Comparison of single and concentric split-ring resonator generated microplasmas

Inspired by the dendritic geometry in nature, we designed the single dissymmetrical hexagonal split ring resonators (SRRs). The SRRs were fabricated on one side of the dielectric substrate using shadow mask/etching technique. By experiments and computer simulations, we have researched the microwave transmission behavior of the SRRs in the frequency band of 7—12 GHz. The results show that, for an individual hexagonal SRR, the resonance frequency is affected by the size of the SRR; for two SRRs, there are two resonance peaks in the transmittion curve when they are close to each other. For three SRRs or the radialized rings, the resonance frequency of the structure with high-level branches shifts towards lower values compared with that with no branches. The simulations are in agreement with the experimental results.

This paper had been comparing the performance of the normal patch antenna with single complimentary SRR patch antenna. Four different shapes of single complimentary split ring resonator structure had been incorporated into the microstrip patch antenna - square, circular, triangular, and rhombic. This simulation works had been done in CST Microwave Studio simulation software. The operating frequency of this antenna is 2.40 GHz for Wireless Local Area Network (WLAN) application. The parameters that considered in these works are return loss, resonant frequency, input impedance, gain, radiation pattern and bandwidth. The focusing parameter is to achieve the best gain performance that obtained from the single complimentary split ring resonator patch antenna. The addition of square SRR onto patch antenna will improve the gain from 6.334 dB to 6.508 dB.

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

An ultra-wideband three-layer 90° polarization rotator based on double split-ring resonators is proposed in this paper. The structure is constructed from three layers separated by two air gaps. The top and bottom layers are wire grid orthogonal to each other, while the middle layer consists of double split-ring resonators. The purposed polarization rotator is able to rotate the incident linearly polarized plane wave in the frequency band from 3.70 to 14.76 GHz with a minimum of 90% cross-polarization transmission. Compared to previous works based on single split-ring resonator, our improved design exhibits a fractional bandwidth of 119.8%, which is wider than the reported design by 27.2%.

Split-ring resonators (SRRs) are one of the most common building blocks to design metamaterials operating over a large range of frequencies in the electromagnetic spectrum. Here we acquire s-SNOM images with high signal-to-noise ratio on SRRs by scattering-type scanning near-field optical microscopy (s-SNOM) in the terahertz (THz) domain. By mapping the electric field distribution with subwavelength spatial resolution, we observe clear spatial asymmetries within a single SRR. These effects are more pronounced for the SRRs designed to resonate at the frequency of the probing laser (2.52 THz), compared to the SRRs that do not support a resonant mode at this frequency. This asymmetrical distribution is attributed to combined far-field and near-field multiplication effects, which depend on the position of the probing tip on the micro-resonator.

Negative magnetic permeability of single split-ring resonators (SSRRs) is theoretically investigated in the visible light region. To describe the conduction characteristics of metal in the visible range, we develop the internal impedance formula completely. In our calculations, we determine the magnetic responses of the SSRR accurately. Based on our investigations, we also demonstrate the negative mu of the silver SSRR array in the visible light region.

An asymmetric planar terahertz (THz) metamaterial (MM) is designed to be composed of two different single split-ring resonators (SRR) and its character is simulated in the THz region. Gallium arsenide (GaAs) is inserted between the gap of two separated single SRR, and through modulation of its conductivity (σ GaAs ) we achieved the switching of three different resonance modes and researched the influence of σ GaAs on transmission of MM. The resonant structure of MM can be switched from the two fundamental LC-modes to the new LC-mode and dipole resonance mode through the coupling LC-mode with the increasing σ GaAs . Such dynamical control of MM resonances provides an efficient way to manipulate electromagnetic wave to push mode-switching of resonance and could be implemented in terahertz devices to achieve additional functionalities.

Electromagnetic metamaterials (MMs) consisting of highly conducting sub-wavelength metallic resonators enable many unusual electromagnetic properties at user defined frequencies which are not permissible with the naturally occurring materials [1, 2]. Generally the electromagnetic properties of metamaterials are controlled by the design variation of the MM unit cell, often termed as meta-molecule, consisting of single or multiple metallic split ring resonators (SRRs). These metallic resonators are quite often termed as meta-atoms too. The near field electromagnetic coupling between these meta-atoms exhibits an important role in modulating the fundamental resonances of the metamaterials [3-5].

In this article, a metasurface (MS) is placed as superstrate to counteract the effect of mutual coupling in linear antenna array in X-band. The metasurface is single layered and consist of single split ring resonator (SRR) and two I-shaped structures. The proposed metasurface can curb the interactions between adjacent antenna elements by collimating the electric field and reduce horizontal magnetic field interactions due to its negative refractive index and mu-near-zero property. The functioning of metasurface is tested by placing it above a 1×3 patch antenna. The experimental measurement shows an isolation below -25 dB in the 5.12% operational bandwidth with maximum isolation of -38.2 dB for an edge-to-edge distance of only 0.16λo. The active radiation pattern indicates an improved cross-polarization levels to below -30 dB, in both the orthogonal planes. The performance of MS is further tested for a 1×7 linear array where a 9.2 dB reduction in coupling value is observed. On placing the MS on the array there is no change in the operational bandwidth indicating that no modifications is needed in the antenna array geometry making it a preferable and easily transferrable solution to already existing antenna array.

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).

We have numerically investigated the photon-magnon coupling in the system of coupled anapole resonators (metasurface). A strong spin-number-normalized coupling strength (single spin-photon coupling) g e f f /2πN was reached up to 0.276 Hz (g eff /2π = 310 MHz) at a frequency of 9.7 GHz compared to the spin-number-normalized coupling strength in a single splitring resonator (SRR) g e f f /2πN=0.097 Hz(g e f f /2π=270MHz).

In this paper, a 105GHz millimeter wave interferometer system is used to measure the electron density and temperature of an atmospheric pressure helium plasma driven by submicrosecond pulses. The peak electron density and electron-neutral collision frequency reach 8×1012cm−3 and 2.1×1012s−1, respectively. According to the electron-helium collision cross section and the measured electron-neutral collision frequency, the electron temperature of the plasma is estimated to reach a peak value of about 8.7eV.

A novel composite right-/left-handed transmission line (CRLH TL) and its equivalent circuit model are proposed based on cascaded complementary single split ring resonator (CCSSRR). It features an intrinsically balanced wider band and an additional transmission zero above the right-handed band relative to CRLH TL using complementary single split ring resonator and complementary split ring resonators. Moreover, two single negative (SN) metamaterial (MTM) TLs constructed by using complementary electric inductive-capacitive resonator on the conductor strip and on the ground, respectively, are researched. Both SN MTM TLs exhibit electric resonance above the fundamental magnetic resonance. For application, a monoband (MB) bandpass filter (BPF) covered WLAN band, and a dual-band (DB) BPF covered satellite DMB band and WiMAX band are designed, fabricated, and measured. The SN MTM TLs are adopted for the sake of deep and wide out-of-band suppression while CRLH MTM TLs using square-shaped and Sierpinski-shaped CCSSRR are critical factors of the MB and DB behavior. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

We present the design, fabrication, and characterization of a band pass filter with a center frequency of 28 GHz using a Half Mode Substrate Integrated Waveguide (HMSIW) architecture on a smooth and thin fused silica substrate for the reduction of insertion loss. Filter properties are implemented by using a single complimentary split ring resonator (CSRR) structure. High out-of-band attenuation is achieved by using four spur line structures embedded in the microstrip feed line, which contributes to overall size reduction of the device. Design is simulated using high frequency structural simulator (HFSS). Devices are fabricated using laser machining and microfabrication. The measured insertion loss is 3dB and the total area of the device is 5.719 mm^2.

High-order harmonic generation (HHG) in solids—the frequency up-conversion of an optical signal—is governed by symmetries. At terahertz (THz) frequencies, HHG is a key technology to access high-frequency spectral windows that are usually difficult to cover using conventional solid-state laser technologies. This effect has been recently exploited in graphene, where HHG has been demonstrated, albeit only at odd multiples of the driving frequency owing to its inherent centro-symmetry. In topological insulators (TIs), the combination of spin–orbit interaction and time-reversal symmetry create an insulating bulk state with an inverted band order, inseparably connected with conducting surface states. TIs have been predicted to support unconventional high harmonic generation from the bulk and topological surface, which are usually difficult to distinguish. However, no experimental results have been reported, so far. Here, we exploit the strong optical field amplification provided by an array of single or double split ring resonators, with embedded Bi2Se3 or (InxBi(1−x))2Se3/Bi2Se3 Van der Waals heterostructures, to achieve up-conversion in the 6.4 (even)–9.7 (odd) THz frequency range. This results from bulk centro-symmetry (odd states) and symmetry breaking in the topological surface states (odd and even).