Double Split Ring Resonator Research Articles

Coplanar Stripline Coupled to Planar Double Split-Ring Resonators for Bandstop Filters

Double split-ring resonators (SRRs) have previously been used with coplanar waveguide and microstrip to build bandstop filters (BSFs). This letter for the first time demonstrates SRRs coupled to coplanar stripline (CPS) to demonstrate their use as a BSF. The SRRs are on the same plane as the CPS lines. It is further shown that the orientation (the gap in the ring near the CPS line or on the opposite side from the CPS line) of the SRR affects the resonant frequency and the level of rejection, which is not predicted in the earlier papers.

Tunable terahertz metamaterial by using three-dimensional double split-ring resonators

We present an optically tunable terahertz (THz) metamaterial by using three-dimensional double split-ring resonators (3D-DSRR), which shows superior properties in adjustability. They exhibit tunable single-band and dual-band resonances by changing height between inner and outer SRRs. The maximum tuning range of dual-band resonance is 0.55 THz from the resonance of 0.45 THz shifted to the resonance of 1.00 THz. The corresponding tuning range of free spectrum range (FSR) spanned two resonances can be tuned from 0.20 THz to 0.75 THz. By changing radius of inner SRR from 14.5 μm to 22.5 μm, the tuning range of resonance is 0.40 THz. While changing the height between inner and outer SRRs and kept the radiuses of inner and outer SRRs as constant as 22.5 μm, 3D-DSRR can be tuned to have two resonances and then merge into one resonance. 3D-DSRR shows a tunable and switchable resonance for single-band and dual-band characteristics. These characterizations are very suitable for the use of tunable multi-resonance applications. To further investigate the stability of 3D-DSRR, the rotation angles of inner and outer SRRs are modified from 0° to 180°, respectively. The corresponding resonances are identical. Such results indicate the proposed device with high stability to allow manufacturing tolerance and potentially to be used in wearable electronic devices, pressure sensors, and other fields.

Temperature-dependent tunable terahertz metamaterial absorber for the application of light modulator

Abstract A temperature-dependent tunable metamaterial absorber (MA) based on strontium titanate (STO) is proposed at terahertz regions. The MA is a three-layer structure, which is composed of double metallic split-ring resonators (SRRs), silicon substrate, and the ground metallic layer. Numerical results show that the single-band high absorption with the coefficient of 99% is achieved at the frequency of 1.23 THz, and the position of resonant frequency is blue-shifted by increasing the ambient temperature to control the relative permittivity of STO material, which is embedded into two slits of SRR. Moreover, it is found that the absorption efficiency of MA can be tuned by changing the conductivity of vanadium dioxide (VO2) through ambient temperature. Considering the limitation of single-band absorption, a simple method is proposed to achieve dual-band high absorption by rotating the top SRR layer at different angles α. The two high absorption efficiencies of 100% and 97% at the frequency of 1.28 THz and 1.43 THz, respectively, can be obtained when α = 45°. The proposed MA can be used in some areas in term of sensors, light modulators and terahertz absorbers.

Dynamics Analysis of a Pair of Ring Resonators in Liquid Media

Usually we discuss a metamaterial in terms of just its optical behavior on a solid substrate in air. What about the behavior of a metamaterial operating in a viscous low-loss liquid? This study uses the theories of classical electromagnetism and fluid dynamics to solve for the coupling between the electromagnetic force and the liquid-resistance force, and the resulting dynamics of a double split-ring resonator (a common form of meta-atom in a complete metamaterial). Experiments match the predictions well. These results help to guide and extend our consideration of metamaterials to applications in liquid environments.

Multi-Band Sensing for Dielectric Property of Chemicals Using Metamaterial Integrated Microfluidic Sensor

The growth of the chemical industry has brought tremendous challenges to chemical sensing technology. Chemical sensors based on metamaterials have great potential because of their label-free and non-destructive characteristics. However, metamaterials applied in chemical sensing have mainly been investigated from the measurement of sample concentration or the determination of the dielectric properties at a fixed frequency. Here we present a metamaterial integrated microfluidic (MIM) sensor for the multi-band sensing for dielectric property of chemicals, which is promising for the identification of chemicals. The MIM sensor mainly consists of multiple pair of high sensitive symmetrical double split-ring resonators (DSRRs) and meandering microfluidic channels with a capacity of only 4 μL. A dielectric model has been innovatively established and experimentally verified to accurately estimate the complex permittivity and thus realize the multi-band sensing of dielectric property of chemicals. With the increase in the number of resonators in the sensor, a dielectric spectrum like curve could be obtained for more detailed dielectric information. This work delivers a miniaturized, reusable, label-free and non-destructive metamaterial-microfluidic solution and paves a way of the multi-band sensing for dielectric property of chemicals.

A compact dual-band bandpass SIW filter using uniplanar combination of the CRLH and resonant type metamaterials

ABSTRACTA new manner of obtaining dual bandpass behaviour in substrate-integrated waveguide (SIW) using a uniplanar combination of composite right/left-handed (CRLH) transmission line and complimentary double split single ring resonator (CDSSRR) is presented and analysed in this paper. The proposed dual band structure has the advantage of miniaturisation due to the presence of both the passbands below the characteristic cutoff frequency of the SIW.A high passband transmission zero overcomes the poor frequency selectivity, and the two resonant frequencies are independently controllable. There are very low insertion losses in both passbands as compared to DGS structures and fabrication simplicity is ensured due to an intact ground. The potential for application of the proposed structure to the design of completely planar miniaturised dual band bandpass metamaterial filters has been verified by fabricating a two-stage filter based on the proposed combination. The measured results are in good agreement with the simulation results.

Tunable terahertz metamaterial by using asymmetrical double split-ring resonators (ADSRRs)

Two designs of asymmetrical double split-ring resonators (ADSRRs) with one layer and two reflective symmetric layers are presented, which are composed of Au material on Si substrate. The electromagnetic responses of ADSRRs designs exhibit a single-resonance for g = 0 μm and dual-resonance in the range of g = 2 μm to 10 μm. By changing the gap width of ADSRRs with one layer, the resonant frequencies of two devices are blue-shifted 0.11 THz from 0.67 THz to 0.78 THz at TE mode and blue-shifted 0.07 THz from 0.62 THz to 0.69 THz at TM mode. To improve and perform the active tuning of ADSRRs, two devices are designed to compose of two reflective symmetric layers with a distance between top and bottom ADSRRs. By changing this distance, the tuning range of resonance is enhanced to 0.52 THz. Furthermore, two devices with one layer and two reflective symmetric layers exhibit a switch behavior by changing incident polarization angle. The maximum modulation depth is up to 93%. Therefore, the resonant frequency of devices can be tuned by changing the distance between top and bottom reflective symmetric ADSRRs to be realized as a THz filter and by changing the incident polarization angle to be realized as a THz switch. This study promises applications in THz filters, THz switches, and other controllable metamaterial-based devices.

Independently tunable dual-spectral electromagnetically induced transparency in a terahertz metal–graphene metamaterial

We theoretically investigate the interaction between the conductive graphene layer with the dual-spectral electromagnetically induced transparency (EIT) metamaterial and achieve independent amplitude modulation of the transmission peaks in the terahertz (THz) regime. The dual-spectral EIT resonance results from the strong near field coupling effects between the bright cut wire resonator in the middle and two dark double-split ring resonators on the two sides. By integrating monolayer graphene under the dark mode resonators, the two transmission peaks of the EIT resonance can exhibit independent amplitude modulation via the shifting of the Fermi level of the corresponding graphene layer. The physical mechanism of the modulation can be attributed to the variation of damping factors of the dark mode resonators arising from the tunable conductivity of graphene. This work shows great prospects in designing multiple-spectral THz functional devices with highly flexible tunability and implies promising applications in multi-channel selective switching, modulation and slow light.

A Novel Metamaterial Inspired High-Temperature Microwave Sensor in Harsh Environments.

A high-temperature sensor based on a metamaterial unit cell is proposed in this paper. The wireless passive temperature sensing method is based on the electromagnetic backscatter principle, and thus has the advantages of higher quality, lower environmental interference, and anti-low frequency interference. We developed a finite-element method-based model for the sensor via high-frequency simulation software (HFSS). A double split-ring resonator (SRR) with an outer ring length of 13 mm was designed on alumina ceramic substrate. The sensor was fabricated at 2.42 GHz using micromechanical technology and screen printing technology. When the temperature increased from 28 to 1100 °C, the resonant frequency decreased from 2.417 to 2.320 GHz with an average sensitivity of 95.63 kHz/°C. As the sensor is easily designed and fabricated, it can be used for chipless radio frequency identification (RFID) tags by simply changing the size of rings. Furthermore, emerging 3D printing technology and commercial desktop inkjet printers will be used to realize the rapid low-cost preparation of the sensor, enabling its wide range of applications in aerospace, military, manufacturing, transportation, and other fields.

Double-split labyrinth resonator with defective ground system for wide-band band-stop filter application

A labyrinth resonator with defective ground structure (DGS) is introduced for designing a wide-band band-stop filter in order to adjust the resonating characteristics by varying the dimension of the structure to cover 2.75 – 10.30 GHz. A series of modified double-split ring resonators (DSRRs) are embedded into a 50Ω microstrip framework to attain a labyrinth structure. The Rogers RO- 3010, which has a succinct structure, is used as the substrate in the proposed wide-band band-stop filter. The realization of the architecture is explored both integrally and experimentally, and a complementary split ring resonator (CSRR) is introduced in the ground layer. The level of rejection of the filter in the stop-band region increases with the introduction of the CSRR. In addition, the filter is evaluated by applying the Nicolson-Ross-Weir approach at the filtering frequency. The effective electromagnetic parameters retrieved from the simulation of the S-parameters imply that the metamaterial structure exhibits negative refraction bands. With a promising design and wide range of double-negative characteristics, we propose a new type of filter which is suitable for a wide-band band-stop application.

Design of Miniaturized Multiband Patch Antenna Using CSRR for WLAN/WiMAX Applications

A novel miniaturized multiband, single-feed microstrip patch antenna is presented in this paper for WLAN and WiMAX applications. Both size reduction and multiband are obtained by etching the Multiple Complementary Split Ring Resonators (MC-SRR) on the ground plane of the normal patch antenna. At first, the normal patch antenna produces a single band of 5.15 GHz; 200 MHz (5.0500~5.2499). Subsequently, a Single Circular Split Ring Resonator (SC-SRR) is etched on the ground plane and produces a triple band of: 3.25 GHz; 288 MHz (3.1085~3.3964), 4.5 GHz; 101.3 MHz (4.4488~4.5501), and 5.22 GHz; 220 MHz (5.1191~5.3400) and Double Single Circular Split Ring Resonator (DC-MCSRR) with: 2.99 GHz; 60.7 MHz (2.9574~3.0181), 3.57 GHz; 324.7 MHz (3.4065~3.7312), and 5.1413 GHz; 115.4 MHz (5.0817~5.1971). The working bandwidths cover the desired frequency bands of WLAN 5.2 GHz and WiMAX 3.3/3.5 GHz. The proposed (MC-SRR) antenna can be employed to wireless communication systems due to its simplicity in design, compactness and miniaturization.

Periodic Arrays of Magnetoelectrically Excited Double and Single Split-Ring Resonators as Artificial Magnetic Conductors

The amplitude and phase of the reflection coefficient of periodic arrays of electrically conducting elements in the form of double and single split rings are determined for two orientations of these rings, corresponding to magnetic (H) and magnetoelectric (HE) excitation. It is shown that, in the case of the HE-excitation of the rings, the arrays possess the properties of an artificial magnetic conductor or a high-impedance surface. The electric and magnetic fields near the arrays are calculated, and the dependence of the impedance on the distance between the array and the plane in which the impedance is determined is obtained. It is shown that the maximum of the impedance is in close vicinity of the array and can amount to tens of thousands of ohms. The feasibility of implementing a modified Salisbury radio absorber of small thickness by means of such arrays is shown theoretically and experimentally. It is also shown that, under illumination of an array of limited dimensions by a closely placed dipole, the screening effect reaches –30 dB with good matching of the dipole to the feed line (the reflection coefficient in the line is less than –20 dB).

A Microwave Method for Dielectric Characterization Measurement of Small Liquids Using a Metamaterial-Based Sensor.

We present a microwave method for the dielectric characterization of small liquids based on a metamaterial-based sensor The proposed sensor consists of a micro-strip line and a double split-ring resonator (SRR). A large electric field is observed on the two splits of the double SRRs at the resonance frequency (1.9 GHz). The dielectric property data of the samples under test (SUTs) were obtained with two measurements. One is with the sensor loaded with the reference liquid (REF) and the other is with the sensor loaded with the SUTs. Additionally, the principle of extracting permittivity from measured changes of resonance characteristics changes of the sensor loaded with REF and SUTs is given. Some measurements were carried out at 1.9 GHz, and the calculated results of methanol–water mixtures with different molar fractions agree well with the time-domain reflectometry method. Moreover, the proposed sensor is compact and highly sensitive for use of sub-wavelength resonance. In comparison with literature data, relative errors are less than 3% for the real parts and 2% for the imaginary parts of complex permittivity.

Analyzing the effect of geometric parameters of double split ring resonator on the effective permeability and designing a cloak of invisibility in microwave regime

A metamaterial unit cell based on double split ring resonator has been designed. The SRRs consist of a pair of concentric square copper rings. The metamaterial unit cell designed in millimeter scales. Effect of some geometric parameters of the split ring resonator such as the size of the gap, the width of the split ring resonator copper wires, the length of the inner ring and the length of the outer ring on the magnetic permeability has been investigated. The magnetic resonance frequency, the magnetic plasma frequency, the resonance bandwidth and the effective magnetic permeability at 9.5 GHz related to each metamaterial unit cell with specified geometric parameters has been calculated. Using these metamaterial unit cells, an invisible cloak operating in microwave regime is designed. The situation of the gaps in the double split ring resonator with two and four gaps is also changed and the effective permeability for each of them is obtained.

Wideband printed monopole antenna for application in wireless communication systems

Empirical results of an electrically small printed monopole antenna are described with a fractional bandwidth of 185% (115 MHz to 2.90 GHz) for return-loss better than 10 dB, peak gain and radiation efficiency at 1.45 GHz of 2.35 dBi and 78.8%, respectively. The antenna geometry can be approximated to a back-to-back triangular shaped patch structure that is excited through a common feed-line with a meander-line T-shape divider. The truncated ground-plane includes a central stub located underneath the feed-line. The impedance bandwidth of the antenna is enhanced with the inclusion of meander-line slots in the patch and four double split-ring resonators on the underside of the radiating patches. The antenna radiates approximately omni-directionally to provide coverage over a large part of very high frequency, the whole of ultrahigh frequency, the whole of L-band and some parts of S-band. The antenna has dimensions of 48.32 × 43.72 × 0.8 mm 3 , which is corresponding to the electrical size of 0.235 λ 0 × 0.211 λ 0 × 0.003 λ 0 , where λ 0 is the free-space wavelength at 1.45 GHz. The proposed low-profile low-cost antenna is suitable for application in wideband wireless communications systems.

Specificities of the Microwave Reflection Coefficients of Magnetically Excited Chiral and Ring Conductive Elements for Separation of Magnetic and Electric Responses and Broadband Matching of Radio Absorbing Composites

Distinctive features of the resonance responses of the reflection of microwaves from conducting double and single split-ring resonators, making it possible to distinguish between the magnetic and electric responses and identify the magnetic response of elements of different shapes, are studied experimentally in a rectangular waveguide and numerically in free space. It is shown that the specificities of the frequency dependence of the magnetic response can be used for broadband matching of radio absorbing composites.

A Planar UWB Antenna with Dual Band Rejection Capability Using Double Rotated ESRRs

In this paper, CPW-Fed ultra wideband (UWB) planar monopole antenna (PMA) loaded by double elliptical split ring resonators (ESRRs) for double band-notch characteristics is introduced and examined. Two different ESRRs with different dimensions are printed in the antenna backside to notch two different frequencies. The ESRRs are also rotated and the corresponding return loss effect is examined. Different notch frequencies can be obtained by varying the ESRRs, dimensions. Two single SRRs are used to notch two frequencies instead of using dual SRR pairs. Two notch frequencies at 5.2 GHz and 6.9 GHz has been obtained to notch WLAN and C-band wireless applications, respectively. A directive radiation pattern in E-plane and omnidirectional radiation patterns in the H-plane could be observed. Also the gain is suppressed in the notch frequencies. The group delay is nearly stable in the UWB frequency range, except at the notch frequencies, which is distorted sharply. So, the proposed antenna is a good candidate for the modern UWB systems. Finite element method FEM and finite integration technique FIT are used to simulate the proposed structures through the usage of Ansys HFSS and CST MWS. Very good agreement between both results has been obtained.

A Novel Tunable Dual-band Left-Handed Metamaterial

In this paper, we propose a novel tunable left-handed metamaterial (LHM), the capacitor-loaded short wire pairs (CL-SWPs). It is composed of a pair of short wires connected through a variable capacitor. This LHM is single-sided, and it exhibits not only tunable negative permeability, but also a wide band negative permittivity. It is pointed out with theoretical analysis that its left-handed performance is related to the mutual coupling coefficient. A tunable dual-band LHM is also proposed by simply adding a double slits split ring resonator to this LHM. The simulated results indicate that the closer the two LH bands are, the better performance the CLSWP related left-handed band is, hence identifying our theoretical analysis. The proposed structure is geometrically simple, low-cost and easy for fabrication, and it can be used as a basic particle in the design of tunable multi-band LHMs.

Multiple magnetic resonance and microwave absorption of metamaterial absorbers composed of double split ring resonators on grounded carbonyl iron composites

This study investigates the triple-band absorption properties of metamaterial absorbers composed of a double split ring resonator (DSRR) on a grounded magnetic substrate of carbonyl iron powders. Computational tools are used to model the interaction between electromagnetic waves and the metamaterial structure. For perpendicular polarization with the electric field perpendicular to the SRR gap, triple-band absorption peaks are predicted in the simulation result of reflection loss. Magnetic resonance resulting from antiparallel currents between the upper DSRR and the lower ground plane is identified at the frequencies of the absorption peaks. The orientation of the two resonators influences the absorption characteristics, especially in the second and third peaks where the coupling between the inner SRR and outer SRR is strong. The current density distribution indicates that the two resonators oriented in the same direction achieve reduced coupling between them, which results in two absorption frequencies close to each other. For parallel polarization with the electric field parallel to the SRR gap, this study predicts dual-band absorption peaks corresponding to the magnetic resonance at the SRR wire.

Detection of African Trypanosomes Using Asymmetric Double-Split Ring Based THz Sensors

Human African Trypanosomiasis is a highly dangerous tropical disease for which no fast, reliable, and sensitive screening tests are available to date. In this paper, the foundation of a novel electromagnetic sensor concept for aptamer-based direct detection of African trypanosome parasite layers is examined. Special attention is given to the sensitivity of asymmetric double-split ring resonators regarding different resonance modes in dependence on ring gap and target film dimensions. A specific sensor array design is then prototyped and tested using photoresist and actual trypanosome parasite coatings. Its response to different types and mixtures of cells in buffer solution is examined in detail to determine detectability of the parasite in varying dielectric contrast.