor. The gold split-ring resonator is used as a metasurface element in the biosensor. Split Ring Resonator structures are used to localize and increase electromagnetic field incidents. Two types of split-ring resonator based metasurface (Single split-ring resonator and Double split-ring resonator) designs are analyzed to observe its effect on biosensing. The proposed biosensor is used to sense hemoglobin and urine biomolecules for their different concentrations. The design results in the form of absorption, electric field, and magnetic field are presented. The sensitivity for hemoglobin biomolecules and urine biomolecules are calculated from their absorption peak difference and refractive index difference. The sensitivity results are compared with previously published designs. The proposed single split ring resonator metasurface design has the highest sensitivity for hemoglobin-urine concentrations. The proposed biosensor can become a building block for future medical biosensing devices.

Flexible leather substrate dual-band wearable antenna with impact analysis on testing under wet condition for human rescue system

Wearable flexible antennas have yielded much attention in recent years because of their interesting features and capabilities for enabling flexible, lightweight, portable and low cost wireless communication. The proposed research work offers the design of the flexible wearable patch antenna with four single Split Ring Resonators (SRRs) using a leather substrate for better performance. The proposed antenna is designed and simulated with leather substrate at the operating frequencies of 0.99 GHz and 3.5 GHz. The antenna is fabricated and validated under free space (normal condition), partially wet, fully wet and dried after wet conditions using Vector Network Analyzer (VNA). Different parameters such as reflection coefficient, Voltage Standing Wave Ratio (VSWR) and gain of the fabricated antenna are measured, and they are compared with the simulation results. The validated results show that the performance of the proposed antenna under free space, partially wet, fully wet and dried after wet conditions is virtually equal. The Specific Absorption Rate (SAR) of this proposed antenna is also investigated for 10g tissues and the SARs are 0.0168763 W/kg and 0.69567 W/kg at the operating frequencies of 0.99 GHz and 3.5 GHz, respectively. As a result, its good performance in wet conditions along with low cost and ready availability of leather material means the proposed antenna can be used for human safety environments, especially in military applications, etc.

Resonant Characteristics of Split Ring Resonator and Unit Cell for Periodic Metamaterial Devices

The resonant characteristics of single split ring resonator-based metamaterial devices with single gap are presented using the analytical formulation developed for the lumped element equivalent circuit model. The characteristics of the metamaterial resonators have been investigated for different ring sizes, gap widths and substrate permittivity. Equivalent circuit model is developed for two ring structures. The analytical, and simulation results are compared and verified. The prototype has been then built and measured. It has been observed that all the results agree. The results presented in this paper can be used to develop devices at the THz range that can operate as sensors, antennas or tuning elements.

Metamaterial-based sensor design using split ring resonator and Hilbert fractal for biomedical application

In this work, a novel approach is presented to design a metamaterial-based sensitive sensor for biomedical applications. The metamaterial-based sensor objective is to differentiate between different types of cancer cell lines (biological cells) based on their electrical properties. The sensor is designed by incorporating a single circular split ring resonator (SRR) and a Hilbert fractal curve. The SRR is designed based on its capacitive and inductive resonance properties, thereby making the SRR a favorable candidate for sensing applications. Moreover, the Hilbert fractal curve is introduced as a defected ground structure to move the resonance frequency of the SSR to lower band, and to increase sensor sensitivity. Different Hilbert curve orders are investigated. The fourth-order Hilbert curve is used in the final design as it showed the optimal performance among other orders. To verify the sensor functionality and selectivity, the proposed sensor is tested on three types of breast cancer cell lines, these are MCF7, MCF-7, and HS578T. Measurement results of the fabricated sensor compared well with simulated results obtained using high-frequency structure simulator (HFSS18).

Planar suspended line technique based UWB-MIMO antenna having dual-band notching characteristics

AbstractThis communication reports significant isolation improvement utilizing planar suspended line (PSL) technique in ultra wideband (UWB) antenna for Multiple Input Multiple Output (MIMO) application. The antenna exhibits dual-band notched characteristic in Wireless Local Area Network (WLAN) band covering 5.45–5.85 GHz range; and in 7.15–7.95 GHz range for X-band downlink operations in satellite communication. Band-notching characteristics have been obtained by employing a single Elliptical Split Ring Resonator (ESSR) placed adjacent to each microstrip feed line of the radiating element and duo of “Y”-shaped strips employed within the circular ring of individual radiating elements. Two elements antenna occupy a compact space of 20 × 36 × 1.6 mm3 exhibiting huge measured impedance bandwidth (S11/S22 &lt; −10 dB) covering 3.1–11.5 GHz and significant isolation of &gt;21 dB in the almost entire band of operation. The electrical performance of antennas has been analyzed in terms of various MIMO parameters. Measured results demonstrate good accord with simulated results proving the competency of proposed antenna in high-density package systems and massive MIMO applications.

Ultra-Wideband Metamaterial-Loaded Microstrip Array Antennas using Fibonacci &amp; Fractal Geometric Patterns, Design and Modelling

In this study; theory, design and modeling of a new topology of ultra-wideband (UWB) metamaterial (MTM) loaded microstrip array antenna using Fibonacci &amp; fractal geometric patterns are analyzed. This antenna is made basically from many monopole elements which are loaded by complementary metamaterial transmission line (CMTL) unit cells. The distributed CMTL element, contains a Koch-shaped expanded complementary single split ring resonator (CSRR) pair. At first step, the UWB microstrip array antenna designed with two CMTL-loaded monopole element. So, using an iterative method based on the Fibonacci and fractal geometry patterns, the array antenna is expanded. As the order of iteration increases, the impedance bandwidth of the proposed array antennas improve more, and the radar cross section (RCS) decreases. the impedance bandwidth of the proposed third-order Fibonacci and fractal CMTL-loaded array antennas are 250 MHz and 539 MHz more than the two-element CMTL-loaded array antenna, respectively. Finally, this paper presents an improved method to extract the parameters of an equivalent circuit model of the proposed MTM-loaded array antenna. Verification of the equivalent model have been validated utilizing ADS software. The obtained model, in addition to numerically efficient in comparison with the full wave analysis utilizing the moment method, gives a good physical insight to the mutual coupling mechanism of the array antenna.

CSRR Based Sensors for Relative Permittivity Measurement With Improved and Uniform Sensitivity Throughout [0.9–10.9] GHz Band

This paper proposes miniaturized, lightweight and high sensitivity planar metamaterial based sensors for relative permittivity measurement within [0.9–10.9] GHz band. Each proposed sensor is designed using a thin-substrate microstrip line loaded with a single complementary split ring resonator (CSRR). The loaded resonator is excited using maximum electric/magnetic (cross polarization) excitation to maximize the sensors’ sensitivity. Each proposed sensor operates at different frequency range within [0.9–10.9] GHz band based on the size of the loaded resonator. Compared to similar state-of-the-art sensors, the proposed ones are at least 30% more sensitive. The minimum transmission frequency shifts (50)% as the sample’s relative permittivity changes from 1 to 10. The paper proposes a condition of sensitivity uniformity to maintain a uniform sensitivity over the specified band irrespective of the resonator size. Utilizing the proposed condition, the sensitivity of all sensors remains uniform throughout [0.9–10.9] GHz band for all dielectric samples with relative permittivity between 1 and 10. This vital feature allows the practical realization of resonant probes with less computational operations and consistent measurements over a wide dynamic range of the sensing-related frequency. Experimental measurements are in good agreement with the numerical findings. The paper includes a comprehensive sensitivity analysis which investigates the effect of resonator’s excitation scheme, resonator’s order (i.e. single or double CSRR) and substrate thickness on the sensitivity of CSRR based sensors. The proposed sensing platforms are recommended for the development of highly sensitive, consistent and reliable planar sensors such as microfluidics, displacement, nondestructive and biomedical sensors.

Numerical study of a broadband metamaterial absorber using a single split circle ring and lumped resistors for X-band applications

We report a numerical study on the design of a broadband metamaterial absorber (MMA) with a single layer of metal–dielectric–metal based on an FR-4 substrate for X-band applications. The MMA structure consists of a periodic array of a split circle ring and lumped resistors coupled within split segments. The MMA structure achieves a broadband absorption response in the frequency range of 7.8–12.6 GHz with an absorptivity of above 90% under normal incidence for all polarization angles. The absorptivity remains above 70% in the frequency range of 6.8–11.8 GHz at wide incident angles from 0° to 30° for both transverse electric and transverse magnetic polarizations. The physical mechanism of the absorber is explained by the electric and the surface current distributions that, in turn, are significantly affected by magnetic resonance.

Design of circularly polarized patch antennas using anisotropic high refractive index metamaterial loading

ABSTRACTIn this paper, for the first time, the development of the circularly polarized square-shaped patch antenna is performed with the assistance of anisotropic high refractive index (HRI) metamaterial. The HRI metamaterial is realized with the help of an investigation conducted on the single ring split ring resonator (SR-SRR). With the benefit of the concept of duality, the complementary SR-SRR is considered to load on to ground plane (instead of SR-SRR) to function as an effective HRI medium. The concept of the High refractive index in slowing down the waves is explained quantitatively. The anisotropy of the effective HRI metamaterial medium is used to create the phase difference between the orthogonal components. Anisotropy of the unit cell was used to realize one RHCP and one LHCP antenna from the same fundamental design by just rotating the unit cell. For both antennas, the simulated and measured results are agreed on the same.

Miniaturization of monopole antenna using high refractive index metamaterial loading

In this article, miniaturization of the wire monopole antenna with the help of high refractive index (HRI) metamaterial is presented. For the first time, HRI medium is realized by using the array of single ring split ring resonator. By surrounding the wire monopole with the array of SR-SRRs, the effective wavelength is squeezed in the vicinity of the near field dominance. By the loading of the monopole with such an HRI medium, the size of the antenna is reduced from 29.5 to 16 mm, without any deformation in the current distribution and radiation pattern corresponding to the fundamental resonance. The simulated and measured results are agreed to the same.

Design of Ultra-Wideband Tapered Slot Patch Antenna with Reconfigurable Dual Band-Notches

This paper presents an ultra-wideband tapered slot patch antenna with bi-directional radiation, reconfigurable for dual band-notched capability and fed by coplanar waveguide. The proposed antenna showed excellent ultra-wideband characteristics with bandwidth of (1.9–12 GHz). In order to reduce the interference of the narrow band communications represented by Worldwide Interoperability for Microwave Access radiation in the range (3.4–3.9) GHz and standard IEEE 802.11a. application (from 5.1 GHz to 6.1 GHz), the antenna was accompanied with adjustable dual-stop band capability in these bands. The dual-band notches are achieved with aid of inserting a parasitic single split ring resonator and etching a single circular complementary circle split ring resonator. The proposed antenna used epoxy (FR4) substrate material with ????r= 4.4 and dimensions of .