Periodic Split-ring Resonator Research Articles

An electrical model to design a Metamaterial Left Hand Antenna

This paper proposes a novel approach to study the Left hand antenna using an adequate electrical model. The structure is composed by a periodic Split Ring Resonator and a metallic wires, that’s why the proposed model take into consideration the model of each element and the coupling between the element. Due to the complexity of the structure, the model becomes very important because it’s simple, accurate and a very fast. Besides, once the model is built, it will be easy to control the structure with any change in the structure, the excitation, the substrate. The proposed antenna was manufactured on a FR-4 epoxy. The antenna is designed to RFID application, exactly for an RFID Reader. The antenna presents a significant gain superior to 16dB, and it is designed to simulate at 2.45 GHz.

Low Scattering Element-Based Aperture-Shared Array for Multiband Base Stations

This article presents a dual-wideband dual-polarized aperture-shared antenna array with low blockage effect between cross-band elements, including a low-band (LB) element with a <inline-formula> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> high-band (HB) antenna array underneath. The radiator of the proposed LB element consists of four slim loops with loaded periodic split-ring resonators (SRRs) for achieving low scattering property in the high band. As a result, the blockage effect of the LB element on the HB antenna array is nearly indistinct. The radiation performance, as well as the S-parameters of the HB elements in the dual-band array, is almost the same as the isolated case. For demonstration, the dual-band aperture-shared antenna array, operating in the LB of 0.69&#x2013;0.96 GHz (32.7&#x0025;) and the HB of 3.3&#x2013;4.2 GHz (24&#x0025;), is fabricated and measured. Besides, the isolated LB antenna and HB array are designed for comparison. Compared with the isolated case, the measured peak gain variation of a <inline-formula> <tex-math notation="LaTeX">$1 \times 4$ </tex-math></inline-formula> HB array in one column is lower than 0.7 dB after adding the proposed LB element. In addition, the radiation pattern variation within 3 dB beam coverage is less than 1.5 dB. Therefore, the proposed dual-band aperture-shared array is very suitable for tackling the integration of 5G and 4G/3G/2G base station antennas.

Multi frequency multi bit amplitude modulation of spoof surface plasmon polaritons by schottky diode bridged interdigital SRRs

Multi-frequency multi-bit programmable amplitude modulation (AM) of spoof surface plasmon polaritons (SPPs) is realized at millimeter wave frequencies with interdigital split-ring resonators (SRRs) and In-Ga-Zn-O (IGZO) Schottky diodes. Periodic SRRs on a metal line guide both SRR mode and spoof SPP mode, the former of which rejects the spoof SPP propagation at the SRR resonant frequencies. To actively modulate the amplitude of spoof SPPs, IGZO Schottky diodes are fabricated in the SRR gaps, which continuously re-configure SRRs to metallic loops by applying bias. Interdigital gaps are designed in SRRs to increase the capacitance, thus red shifting the resonant frequencies, which significantly broadens the operation bandwidth of multi-frequency AM. Thus, cascading different kinds of interdigital SRRs with Schottky diodes enables multi-frequency multi-bit AM programmable. As a demonstration, a dual-frequency device was fabricated and characterized, which achieved significant multi-bit AM from −12.5 to −6.2 dB at 34.7 GHz and from −26 to −8.5 dB at 50 GHz independently and showed programmable capability.

Numerical Calculation of Dispersion Diagrams and Field Distributions of Waves in 3-D Periodic Split-Ring Resonator Media

We present here a fully computational method for obtaining the dispersion diagrams and the field distributions of electromagnetic waves existing in periodic metamaterial structures. Using a finite-element E-B eigenmode formulation, we solve both for the complex propagation constants (eigenvalues) and the field distributions (eigenvectors) of the periodic structure at each given frequency of interest. As a result, we obtain information about the characteristics of the waves inside passbands and stopbands as well. By these means, the mechanisms of interaction of the electromagnetic waves with the eigenmodes of the metamaterials are revealed.

The simulation on absorption properties of metamaterial/GaAs/electrode layer hybrid structure based Terahertz photoconductive detector

Terahertz (THz) photodetectors have attracted great attention from scientists worldwide for their application in security checking, biomedical treatment and astronomical observation of remote stars and distant galaxies. As a typical THz detector, extrinsic GaAs based photoconductive detector is facing critical technical bottlenecks in the epitaxial growth of sufficiently thick and high-quality GaAs absorption layer. In this work, a novel THz photoconductive detector based on metamaterial/GaAs/electrode layer hybrid structure was designed and simulated. By setting the periodic split ring resonator (SRR) structure as 88 μm pitch with 8 μm width, the absorption peaks exist at the wavelength of about 142 and 367 μm, which originate from the resonant cavity and the SRR dipole resonance effect, and the novel device shows a significant enhancement compared with the conventional GaAs photoconductive detector. Thus, the necessary thickness of GaAs absorption-layer is largely reduced, and the resonant absorption peak can be modulated by changing the thickness of absorption layer. This work provides a novel device structure which can solve the critical epitaxial growth bottleneck of GaAs photoconductive detector and used for the astronomical observation, security check, etc.

Miniaturised circularly‐polarised antenna with high‐constitutive parameter substrate

A two-dimensional (2D) high-constitutive parameter (TDHCP) substrate is designed using an artificial metamaterial with high-constitutive parameters. The planar TDHCP substrate is used for miniaturising of a circularly-polarised microstrip patch antenna. A 2D metamaterial unit cell is needed due to the fact that the electric and magnetic vectors are rotating in a circularly-polarised antenna. The proposed TDHCP substrate increases the constitutive parameters of the host substrate. It is composed of periodic split-ring resonators loop circuits embedded in a low dielectric host medium. The TDHCP substrate provides equal permittivity and permeability ( e r ≅ μ r ) at any frequency of interest, which compensates for the bandwidth reduction due to the increased permittivity. The size of the proposed TDHCP substrate antenna at 850 MHz is reduced up to about 72% compared to the conventional microstrip patch antenna. The bandwidth of the antenna is increased compared to high-electric permittivity substrates because of the increased the magnetic permeability. The proposed antenna is fabricated and measured. The simulated and measured results show a good agreement.

Switchable and tunable metamaterial absorber in THz frequencies

Abstract We demonstrated a metamaterial absorber (MMA), which can be controlled by variation of conductivity or temperature. The metamaterial (MM) structure is based on three individual layers of periodic split ring resonator (SRR), a dielectric, and metallic film. The resonant frequency of the designed structure is numerically investigated at THz range of electromagnetic (EM) wave, which is explained by surface current and equivalent LC-circuit. It was found that by replacing the metallic film with VO2, the absorption intensity can be controlled by modification of the conductivity through the optical pumping power, while the absorption frequency is tuned by changing the temperature of InSb material filled into two slits of SRR. It is expected that this work will allow switchable and tunable absorption behaviours for applications of MMA.

Improved Hybrid FDTD Method for Studying Tunable Graphene Frequency-Selective Surfaces (GFSS) for THz-Wave Applications

One hybrid finite-difference time-domain (FDTD) method is proposed for studying transmission characteristics of a THz wave through some tunable dispersive graphene frequency-selective surfaces (GFSSs) biased by an electrostatic or a magnetostatic field, respectively. It integrates auxiliary differential equation (ADE)-FDTD with high-order conformal FDTD (2, 4) so as to handle atomically thin periodic structures on an electrically anisotropic substrate with high flexibility and accuracy. The dispersion error and computational efficiency of the developed algorithm is validated in comparison with the piecewise linear recursive convolution (PLRC)-FDTD and commercial software HFSS, respectively. Numerical studies are further performed to demonstrate its capability for characterizing the effects of chemical potential of graphene, biasing electrostatic and magnetostatic fields, and geometrical parameters of different GFSSs on the central frequencies and 3-dB bandwidths of their passbands and stopbands. In particular, both frequency selectivity and tunability of GFSSs made of single- and double-layer periodic split-ring resonators are predicted, which can be exploited for developing some novel tunable THz structures.

Fano resonances in THz metamaterials composed of continuous metallic wires and split ring resonators.

We demonstrate theoretically and experimentally that Fano resonances can be obtained in terahertz metamaterials that are composed of periodic continuous metallic wires dressed with periodic split ring resonators. An asymmetric Fano lineshape has been found in a narrow frequency range of the transmission curve. By using a transmission line combined with lumped element model, we are able to not only fit the transmission spectra of Fano resonance which is attributed to the coupling and interference between the transmission continuum of continuous metallic wires and the bright resonant mode of split ring resonators, but also reveal the capacitance change of the split ring resonators induced frequency shift of the Fano resonance. Therefore, the proposed theoretical model shows more capabilities than conventional coupled oscillator model in the design of Fano structures. The effective parameters of group refractive index of the Fano structure are retrieved, and a large group index more than 800 is obtained at the Fano resonance, which could be used for slow light devices.

Transmission-Line Model and Propagation in a Negative-Index, Parallel-Plate Metamaterial to Boost Electron-Beam Interaction

A negative-index metawaveguide (NIMW) comprised of stacks of planar metal sheets loaded with periodic split-ring resonator apertures is modeled using a transmission-line (TL) analysis, and analyzed in detail. The proposed model provides a useful tool to extract the wave impedance and effective homogenized parameters of the metamaterial, ideal for design and optimization purposes. The dominant mode of the NIMW is transverse-magnetic, with a large longitudinal component of the electric field that enables its strong interaction with an electron beam and opens new opportunities for microwave generation and radiation detection. The inherent bi-anisotropy of its loaded inclusions is also examined within our TL theoretical framework, and a solution design to suppress its effect is presented. Finally, since the proposed geometry is shown to support an additional transverse-electromagnetic mode due to strong spatial dispersion, proper excitation of the NIMW is discussed and simulated.

An Electrical Model to Design a Metamaterial Left Hand Antenna

This paper proposes a novel approach to study the L eft hand antenna using an adequate electrical model. Th e structure is composed by a periodic Split Ring Resonator and a metallic wires, that's why the proposed model take into considerati on the model of each element and the coupling between the element. Due to the complexity of the structure, the model becomes very important because it's simple, accurate and a very fast. Besid es, once the model is built, it will be easy to control the stru cture with any change in the structure, the excitation, the substr ate. The proposed antenna was manufactured on a FR-4 epoxy. The antenna is designed to RFID application, exactly for an RFID Read er. The antenna presents a significant gain superior to 16d B, and it is designed to simulate at 2.45 GHz.

Magnetic response of split ring resonator metamaterials: From effective medium dispersion to photonic band gaps

On systematically investigating the electromagnetic response of periodic split-ring resonator (SRR) metamaterials as a function of the size-to-wavelength (a/λ) ratio, we find that the stop bands due to the geometric resonances of the SRR weaken with increasing (a/λ) ratio, and are eventually replaced by stop bands due to Bragg scattering. Our study traces the behaviour of SRR-based metamaterials as the resonance frequency increases and the wavelength of the radiation finally becomes comparable to the size of the unit cell of the metamaterial. In the intermediate stages, the dispersion of the SRR metamaterial can still be described as due to a localized magnetic resonances while Bragg scattering finally becomes the dominant phenomenon as a/λ∼1/2.

Permeability Measurement of Split-Ringresonator Metamaterials from Free-Space Transmission-Only Calibration-Independent Methods

A promising calibration-independent microwave method is proposed for complex permeability extraction of metamaterial structures composed of periodic split-ring resonators. For the retrieval process, uncalibrated (raw) complex scattering parameter measurements of three measurement configurations in free-space are utilized. The advantage of the proposed method is that it employs the transmission-only scattering parameters of metamaterial slabs in the permeability retrieval. This approach improves measurement stability and accuracy and eliminates measurement errors, if any, occurring in reflection S-parameters of the slab. It is validated by retrieving the magnetic properties of various homogeneous metamaterial slabs.

The Influence of D-SRRs’ Geometry Dimension on the Resonant Frequency in the LHMs

The study on left-handed materials (LHMs) is a international research hot spot in recent 10 years, the LHMs have important application value in many fields, the study of resonance frequency is the focus of LHMs. Periodic split ring resonators (SRRs) structure is one important method of realization LHMs. The further research of the periodic SRRs structure LHMs is very necessary, the practical value and theoretical value. D-SRRs basic structure new LHMs is put forward, the negative refraction effect of the prism experiment is simulated by D-SRRs basic structure new LHMs. By changing the D-SRRs’ geometry size, the influence of the D-SRRs’ geometry size on resonance frequency of the of the new LHMs is discussed. When D-SRRs’ geometry size is smaller, the frequency response shifts from low frequency response to high frequency response, and frequency response is broadened. These results is great significance for realization LHMs near infrared and visible light.

Permeability Measurement of Metamaterials with Split-Ring-Resonators Using Free-Space Calibration-Independent Methods

A calibration-independent microwave method is proposed for complex permeability extraction of metamaterial structures composed of periodic split-ring resonators. For the retrieval process, uncalibrated (raw) complex scattering parameter measurements of three measurement configurations in free-space are utilized. Two metric functions are derived for retrieval of complex permeability of homogeneous metamaterial slabs even when their lengths are unknown. The method is validated by retrieving the magnetic properties of some homogeneous SRR metamaterial slabs with a pre-assigned magnetic resonant frequency.

A Novel Planar Printed Array Antenna with SRR Slots

Metamaterials, which are composite materials constructed usually by periodic and artificial resonant structures, have been widely utilized in many fields including the antenna design. Quite different from popular methods of embedding an antenna inside a metamaterial or placing metamaterial plates in front of an antenna, this work explores using a metamaterial structure, the periodic split-ring resonator (SRR), to design radiation slots in a printed array antenna for high gain. A proposed array with 4×4 slots and working at 5.8 GHz has been automated designed by using the Genetic Algorithm (GA) in conjunction with the parallel computation on a cluster. Both results of numerical simulations and measurements demonstrate, in comparison with an array using conventional rectangular slots, that the proposed array with SRR slots possesses almost the same impedance bandwidth, side-lobe and cross polarization level, but the gain is improved from 18.7 dBi to 19.6 dBi.

Properties and Numerical Simulation of Electromagnetic Meta-Materials (SRR) Based on Ceramic Substrate

Electromagnetic meta-materials are artificial and periodical materials which both the permittivity and permeability are simultaneously negative. Electromagnetic meta-materials represent a new concept where composite materials are designed to display particular properties. The work which we had finished includes theoretical design and numerical simulation of the structure, fabrication of the samples and measurement of the properties. We designed electromagnetic meta-materials which composed by periodic split ring resonators (SRR) based on ceramics and then researched the influence by microwave guide. It is showed that the resonance frequency of meta-materials can be adjusted by dielectric constant and thickness of ceramic substrate.

Dual-Polarized Frequency-Tunable Composite Left-Handed Slab

A dual-polarized frequency-tunable composite left-handed slab (CLS) is proposed. The CLS consists of periodic split-ring resonators (SRRs) along with thin wires. Two orthogonal SRR/wire arrays are utilized for dual-polarization purposes. Polarization-selectivity and frequency-tuning are achieved by means of on/off switches placed between the rings of the SRR. By opening all of the switches for one array and closing them for the other, the left-handed behavior can be switched on and off, respectively. Frequency-tuning performance is then achieved by turning on/off the switches in the former array. Transmission characteristics of the composite structure are predicted using a fast periodic array simulator based on the hybrid finite element-boundary integral (FE-BI) method in conjunction with the fast spectral domain algorithm (FSDA). Numerical results demonstrate dual-polarization and frequency-tuning performance of the proposed switching configuration.