Resonant Elements Research Articles

Design and implementation of a temperature-insensitive heterogeneous resonant magnetic field sensor

A heterogeneous resonant magnetic field sensor is developed by using a FeGa plate, a quartz crystal double-ended tuning fork (DETF) resonator and a sapphire crystal plate. The double ends of the DETF are bonded to the ends of the magnetostrictive FeGa thin plate through two spacers, forming a resonant magnetic sensitive element. The C-cut sapphire crystal plate as a temperature compensation layer is bonded to the bottom of the magnetic sensitive element. When the temperature fluctuates, the bending deformation caused by the heterogeneous sensitive structure eliminates the thermal stress caused by the thermal expansion effect, thereby reducing the temperature drift of the sensor. The impact of different thicknesses of the sapphire substrate on reducing temperature drift in the sensor is analysed through theoretical calculation and finite element simulation. A sensor prototype was fabricated with a sapphire substrate thickness of 0.45 mm. The experimental results demonstrate that the temperature coefficient of frequency (TCF) of the sensor is reduced from 8.73 Hz/°C to 0.47 Hz/°C in the 0 °C to 60 °C range, and the sensitivity and resolution in the linear region of the sensor are 5.63 Hz/Oe and 42μOe (4.2nT), respectively.

All‐Dielectric High‐Q Dynamically Tunable Transmissive Metasurfaces

AbstractActive metasurfaces, which are arrays of actively tunable resonant elements, can dynamically control the wavefront of the scattered light at a subwavelength scale. To date, most active metasurfaces that enable dynamic wavefront shaping operate in reflection. On the other hand, active metasurfaces operating in transmission are of considerable interest as they can readily be integrated with chip‐scale light sources, yielding ultra‐compact wavefront shaping devices. Here, designs for all‐dielectric low‐loss active metasurfaces which can dynamically manipulate the transmitted light wavefront in the near‐infrared wavelength range are reported. The active metasurfaces feature an array of amorphous silicon (a‐Si) pillars on a silica (SiO2) substate, which support resonances with quality factors (Q‐factors) as high as 9800. The high‐Q resonance dips observed in transmission can be transformed into transmission resonance peaks by positioning a‐Si pillar resonators at a prescribed distance from a crystalline Si substrate. The design of metasurface geometry with realistic interconnect architectures that enable thermo‐optic dynamic beam switching with switching times as low as 7.3 µs is reported. Beam switching is observed for refractive index differences between neighboring metasurface elements as low as 0.0026. It is shown that the metasurface structures with realistic interconnect architectures can be used for dynamic beam steering.

Validating an algebraic approach to characterizing resonator networks

Resonator networks are ubiquitous in natural and engineered systems, such as solid-state materials, electrical circuits, quantum processors, and even neural tissue. To understand and manipulate these networks it is essential to characterize their building blocks, which include the mechanical analogs of mass, elasticity, damping, and coupling of each resonator element. While these mechanical parameters are typically obtained from response spectra using least-squares fitting, this approach requires a priori knowledge of all parameters and is susceptible to large error due to convergence to local minima. Here we validate an alternative algebraic means to characterize resonator networks with no or minimal a priori knowledge. Our approach recasts the equations of motion of the network into a linear homogeneous algebraic equation and solves the equation with a set of discrete measured network response vectors. For validation, we employ our approach on noisy simulated data from a single resonator and a coupled resonator pair, and we characterize the accuracy of the recovered parameters using high-dimension factorial simulations. Generally, we find that the error is inversely proportional to the signal-to-noise ratio, that measurements at two frequencies are sufficient to recover all parameters, and that sampling near the resonant peaks is optimal. Our simple, powerful tool will enable future efforts to ascertain network properties and control resonator networks in diverse physical domains.

Fractal Cross-Slot-Coupled Antenna with Dielectric Resonator Elements having Circular Polarization

This article presents the design and analysis of an “ultra-wideband (UWB)” Fractal Cross-slot-Coupled Antenna with “Dielectric Resonator Elements (DREs)” exhibiting circular polarization and band-notched characteristics. The proposed antenna aims to reject the frequency range of 5.1 GHz to 5.9 GHz while maintaining high impedance bandwidth and radiation efficiency. A coplanar waveguide feeds the planar UWB antenna, featuring a narrow slot on the radiating element and a dielectric resonator mounted on top. Simulation results demonstrate excellent performance in terms of impedance bandwidth and radiation efficiency. To further improve the design for wireless applications, Fractal-slot-aperture coupled DRE antennas are employed. The proposed configuration takes into account the radiative efficiency and concomitant excitation of the rectangular DRE by a “Circularly Polarized Dielectric Resonator Antenna (CPDRA)” coupled through a fractal cross-slot. By appropriately adjusting the fractal cross-slot size, a wider “axial ratio (AR)” bandwidth is achieved through the combination of its resonance with the dielectric resonator. The antenna is designed utilizing the proposed fractal cross-slot-coupled CPDRA, with its architecture and efficiencies thoroughly investigated. The performance of the proposed antenna demonstrates its potential for various wireless communication applications, highlighting the advantages of integrating Fractal Cross-slot-coupled DREs in antenna design.

1D Photonic Topological Insulators Composed of Split Ring Resonators: A Mini Review

AbstractIn recent years, topological photonics inspired by electric topological insulators has promoted extensive research on robust electromagnetic (EM) wave manipulation and new wave‐functional devices. Optical resonators can significantly confine EM waves and are the basic building blocks for constructing diverse topological structures under a tight binding mechanism. As an artificial “magnetic atom,” the split‐ring‐resonator (SRR) is one of the most attractive optical resonators. SRRs provide an excellent and flexible platform for constructing various topological structures with complex coupling distributions, uncovering abundant topological properties, and innovating practical devices. Here, the realization and fundamental EM responses of the SRR are briefly introduced. Compared to conventional EM resonance elements, the coupling between SRRs depends not only on the coupling distance but also on the orientation angle of the slits. The recent achievements in various low‐dimensional photonic topological structures composed of SRRs are summarized. Furthermore, this review explains the underlying physical principles and discusses progress in topological devices with SRRs, including wireless power transfer, sensing, and switching. Finally, this review provides an overview of the future of SRR topological structures and their impact on the development of novel topological systems and devices.

Hybrid Control-Based Closed-Loop Soft Start-Up Method for LLC Resonant Converters

LLC resonant converters are prone to generating a large inrush current during the start-up process, which will cause damage to the resonant elements and threaten the safe operation of the circuit. In this study, we investigate the soft-start method to suppress the inrush current of an LLC resonant converter. Based on the traditional frequency-decreasing method, we integrate PWM control to broaden the output voltage gain range during the start-up. Additionally, to ensure the smooth establishment of the output voltage, the controller performs the closed-loop control of the duty cycle and frequency in sequence based on the rate of output voltage rise. A prototype experiment based on STM32F334C8T6 is established to experimentally validate the presented soft start-up method. The experiment results indicate that the soft start-up method improves the start-up performance, reduces the maximum inrush current by 47.5% compared with that of the frequency-decreasing method, and builds up the output voltage quickly. The start-up process is smooth, which improves the reliability of the LLC resonant converter.

Dual Band 1x4 Linear Metamaterial Bowtie Antenna Array for Autonomous Vehicle in Public Safety Band Communications

This research presents the design, simulation, and fabrication of a dual-band 1x4 linear metamaterial bowtie antenna array for applications in 5G wireless systems and public safety band communications. The single-element antenna is a compact dual-band structure with a complementary split-ring resonator (TCSRR) element, and it exhibits resonant frequencies of 3.5 GHz and 4.9 GHz, covering the sub-6GHz 5G spectrum and the public safety band. The antenna aray design is optimized for impedance matching and radiation efficiency. The 1x4 linear antenna array is designed with a quarter-wave transformer feed network and carefully controlled mutual coupling to enhance gain and directionality. Simulated and measured results confirm the performance of the array, with a reflection coefficient within -10 dB from 3.2 GHz to 3.85 GHz and from 4.55 GHz to 5.95 GHz and 3.45 GHz to 3.75 GHz and 4.45 GHz to 5.7 GHz, respectively. The array exhibits a peak realized gain of up to 8.7 dBi and efficient radiation patterns. This work offers promising insights into the development of antenna systems for advanced wireless communication applications and vehicle-to-vehicle communication in public safety band.

A Simplified Design Method for Quasi-Resonant Inverter Used in Induction Hob

Induction heating (IH) technology is widely recognized and utilized in residential applications due to its high efficiency and safe operating characteristics. Resonant inverter circuits are widely used in IH systems because of their high efficiency and ability to perform soft switching. Among the various resonant inverters used in IH systems, the single-switch quasi-resonant (SSQR) inverter topology is typically preferred for low-cost and low-output-power applications. Despite its cost advantage, the SSQR topology has a relatively narrow soft-switching range, which can be unstable depending on the electrical parameters of the load and the resonant converter circuit. Accurately determining the capacitance value of the resonant capacitor and the inductance value of the induction coil, which are the key circuit elements of the SSQR induction cooker, is crucial for designing a reliable, efficient, and durable cooking system. In other words, there exists a critical relationship between the resonant converter circuit parameters, load characteristics, and safe operating conditions. Additionally, when considering closed-loop control methods used for power control and safety, selecting appropriate resonant circuit elements becomes vital in ensuring both reliable and efficient operation. This paper focuses on a novel and simplified design method for the SSQR inverter utilized in household appliances. The proposed method and its advantages in terms of the safe operating area of the switch are theoretically investigated and verified through simulations and prototype circuits.

Elastic metamaterials with gradings and their structural applications

Graded designs allowing a progressive wave manipulation have been a cornerstone for the design of functional structures. Either based on local resonance, Bragg scattering or a mix of both, the performance of graded meta go much beyond the so-called bandgap, the original hallmark of elastic metamaterials. I will present different applications where elastic metamaterials featuring graded design have been studied and exploited for different purposes and scales. After introducing early proposals with EM and acoustic waves, applications on graded resonant metasurfaces will be showcased. These include both fundamental laboratory scale experiments but also civil and mechanical engineering-oriented applications for vibration energy harvesting and vibration suppression. I will then show the latest experimental efforts in modeling, optimising and 3D printing lightweight frame-based panels for structural engineering applications. These frames combine lightweight, bioinspired shapes with graded resonant elements and represent a promising design model for reimaging the design of structural members such as trusses, beams and shells integrating vibration control and application in structural engineering and architecture.

The integration of metamaterials into building elements

The building industry continues to rely on homogeneous materials for acoustic insulation despite the progress of research into acoustic metamaterials. With the inevitable densification of housing, the severity of noise pollution within residential living environments is escalating. While the insulation of high-frequency audible sound through building elements is often relatively good between 1 and 5 kHz, the overall acoustic transmission loss performance is often significantly limited by two specific frequency regions. The mass air mass resonance band, and the coincidence band. We present the results of an investigation into the use of metastructures and metasurfaces to improve transmission loss in these frequency regions with a focus on scalable implementation. These metastructures are metamaterial systems constructed from impedance change elements, surface variations and vibroacoustic resonant elements. The performance of selected systems from this research are presented. Experimental and modeling results are in good qualitative agreement and promising diffuse-field testing results indicate significant attenuation within the targeted band regions. The merits of each technique are analysed, and results indicate which methods are most effective at either mitigating or shifting the regions of poor transmission loss outside of the most important part of the audible frequency region.

Шумоизолирующий кожух с резонаторными элементами

Constant exposure to industrial noise has a negative impact on the human body. That is why increased attention is paid to the fight against noise, the rationing of industrial noise and vibrations was adopted. One of the effective methods to reduce the noise emitted by the operating equipment is the use of noise-insulating casings. The casing, as a rule, contains an outer skin made of steel sheet, a sound-absorbing lining of the inner skin, a perforated lining of a sound-absorbing coating. A typical octave spectrum of radiation sound pressure levels near the machine has a maximum near the frequency of 500 Hz, and the highest casing efficiency (insertion loss) is achieved in the frequency range of 1000–4000 Hz. The purpose of the study presented in the article is to improve the acoustic properties of the noise-insulating casing in the medium and low-frequency sound spectrum. To accomplish this task, the author proposes integrating resonator elements, in particular, Helmholtz resonators, into the structure of the noise-insulating casing. The natural resonant frequencies of Helmholtz acoustic resonators are determined considering their necessary frequency tuning, which ensures effective suppression of sound radiation at discrete values of the operating dominant frequencies of operating equipment. To reduce the excitation of structural vibrations and sound, as well as additional sound insulation, the frame walls and casing covers are damped on the outside and inside with a layer of vibration-damping material. Significant absorption of sound waves generated by operating equipment is ensured by lining the casing walls with effective sound-absorbing panels made of porous material, lined, in turn, with an external protective sound-transparent layer. The design of a noise-insulating casing with resonator elements presented in the study has high acoustic properties in a wide frequency range. Helmholtz resonators built into the casing structure provide sound absorption in 1/3 octave frequency bands centered at 400 and 500 Hz, characterized by a resonant amplification of the sound emitted by the equipment discussed in the article.

Symbolic purposes of style: Ruben Östlund’s The Square

Symbolic criticism is easily reduced to an act of translating meaning, remote from the style of rich narratives. Drawing on David Bordwell’s distinction between broad, overlapping functions of style, I argue that we can examine symbolic purposes as secondary to decorative and expressive purposes. I show how a theory on conceptual cognition proposed by psychologist Lawrence Barsalou can let the critic transcend firm distinctions between abstract and concrete features of a narrative. This proves especially helpful when narrative purposes are downplayed, for example in the resonant elements of art cinema, affecting how we construct and experience the storylines. I posit a framework for the analysis of symbolic purposes based on general mechanisms of memory and attentional guidance, letting us see continuity with critics such as Bordwell and Victor F. Perkins. This approach enables the critic to distinguish between degrees of symbolic power in Ruben Östlund’s The Square.

Microstrip dual band hybrid directional resonator antenna with volume reduction

This paper presents a novel design of a single-layer, horizontally polarized, dual-band, omni- and multi-directional hybrid dielectric resonator antenna (DRA) feeding through a 50 Ω coaxial connector. The proposed antenna consists of an FR4 substrate, a regular ground plane and a cross-shaped patch. The connector is placed at the middle point of the square ground plane. Above the microstrip patch, four similar solid dielectric resonator elements are placed diagonally. These DRA structures generate the TE111, hybrid HEM22δ modes and put up an ideal magnetic dipole and an electric quadrupole far-field radiation pattern. To verify the idea, an optimized antenna model is fabricated and tested. A reasonable agreement between the measured and simulated results is obtained. The measured impedance bandwidths of the TE111 and HEM22δ modes are 4.26 % (2.9–3.2 GHz) and 4.34 % (4.4–4.6 GHz), respectively. The proposed antenna has a stable omnidirectional radiation pattern at the first resonance frequency and a directional radiation pattern at the second resonance frequency and provides volume reduction.

A Switching-State Equivalent Gain Method for the Design of Dual-Transformer Wide Gain Range LLC Resonant Converter

Dual transformer resonant tank (DTRT) structure has been increasingly applied in the LLC resonant DC-DC converters to meet the demand for ultra-wide gain range in the utilization of renewable energy. Due to the structural particularity, the analysis of its gain characteristics and the design of topology are still rather complicated. In this paper, the parameter equivalent model of DTRT structure is derived from the traditional LLC converter to optimize the design of resonant elements. On this basis, the port theory based on mathematical model is proposed to quantify the relationship between the gain characteristics and the switching-states of the front-stage inverter. Inductively, the switching-state equivalent gain (SSEG) method was abstracted to broaden the total gain range within limited frequency range by mode splicing, and to guide the design of topology and operation strategy. To verify the theoretical analysis and the performance of proposed method, a 40-320V DC input, 96V DC output, 300W prototype was built up and applied in various inverter configurations. Analysis and experimental results indicate that the SSEG method is applicable to all kinds of DTRT based converters, representing the operating characteristics consistent with of the traditional converter but with an ultra-wide gain range.

Liquid Characterization of 2 GHz Complimentary Split Ring Resonator (CSRR) for Water Quality Applications

This study describes a complementary split-ring resonator (CSRR)-based planar microwave sensor. Its capability in detecting several samples which are based on the usual water contaminant in Malaysia was investigated. The CSRR sensor was designed with an unloaded resonant frequency of 2.0 GHz, and it was fabricated on an FR-4 substrate with a thickness of 1.6 mm and a dielectric constant of 4.3. The S-parameter responses of the sensor were measured under two conditions; i) unloaded and ii) loaded. For the latter, samples of tap water, salt water, isopropyl alcohol, filtered water and cooking oil were used to load the resonant element of the CSRR. The measurement result of unloaded CSRR shows that the designed sensor resonates at 1.99 GHz, which is in line with the simulation. The measurement results also showed that the presence of all samples caused the resonant frequency of the CSRR to shift, with filtered water and cooking oil showing the biggest frequency shifts (0.84 GHz and 0.96 GHz, respectively). A sensitivity analysis of the CSRR was carried out and it shows that it achieves 0.25% sensitivity. The proposed sensor may be a useful substitute for pricey commercial sensors for applications involving water quality because of the inexpensive materials and ease of fabrication.

An Improved Performance Radar Sensor for K-Band Automotive Radars.

This paper presents a new radar sensor configuration of a planar grid antenna array (PGAA) for automotive ultra-wideband (UWB) radar applications. For system realisation, the MIMO concept is adopted. The proposed antenna is designed to operate over the 24 GHz frequency band. It is based on split-ring resonator (SRR) elements to enhance the operating bandwidth and increase the antenna gain, leading to a better-performing radar system. The PGAA consists of thirty-one radiating elements, in which each element excitation is obtained using a common transmission line centre fed by a 50 Ω coaxial probe. By introducing a superstrate dielectric layer at a distance of λ/2 from the top of the antenna array, the PGAA gain and impedance bandwidth are further improved. The gain is improved by 2.7 dB to reach 16.5 dBi at 24 GHz, and the impedance bandwidth is enhanced to 9.3 GHz (37.7%). The measured impedance bandwidth of the proposed antenna array ranges from 20 GHz to 29.3 GHz for a reflection coefficient (S11) of less than -10 dB. The proposed antenna is validated for automotive applications.

Slot driven dielectric electromagnetically induced transparency metasurface.

The control of resonant metasurface for electromagnetically induced transparency (EIT) offers unprecedented opportunities to tailor lightwave coupling at the nanoscale leading to many important applications including slow light devices, optical filters, chemical and biosensors. However, the realization of EIT relies on the high degree of structural asymmetry by positional displacement of optically resonant structures, which usually lead to low quality factor (Q-factor) responses due to the light leakage from structural discontinuity from asymmetric displacements. In this work, we demonstrate a new pathway to create high quality EIT metasurface without any displacement of constituent resonator elements. The mechanism is based on the detuning of the resonator modes which generate dark-bright mode interference by simply introducing a slot in metasurface unit cells (meta-atoms). More importantly, the slot diameter and position on the meta-atom can be modulated to tune the transmittance and quality factor (Q-factor) of the metasurface, leading to a Q-factor of 1190 and near unity transmission at the same time. Our work provides a new degree of freedom in designing optically resonant elements for metamaterials and metasurfaces with tailored wave propagation and properties.

Research on Power Decoupling and Parameter Mismatch of Three-Port Isolated Resonant DC–DC Converter Applied Switch-Controlled Capacitor

In order to realize the controllable power decoupling and eliminate the influence of the parameter error of the resonant elements, a three-port DC-DC converter applied switch-controlled capacitor is proposed. The operating principle and transmission power expression of the proposed three-port converter under triple-phase-shift control are analyzed. By adjusting the phase shift angle of the switch-controlled capacitor (SCC) to adjust the resonant frequency of the resonant tanks, the topology-level power decoupling of the circuit at a constant frequency can be achieved. The addition of switch-controlled capacitors provides more freedom for power regulation between ports. Besides, according to the proposed converter, a design method for the parameters of the resonant tank is proposed to eliminate the adverse effects caused by the parameter error of the resonant elements. Then an optimized triple-phase-shift modulation strategy is adopted to achieve the minimum RMS value of the resonant converter. An experimental prototype was designed to verify the correctness of the proposed converter and modulation strategy.

An equivalent lattice-modified model of interfering Bragg bandgaps and Locally Resonant Stop Bands for phononic crystal made from Locally Resonant elements

The design and development of advanced devices based on metamaterials to control the transmission of acoustic waves is a hot topic. An important class of these metamaterials is based on phononic crystals with Locally Resonant Structure, included in those commonly known as Locally Resonant Sonic Materials. In these metamaterials, wave control is basically performed by two mechanisms: internal (or local) resonances in the scatterers that form the phononic crystal, and Bragg bandgaps due to structural periodicity. Their main control feature is the resonance peaks forming additional stop-bands away from the Bragg frequency, mainly in the low frequency regime. For some applications, coupling of the two phenomena is necessary to create a broad transmission gap. However, when both are located in close frequency ranges, some destructive interferences can occur. In this paper, the authors develop a comprehensive numerical model of periodic arrays of Hemholtz resonators, which explains in detail the physical mechanisms of this destructive interference and, simultaneously, allows the reproduction of the consequences of the interference. The numerical results are supported by experimental tests.

Development of ultra-broadband sound absorber based on double-layered irregular honeycomb microperforated panel

In this study, a broadband sound absorber was developed using a double-layered irregular honeycomb microperforated panel (MPP) structure and a particle swarm optimization (PSO) algorithm to address the issue of broadband sound absorption of MPPs. An acoustic impedance model of the designed sound absorber and an optimization algorithm were implemented to obtain the structural configuration parameters for quasi-perfect sound absorption. The coupling effect between the resonant elements and the optimized structural configuration parameters enabled broadband and high-efficiency sound absorption. The impedance tube experimental results demonstrated an excellent broadband sound absorption level within the range of linear acoustics, and the designed triad and tetrad structures exhibited more than 70% absorption efficiency in the range of 609–4 002 Hz and 518–5 162 Hz, respectively. This study provides a design method and insights into the design, promotion, and application of broadband sound absorbers.