Adjacent Resonators Research Articles

Metamaterial sensor based on rectangular enclosed adjacent triple circle split ring resonator with good quality factor for microwave sensing application

In this article, a novel shaped metamaterial sensor is presented for the recognition of various oils, fluids, and chemicals using microwave frequency. The performance of the designed sensor structure has been studied both theoretically and experimentally, and it works well. A new sample holder for convenient operation is created and located just behind the designed structure. The results of this study performed better than those of prior liquids sensing studies. Various designs were explored using the Genetic Algorithm (GA), and it is embedded in the Computer Simulation Technology (CST) microwave studio, to optimize the optimal dimensions of the resonator. The suggested metamaterial sensor has a good-quality factor and sensitivity in both frequency shifting and amplitude changing. The resonance frequency shifted to 100 MHz between olive and corn oils, 70 MHz between sunflower and palm oils, 80 MHz between clean and waste brake fluids, and 90 MHz between benzene and carbon-tetrachloride chemicals. The quality factor of the sensor is 135, sensitivity is 0.56, and the figure of merit is 76 which expresses its efficient performance. Furthermore, the proposed sensor can sensitively distinguish different liquids by using the frequency shifting property. The study was carried out in three stages: dielectric constant (DK) measurement with the N1500A dielectric measurement kit, simulation of the structure, and experimental test study with the vector network analyzer. Since the recommended sensor has high sensitivity, good quality factor, and excellent performance, hence it can be used in chemical, oil, and microfluidic industries for detecting various liquid samples.

New synergy effects of the lower hybrid wave and the high harmonic fast wave current drive

The combined drive current of the lower hybrid wave (LHW) and the high harmonic fast wave (HHFW) was studied theoretically for the first time, based on the use of low and higher β e operational parameters in EAST. Broad and significant synergistic effects are found in the simulation, the current drive (CD) efficiency is greatly improved, and the current profile is modified as a result of the synergy between the two types of waves. The LHW interacted with the resonant electrons in low parallel velocity region and pushes them into the adjacent resonance region of the high phase velocity wave (HHFW), thus the number of fast electrons resonant with the HHFW is increased dramatically, and the driven current is enhanced. Therefore the synergy effect strongly depends on the positional relation between the velocity resonance regions of the two waves. Moreover, the effects of the parallel refractive index, the wave frequency and the wave power on the synergy effect are examined. Some problems well known in the single LHW CD or the HHFW CD may be overcome by the combined CD.

Connections between unit cells in locally resonant metamaterials and their impact on the effectiveness of noise mitigation by its base structure

Locally resonant metamaterials (LRS) for sound and vibration mitigation have been a widely investigated topic in the field of acoustic in recent years. Many articles and projects describe fundamental problems of LRS design, numerical simulation, and laboratory measurements. However, there is a noticeable knowledge gap between laboratory prototypes and the mass production (development for a wide-scale implementation) of metamaterials structures. In general, the LRS prototypes require specific boundary conditions, for example, equal spacing between the individual resonators and separate attachment of each resonator to its base. These conditions allow for many simplifications in calculations. At the same time, these boundary conditions create a problem when it comes to the mass production of the LRS structures. Creating a connection between adjacent resonators would allow easier postprocessing of structures ex. attaching the structure to the base and keeping specified distances between resonators. This project investigates the possibilities of creating connections between adjacent unit cells and their influence on the simulation and measurement results. The effect on the simulated band gaps and sound transmission loss is investigated at the stage of numerical simulations. The prototypes of structures are 3D printed and tested. The laboratory measurement results are compared with simulations and further discussed.

Novel tunable dual‐band filter using evanescent‐mode cavity resonators

AbstractIn this paper, a dual‐band filter with highly selective channels and independently tunable channels using evanescent‐mode cavity (EVA) is proposed. It consists of four EVA resonators, each of which is topped by a piezoelectric actuator, which is tuned with frequency. Four sets of varactors between two adjacent resonators are used to tune interstage coupling while four sets of varactors are used between ports and resonators for control of the external coupling. By governing resonant frequencies of the EVA resonators and coupling coefficients between adjacent resonators, the independent center frequency tuning ranges of the lower passband and higher passband of the dual‐filter are 2.05–2.55 and 2.35–2.75 GHz, respectively. Simulation and measurement results maintain the good agreement.

Compact Microstrip Wideband Cross-Coupled Inline Bandpass Filters With Miniaturized Stepped-Impedance Resonators (SIRs)

This paper presents a class of reduced footprint inline microstrip bandpass filters capable of covering bandwidth up to 20% as well as good flexibility in establishing various cross-couplings for creating transmission zeros. The resonating elements are quarter-wave stepped-impedance resonators (SIRs), which have a wide upper stopband in nature. To achieve size miniaturization, the low-impedance segment of each SIR is implemented as a thick-trace ring and configured in a spiral form, and the high-impedance section is deformed to accommodate the low-impedance section. An interlaced coupling structure is proposed to enhance the coupling limited by the downsized coupled segments of adjacent resonators. In addition, by properly routing the associated shorted stubs, the structure can easily establish cross-coupling between nonadjacent resonators. Thus, compact SIR filters in an inline arrangement can be achieved to have either narrow or wide passbands with multiple transmission zeros. Two such circuits with sharp transition bands and upper stopband extension are synthesized, fabricated, and tested. The measured results show good agreement with simulated data. The circuit areas together with the performances of the experimental filters are compared with those in existing literature.

Identification of the excitation source's circumferential position for rotating blades based on vibration phase

Wake excitation is the main cause of synchronous vibration of large rotating machines’ blades, whose circumferential position reflects the distortion position of flow field. However, little research has been published concerning the identification of excitation source's circumferential position based on blade vibration parameters. A new identification method using vibration phase is proposed in this paper. The excitation force model is established along with the forced vibration response model of blades under excitation sources. A phase unwrapping method is proposed to solve phase ambiguity, and the excitation source's circumferential position is achieved through vibration phase and engine orders of the same rotating blade in adjacent resonance regions. Experimental results verified the effectiveness and accuracy of the proposed method. The identification error of excitation source's circumferential position is less than ±1°.

A Novel Microstrip Triple Wideband Bandstop Filter Design by Using Adjacent Direct Coupled Dual-Mode Resonators

In this article, a novel triple wideband bandstop filter design is proposed with two adjacent microstrip square loop resonators (MSLR) having different edge lengths. Degenerate modes of the square loop resonators are induced by using direct coupling mechanism. Perturbation and loading elements are located on resonators and used to control reflection zeros between the second and third bands. Even odd mode analysis of a single direct coupled dual-mode resonator is also extracted to elucidate the filter topology. The proposed resonator structure is designed by using a full-wave EM simulator and three different filter responses are obtained from the designed resonator structure. One of the filters is fabricated and, it is observed that measured results are compatible with simulated results.

Continuous radio-frequency electric-field detection through adjacent Rydberg resonance tuning

We demonstrate the use of multiple atomic-level Rydberg-atom schemes for continuous frequency detection of radio-frequency (RF) fields. Resonant detection of RF fields by electromagnetically induced transparency and Autler-Townes (AT) splitting in Rydberg atoms is typically limited to frequencies within the narrow bandwidth of a Rydberg transition. By applying a second field resonant with an adjacent Rydberg transition, far-detuned fields can be detected through a two-photon resonance AT splitting. This two-photon AT splitting method is several orders of magnitude more sensitive than off-resonant detection using the Stark shift. We present the results of various experimental configurations and a theoretical analysis to illustrate the effectiveness of this multiple level scheme. These results show that this approach allows for the detection of frequencies in a continuous band between resonances with adjacent Rydberg states.

Proximity coupled fed wideband printed magneto–electric dipole antenna

Results are presented fora wideband printed magneto-electric dipole antenna. The printed electric dipole and reflector are separated by an air-gap and is fed with a coaxial transmission line and a printed proximity coupled T-shaped feeding strip. The slot between the electric dipole halves forms the magnetic dipole radiating aperture. This feeding mechanism allows for good impedance matching at adjacent resonances of the electric and magnetic dipoles to achieve wideband operation. The two printed electric dipole halves are DC shorted to the reflector. The results show that this antenna can operate over a wide bandwidth with good gain, stable unidirectional radiation patterns and low cross polarization. The effect of the air-gap height and the relative permittivity of the substrate on which the dipole is printed are investigated. Results show that an optimum air-gap height for a specific substrate permittivity can be determined that will result in a gain with a small variation over the entire impedance bandwidth of the antenna. Simulated as well as measured results are presented for a prototype antenna with a small gain variation and overall dimensions of 1.33λ0 × 1.33λ0 × 0.19λ0. A measured impedance bandwidth of 54% with an average gain of 9.2 dBi is achieved.

A microstrip planar lowpass filter with ultra-wide stopband using hexagonal-shaped resonators

Abstract A microstrip planar lowpass filter with ultra-wide stopband up to 40 GHz is presented. The filter is designed based on four types of hexagonal-shaped resonators, producing multiple transmission zeroes and extending the stopband. The high-impedance transmission line is folded to make the circuit more compact and form the coupling gaps between the adjacent resonators. A pair of folded open stubs are added to enhance the cut-off rate. As a result, an ultra-wide stopband with 23rd-harmonic suppression has been attained. A demonstration filter has been designed and fabricated with 3 dB cut-off frequency of 1.70 GHz. The measured results show that the relative stop bandwidth of the low-pass filter (LPF) is 182% with suppression level of 25 dB, covering 1.85–40 GHz. The functional area size of the filter is 21.50 × 21.70 mm, which corresponds to 0.198λ g × 0.200λ g (λ g is the guided wavelength at 3 dB cut-off frequency).

Design of n-Way Wideband Filtering Power Dividers With Good Port–Port Isolation

In this article, a novel $n$ -way topology is proposed to design a class of multiway wideband filtering power dividers (FPDs). It consists of $n$ -coupled multimode resonators and $n$ resistors. To achieve a wideband filtering response, the stub-loaded multimode resonator is first employed. A good port–port isolation can then be obtained by electrically connecting the original open end of the two half-wavelength stubs of the two adjacent multimode resonators, and amounting a shunt resistor in-between the two adjacent stubs, which is allocated a quarter-wavelength away from the electrical connection point. The frequency responses of power division and isolation are analyzed based on even–odd mode, aiming to carry out theoretical analysis for wideband $n$ -way power dividers. To verify the proposed design method, a prototype three-way wideband FPD and a four-way wideband FPD are designed and fabricated. The simulated and measured results show a good agreement from each other, thus verifying the feasibility of this proposal.

Tuning of subwavelength topological interface states in locally resonant metastructures with shunted piezoelectric patches

We investigate the propagation behavior of the low-frequency topological interface state of the flexural wave in the locally resonant metastructure and analyze the tunability of the sub-wavelength interface states by the piezoelectric shunting circuit. One homogeneous thin beam is periodically attached with local resonant beams, which connect shunted piezoelectric actuators. The folding band obtained by merging two primitive unit cells into one new element can generate a Dirac point below the low-frequency locally resonant bandgap. This folding point is opened to develop one new bandgap originated from the Bragg scattering effect by breaking the mirror symmetry. Then, topological transitions are demonstrated during the distance variation between two adjacent resonances. The interface state’s existence is further confirmed by using steady and transient analysis of the heterostructure composed of two media with different topological properties. Finally, we show the relationship between the interface frequency and the capacitance ratio and research the influence of the distance parameter on the topological interface state. Because of the tunability of elastic waves by the piezoelectric shunting circuit, our design has potential for applications such as energy harvesters, filters, and physical switches.

Demonstration of green and UV wavelength high Q aluminum nitride on sapphire microring resonators integrated with microheaters

We demonstrate a high Q aluminum nitride (AlN) on sapphire microring resonators at green (532 nm) and ultraviolet (UV) (369.5 nm), which are two important wavelengths for sensing and quantum information processing. The quality factors (Q) of these resonators are characterized using integrated microheaters and based on thermo-optic resonance sweeping around those wavelengths for which tunable lasers are typically less available. We measure a record of high intrinsic Q of 147 000 with a propagation loss of 7.3 dB/cm at 532 nm wavelength, and an intrinsic Q of 25 500 with a propagation loss of 60.4 dB/cm at UV 369.5 nm wavelength. We also investigate the thermal crosstalk between the adjacent resonators when temperature change is applied by the microheater of one of the resonators on the same chip. A large thermal crosstalk and resonance shift are observed on other microring resonators even at millimeter(s) distance away from a microheater. This study provides further insight on the functionalities and capabilities of this promising integrated photonic platform for the ultraviolet (UV) and visible range.

A Tunable Ferrite Isolator for 30 GHz Millimeter-Wave Applications

In this article, a tunable ferrite-loaded isolator working at millimeter-wave (mm-Wave) frequency for applications in multi-function systems is presented. The device is based on nonreciprocal coupling between a ferrite slab and a half-mode substrate-integrated waveguide (HMSIW). The HMSIW offers a compact design and, more important here, the ability of energy coupling to adjacent resonators. The ferrite slab is placed outside the HMSIW, close to the H-wall symmetry of the HMSIW, providing the possibility of movement for the ferrite slab and low insertion loss of the transmission mode. Any change in the position of the ferrite slab changes the propagation constant of the mode traveling across the ferrite-coupled HMSIW, which, consequently, results in different center frequencies of the isolation. To the best of our knowledge, the proposed design is one of the first tunable isolators for such a high frequency. Despite previously reported isolators that require a strong magnetic bias field for mm-Wave range applications, the proposed isolator requires a relatively low magnetic bias (less than 20 KA/m), which is provided by a small and lightweight permanent magnet. The 10 dB isolation bandwidth of the design is about 2 GHz varying from 34 to 37 GHz based on the position of the ferrite slab. The insertion loss of the device is measured between 2 and 3 dB.

A Novel 1.7–2.85-GHz Filtering Crossover With Independently Tuned Channel Passbands and Reconfigurable Filtering Power-Dividing Function

In this article, a novel filtering crossover with independently tuned channel passbands and reconfigurable filtering power divider (PD) function based on evanescent-mode cavity (EVA) is proposed for the first time. It consists of four substrate-integrated-waveguide (SIW) EVA resonators loaded with piezoelectric actuators for frequency tuning. Four sets of varactors are used between adjacent resonators for control of interstage coupling, whereas four sets of varactors are inserted between ports and resonators for input-output matching. By controlling resonant frequencies of the EVA resonators and coupling coefficients between adjacent resonators, the passbands of the two orthogonal channels in the filtering crossover can be independently tuned in either synchronous or asynchronous fashion within the frequency range of 1.7-2.81 GHz. Meanwhile, by detuning the resonant frequency of one resonator in the crossover, the proposed structure can be reconfigured to become a three-port filtering PD with continuous frequency tuning covering 1.7-2.85 GHz. Moreover, with the independently tuned feature, a filter with reconfigurable filtering PD and diplexer functions can be easily achieved by attaching the proposed crossover to an external matching junction. Several prototypes were given to demonstrate the proposed techniques. Good agreement is obtained between simulated and measured results.

Microstrip Quazi-Elliptic Bandpass Filter With Two Pairs of Antiparallel Mixed-Coupled SIRs

An analysis of the second-order mixed-coupled bandpass filter (BPF) of a general form is carried out. The resonators in this BPF are presented by a resonant frequency $f_{0}$ and a susceptance slope parameter $b$ . The position of the transmission zero (TZ) generated by the mixed coupling is determined. A correspondence is established between the mixed coupling representation as the sum of magnetic $K_{\mathrm{ m}}$ and electric $K_{\mathrm{ e}}$ components and the linear representation form $m (\Omega) = m_{0} {-} a \,\,\Omega $ . It is shown that the slope of the frequency dependence $m(\Omega $ ) is negative. The conditions for equidistant arrangement of two TZs in BPF with mixed couplings between adjacent resonators are formulated. A fourth-order microstrip quazi-elliptic BPF with two pairs of antiparallel mixed-coupled stepped-impedance resonators (SIRs) is proposed. It reduces the parasitic interaction between nonadjacent resonators and makes it possible to obtain the required frequency responses more accurately. The results of the measurements and simulation are presented.

Millimeter-Wave Dual-Band Bandpass Filter With Large Bandwidth Ratio Using GaAs-Based Integrated Passive Device Technology

In this letter, a millimeter-wave (mm-wave) dual-band bandpass filter is proposed with large bandwidth ratio by using gallium arsenide (GaAs)-based integrated passive device (IPD) technology. To realize small chip size, one dual-mode on-chip resonator is designed by using quasi-lumped capacitors and microstrip lines. In addition, multiple transmission zeroes are generated by further introducing both the electric and magnetic couplings between adjacent resonators. To realize large bandwidth ratio of two passbands, the external quality factors are investigated at both passband, and can be independently controlled. For demonstration, a 28-/50-GHz dual-band bandpass filter is designed, fabricated, and measured. The fractional bandwidth ratio is 7.8, which is much larger than the reported on-chip filters. Meanwhile, very low insertion loss of 0.58-dB is realized for the lower passband at 28 GHz, indicating the proposed dual-band bandpass filter a promising application in mm-wave wireless systems.

Low‐profile millimetre‐wave wideband microstrip antenna with parasitic patch arrays

A millimetre-wave low-profile wideband microstrip antenna is proposed. To widen impedance bandwidth and achieve stable large gain simultaneously, coplanar parasitic patch arrays are arranged on both sides of a microstrip patch fed by a coaxial probe. Double slots are etched on the microstrip patch to reduce H-plane cross-polarization levels. Zero-phase-reflection analysis with Floquet-port model is proposed to predict resonant frequency of the parasitic patch arrays. Resonance modes excited is verified according to input impedance with an ideal probe. Two adjacent broadside resonances respectively dominated by the quasi-TM10 mode of the microstrip patch and quasi-TM30 of the parasitic patch array are excited in turn. The proposed antenna with a dimension of 1.06 × 1.06 × 0.024 λ03 (λ0 is the wavelength of 29 GHz in free space) realizes 15% (27–31.35 GHz) impedance bandwidth for |S11| ≤ −10 dB. Realized peak gain is up to 9.26 dBi and 2-dB gain bandwidth is 15.7%. H-plane cross-polarization levels within 3-dB beamwidth are less than −14 dB, and back radiation levels are less than −17.9 dB.

Dynamic Observation of Topological Soliton States in a Programmable Nanomechanical Lattice.

Topological soliton states, existing in the topological structures with edge defect or interface defect, are usually studied under steady state. Here, we experimentally observe the dynamic processes of the generation and the extinction of such soliton states in the Su-Schrieffer-Heeger model. The different topological structures are implemented on a programmable nanomechanical lattice, consisting of eight adjacent string resonators which are parametrically coupled by manipulation voltages. Moreover, the beating and localization behaviors at different topological interfaces are also observed in the same device. These results explicitly exhibit the dynamic processes of topological soliton states, which reveal real potential toward integrated multifunctional topological materials.

Dynamic Free-Spectral-Range Measurement for Fiber Resonator Based on Digital-Heterodyne Optical Phase-Locked Loop

We propose a novel scheme, based on digital-heterodyne optical phase-locked loop with whole-fiber circuit, to dynamically measure the free-spectral-range of a fiber resonator. The optical phase-locked loop is established with a differential frequency-modulation module consists of a pair of acousto-optic modulators. The resonance-tracking loop is derived with the Pound-Drever-Hall technique for locking the heterodyne frequency of the OPLL on the frequency difference between adjacent resonance modes. A stable locking accuracy of about 7 × 10?9 and a dynamic locking accuracy of about 5 × 10?8 are achieved with the FSR of 8.155 MHz, indicating a bias stability of the resonator fiber optic gyro of about 0.1?/h with 10 Hz bandwidth. In addition, the thermal drift coefficient of the FSR is measured as 0.1 Hz/?C. This shows remarkable potential for realizing advanced optical measurement systems, such as the resonant fiber optic gyro, and so on.