Resonant Shunt Research Articles

Vibration and wave propagation attenuation for metamaterials by periodic piezoelectric arrays with high-order resonant circuit shunts

Beam or plate metamaterials with periodic piezoelectric arrays have attracted more and more attention in recent years for wave propagation attenuation and the corresponding vibration reduction. Conventional designs use resistive shunt (R-shunt) and resistor-inductor shunt (RL-shunt). An innovative metamaterial with a high-order resonant shunt circuit is proposed and investigated for vibration and wave propagation attenuation in this paper. The proposed high-order resonant shunt circuit can introduce two local resonances in series around the tuning frequency to broaden the attenuation bandwidth, or can create two separate resonances to achieve two separate bandgaps. Finite element modeling of the beam metamaterial with wave propagation and vibration in the transverse direction is established. Simulations have been conducted to compare the vibration attenuation performances among R-shunt, RL-shunt, and the proposed high-order shunt. An impedance-based method has been presented for the parameter design of electrical components in the proposed high-order shunt for bandgaps at two desired frequencies.

Tuning of a vibration absorber with shunted piezoelectric transducers

In order to reduce structural vibrations in narrow frequency bands, tuned mass absorbers can be an appropriate measure. A quite similar approach which makes use of applied piezoelectric elements, instead of additional oscillating masses, are the well-known resonant shunts, consisting of resistances, inductances, and possibly negative capacitances connected to the piezoelectric element. This paper presents a combined approach, which is based on a conventional tuned mass absorber, but whose characteristics can be strongly influenced by applying shunted piezoceramics. Simulations and experimental analyses are shown to be very effective in predicting the behavior of such electromechanical systems. The vibration level of the absorber can be strongly attenuated by applying different combinations of resistant, resonant, and negative capacitance shunt circuits. The damping characteristics of the absorber can be changed by applying a purely resistive or resonant resistant shunt. Additionally, the tuning frequency of the absorber can be adapted to the excitation frequency, using a negative capacitance shunt circuit, which requires only the energy to supply the electric components.

Directionality of wave propagation and attenuation in plates with resonant shunting arrays

This article proposes an analytical method to evaluate the propagation constant in arbitrary direction in the plate with shunting arrays, which can circumvent the complicated transcendental eigenvalue problem. Based on this method, the directionality of waves propagating or decaying in the plate with arrays of resonant shunts is examined, including directionality of attenuation constant, location of band gaps, and group velocity in pass band. Moreover, the theoretical results are verified by simulation in well-accepted commercial finite element software.

Locally resonant band gaps achieved by equal frequency shunting circuits of piezoelectric rings in a periodic circular plate

This work presents an investigation on vibration transmission in a circular thin plate consisting of metal rings and piezoelectric rings arrayed periodically. Each piezoelectric ring is linked to an independent resistive–inductive (RL) resonant shunting circuit. For a periodic rectangular piezoelectric plate, equal inductances are commonly used in resonant shunting circuits. However, for the circular one, the locally resonant (LR) band gap (BG) cannot be formed by shunting circuits with equal inductances, because different periodic cell has a different capacitance. Instead of equivalent inductance circuits, the equal frequency shunting circuits are employed to tune the resonance frequency of each circuit into the same, thus an integrating LR BG is obtained. A transfer matrix method is used to calculate transmission factor in the low frequency range. The theoretical model is verified by finite element method (FEM). The impact of geometric and circuit parameters on the properties of the LR BG and vibration attenuation band (VAB) has also been analyzed.

Transversal Asymmetry in Periodic Leaky-Wave Antennas for Bloch Impedance and Radiation Efficiency Equalization Through Broadside

This paper demonstrates that unit cell asymmetry with respect to the transversal axis -or transversal asymmetry- is an essential design parameter in periodic leaky-wave antennas (P-LWAs). Specifically, it shows that transversal asymmetry can be leveraged to fully and systematically solve the well-known radiation degradation of P-LWAs at broadside, where it provides both open-stopband closure and efficiency equalization. The problem is addressed via a generic equivalent circuit model composed of a series resonator, a shunt resonator and ideal transformers for modeling asymmetry by a single and simple parameter, namely the transformation ratio. Once the series and shunt frequencies have been balanced (frequency-balancing), equalization is ensured by adjusting the degree of asymmetry in the unit cell so to match the at-broadside Bloch impedance to the off-broadside Bloch impedance. This equalization condition is referred to as quality factor balancing ( Q-balancing) and it is related to the Heaviside condition (distortionless propagation) in homogeneous transmission lines. Based on this theory, optimization schemes for employing commercial fullwave eigenmode and drivenmode solvers are proposed to design unit cells with equalized efficiencies. Finally, two examples of P-LWAs are presented, a composite right/left-handed (CRLH) P-LWA and a series-fed coupled patch (SFCP) P-LWA, and verified to fully confirm the predictions of the theory obtained by circuit modeling.

Piezoelectric Shunt Vibration Damping of Structural-Acoustic Systems: Finite Element Formulation and Reduced-Order Model

For noise and vibration attenuation, various approaches can be employed depending on the frequency range to attenuate. Generally, active or passive piezoelectric techniques are effective in the low-frequency range, while dissipative materials, such as viscoelastic or porous treatments, are efficient for higher-frequency domain. In this work, a reduced-order model is developed for the approximation of a fully coupled electromechanical-acoustic system using modal projection techniques. The problem consists of an elastic structure with surface-mounted piezoelectric patches coupled with a compressible inviscid fluid. The piezoelectric elements, connected with resonant shunt circuits, are used for the vibration damping of the coupled system. Numerical examples are presented in order to illustrate the accuracy and the versatility of the proposed reduced-order model, especially in terms of prediction of attenuation.

Common-mode suppressed differential bandpass filter based on open complementary split ring resonators fabricated in microstrip technology without ground plane etching

A differential (or balanced) bandpass filter based on open complementary split ring resonators (OCSRRs) coupled through admittance inverters is presented in this article. Pairs of OCSRRs are symmetrically placed in a mirror configuration between the strips of the differential line and are modeled by means of two series connected parallel resonators. For the differential (odd) mode, there is a virtual ground at the connecting plane between the OCSRR pairs, and the structure is roughly described by the canonical model of a bandpass filter, consisting of a cascade of shunt resonators coupled through admittance inverters. It is demonstrated that, through a proper design of the OCSRR stages, the common mode noise in the vicinity of the differential filter pass band can be efficiently suppressed. Due to the differential mode operation of the filter, it is not necessary to incorporate metallic vias to ground the OCSRRs. Moreover, as compared to other differential filters based on OCSRRs, defected ground structures are not present in the proposed filters. To illustrate the potential of the approach, two balanced bandpass filters are designed, fabricated, and characterized. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:910–916, 2014

Compact CRLH Asymmetric-CPS Resonant Antenna With Frequency Agility

A compact, uniplanar composite right/left-handed transmission line (CRLH TL) resonant antenna with frequency agility is proposed based on the asymmetric coplanar strip (ACPS). First, it is shown that a capacitor as the termination for an unbalanced CRLH ACPS is needed for excitation of an anti-resonance within the frequency range between the zeroth-order series and shunt resonances. The design formula to estimate the value of the termination capacitance for a given resonant frequency is derived as well. By utilizing a varactor diode as the termination, the termination capacitance can be controlled by changing its bias voltage, and the resonance of the antenna can thus be tuned between the two zeroth-order resonant frequencies. For verification, a prototype antenna was fabricated and tested. It has a continuously tunable resonant frequency between 2.15 GHz and 2.8 GHz as the bias voltage is adjusted in between 4 V and 22 V. When tuned to resonate at different frequencies in between the two zeroth-order resonances, the antenna still exhibits similar slot-like radiation pattern and stable peak gain and radiation efficiency owing to the same resonant mechanism in the frequency range.

ICP, BMI, Surgical Repair, and CSF Diversion in Patients Presenting With Spontaneous CSF Otorrhea

To assess intracranial pressure (ICP), body mass index (BMI), surgical repair, and cerebrospinal fluid (CSF) diversion in patients presenting with spontaneous CSF otorrhea. Retrospective series review. Tertiary referral center. Thirty-two patients were treated surgically from 2004 to 2013 for spontaneous CSF otorrhea by the principal investigators. Patients with a history of chronic ear disease and cholesteatoma, previous mastoid surgery, head trauma, or iatrogenic injury were excluded. Average age was 56 years. Twenty-two patients (69%) were female. Middle fossa repair, transmastoid repair, lumbar puncture, V-P shunt, L-P shunt, and magnetic resonance imaging. Patients underwent middle fossa or transmastoid repair of tegmen defects. Intracranial pressures were determined with lumbar puncture at time of surgical repair or shortly after surgery. CSF diversion procedures were performed in patients who were found to have elevated ICP, which was not controlled medically, presented with recurrent leak or had ICP of 25 cm or greater of H2O. Preoperative BMI was calculated. Thirty-two patients underwent 37 operations. Average BMI was 35.0 kg/m2 (median, 34.7; range, 18.7-53.2 kg/m2). There were 21 repairs on the left and 16 on the right. The majority underwent a middle fossa craniotomy for repair (27/32). Two patients had bilateral repairs. Three patients (8%) underwent revision surgery, of which, 2 had untreated intracranial hypertension (ICP 24.5 and 24 cm H2O). ICP measurements were available for 29 patients. The mean ICP was 23.4 cm H2O (median, 24; range, 13-36 cm H20). Twenty-two patients (69%) had ICP of 20 cm or greater of H20; of those, 13 had an ICP of 25 cm or greater of H20. Seventeen patients (53%) underwent CSF diversion procedures. Our findings of elevated ICP and BMI in patients presenting with spontaneous CSF otorrhea are consistent with previous reports in the literature. The percentage of patients that underwent CSF diversion procedures was high at 53% and represents an aggressive stance in managing elevated ICP in a population that may be at risk for subsequent leaks.

Essentially nonlinear piezoelectric shunt circuits applied to mistuned bladed disks

An essentially nonlinear piezoelectric shunt circuit is proposed for the practical realization of nonlinear energy sink, and then applied to a mistuned bladed disk for blade vibration reduction. First, the global dynamics of a single degree-of-freedom linear mechanical oscillator, coupled to an essentially nonlinear shunted piezoelectric attachment, is studied. Under certain conditions, the nonlinear targeted energy transfer, i.e. a fast, passive energy transfer from the mechanical oscillator to the nonlinear attachment is observed. A numerical method, referred to as the variable-coefficient harmonic balance method, is developed to calculate quasi-periodic responses arising in the electromechanical system under harmonic forcing. Characterized by the nonexistence of a resonance frequency, the essentially nonlinear shunt circuit is able to work robustly over a broad frequency band with a smaller inductance requirement compared with the linear resonant shunt circuit. The application of piezoelectric shunt damping to simplified blade–disk structures is then taken into consideration. Shunted piezoelectrics are attached onto the disk surface in our damping strategy in order to reduce blade vibrations. Essential nonlinearity is also introduced into the piezoelectric shunted bladed disk system. Since the piezoelectric-based nonlinear energy sink is not a priori tuned to any specific frequency, a sound damping performance is achieved when blades become inevitably mistuned.

A HMSIW Circularly Polarized Leaky-Wave Antenna With Backward, Broadside, and Forward Radiation

A miniaturized frequency-scanning leaky-wave antenna (LWA) with circular polarization (CP) and backward-broadside-forward radiation is presented. Half-mode substrate integrated waveguide (HMSIW) in combination with interdigital capacitors (IDCs) is utilized in order to achieve a composite right/left-handed leaky-wave structure. Ramp-shaped slots are introduced as interdigital capacitors. Using this structure, the balanced condition (in which series and shunt resonances are equal) can be obtained for the unit-cell. As a result, wide bandwidth of 7.4-13.5 GHz with continuous angular scanning of ~ -70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to 70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> is achieved. The axial ratio in the direction of the main beam is lower than 3.1. The performance of the antenna is measured, and close agreement between the simulation and measurement is observed.

Wideband Bandpass Filters With SAW-Filter-Like Selectivity Using Chip SAW Resonators

Bandpass filters with surface acoustic wave (SAW)-filter-like selectivity and much wider bandwidth compared to conventional SAW filters are presented. The proposed topology consists of SAW resonator networks and parallel coupled lines. Each ladder type resonator network has a series resonator and two shunt resonators to define the upper and lower cutoff frequencies and realize the sharp passband selectivity. Analysis of the proposed SAW resonator network and a comparison with a traditional ladder type SAW filter is provided. Two filters are designed, fabricated, and measured using chip SAW resonators and microstrip coupled lines on Rogers RO4003C. As the available SAW resonators are discrete, they are connected together using 1-mil bond wires to form the SAW resonator network. The resonators are also wire bonded to the coupled lines and ground patch. The bandwidth of the two filters is 10.5% and 17%, respectively, which is much wider than conventional SAW filters with a bandwidth of a few percent. An analysis is provided for the bulk wave effects, ripples due to finite transducer, gratings of resonators, and second-order effects from series and parallel resonators, which cause deterioration of the passband performance. The impact of bond wire inductance and parasitic coupling, which cause spurious responses at the stopbands, are also discussed.

Independent modal resonant shunt for multimode vibration control of a truss-cored sandwich panel

To realize multimode vibration control of a truss-cored sandwich panel, an independent modal resonant shunt control method is proposed in this paper. In this method, each piezoelectric stack transducer is connected to a single resonant shunt which is tuned to control the vibration of a single mode, and the location of the transducer is optimized to get a maximal electromechanical coupling with this mode. It is found that the optimal values of the resistance and inductance can not be determined by using a single-mode model of the structure, and thus a practical optimization method is employed to optimize the resonant shunt, which is verified with numerical simulation. The result shows that this method can add significant damping ratio to the controlled modes, and the resonant shunt circuits of different modes have no effect on each other. Finally the control effect of resonant shunt is compared with viscoelastic damper. It is indicated that the parameters of the resonant shunt can be tuned to get better effect.

Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches.

Dual-Functional Energy-Harvesting and Vibration Control: Electromagnetic Resonant Shunt Series Tuned Mass Dampers.

This paper proposes a novel retrofittable approach for dual-functional energy-harvesting and robust vibration control by integrating the tuned mass damper (TMD) and electromagnetic shunted resonant damping. The viscous dissipative element between the TMD and primary system is replaced by an electromagnetic transducer shunted with a resonant RLC circuit. An efficient gradient based numeric method is presented for the parameter optimization in the control framework for vibration suppression and energy harvesting. A case study is performed based on the Taipei 101 TMD. It is found that by tuning the TMD resonance and circuit resonance close to that of the primary structure, the electromagnetic resonant-shunt TMD achieves the enhanced effectiveness and robustness of double-mass series TMDs, without suffering from the significantly amplified motion stroke. It is also observed that the parameters and performances optimized for vibration suppression are close to those optimized for energy harvesting, and the performance is not sensitive to the resistance of the charging circuit or electrical load.

Compact CRLH CPW Antennas Using Novel Termination Circuits for Dual-Band Operation at Zeroth-Order Series and Shunt Resonances

A series of termination circuits for unbalanced composite right/left-handed transmission lines (CRLH TLs) are proposed to enable simultaneous excitation of the zeroth-order series and shunt resonances. The proposed termination circuits are very simple and consist merely of a capacitor or inductor in series/parallel with a parallel/series LC tank. Their operational mechanisms are explained in terms of the equivalent circuit models for CRLH TLs at the two zeroth-order resonances, which can also be used to justify the absence of one of the two zeroth-order resonances in conventional open- or short-ended CRLH TLs. Design formulas to estimate the element values of the termination circuits are derived, and some design considerations are discussed as well. Then, the proposed termination circuits are connected to unbalanced CRLH coplanar waveguides (CPWs) to realize two dual-band compact zeroth-order resonator (ZOR) antennas. Unlike conventional dual- or multi-band ZOR antennas formed by open- or short-ended CRLH TLs, in which only one of the zeroth-order resonances can be excited, our proposed ZOR antennas can operate simultaneously at the zeroth-order series and shunt resonances. It is demonstrated that the proposed antennas have similar input impedance responses, slot-like radiation patterns, and peak gains within the two bands. The antenna size is very compact (of about at the upper resonance) since both designs are formed by only two CRLH CPW unit cells.

Differential Bandpass Filter With Common-Mode Suppression Based on Open Split Ring Resonators and Open Complementary Split Ring Resonators

Differential (balanced) microstrip bandpass filters (BPFs) implemented by combining open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs) are proposed. The OSRRs are series connected in both strips of the differential line, whereas the OCSRRs are paired face-to-face and connected between both line strips in a symmetric configuration. For the differential mode, the OCSRRs are virtually connected to ground and the structure can be modeled, to a first-order approximation, by a cascade of series resonators (OSRRs) alternating with shunt resonators (OCSRRs), i.e., the canonical circuit model of a BPF. These filters have the ability to suppress the common mode by properly adjusting the metallic area surrounding the OCSRRs. An order-3 balanced Chebyshev BPF is designed and fabricated to illustrate the possibilities of the approach. The filter does not require vias (contrary to previous single-ended microstrip BPFs based on OSRRs and OCSRRs), filter dimensions are small, and the common mode is efficiently suppressed with more than 20 dB rejection within the differential filter pass band.

Correspondence - Design of ladder-type SAW/BAW

This paper describes the design of RF SAW/ BAW filters with constant group delay. The band-pass LC filter is designed based on the traditional Bessel filter design. Then, LC resonators in the filter are replaced by SAW/BAW resonators with finite capacitance ratio γ. Finite γ generates passband ripples in the group delay. However, it is shown the ripples can be suppressed by optimal design of the SAW/BAW resonators. Norton's first transform is also applied to the designed filter to reduce variation of resonator shunt capacitances. Finally, extremely flat group delay with deviation of 4 ns over the frequency range of ±20 MHz at the center frequency of 1 GHz is theoretically demonstrated.

Wave propagation and attenuation in plates with periodic arrays of shunted piezo-patches

Periodic arrays of shunted piezoelectric patches are employed to control the wave propagation in a thin plate. The performance is characterized through the application of finite element method and Bloch theorem. This article proposes an effective approach to gain the dispersion properties of the periodically shunted plate in any directions from the solutions of transcendental eigenvalue problems. The results show that resistive shunts can tune the location and attenuation constants of the Bragg gap, while the internal resonances of resonant shunting system split the dispersion curves and form a locally resonant band gap. Moreover, the Bragg gap is directional, whose width varies enormously with directions. However, the locally resonant gap almost keeps the same in different directions, i.e., the gap is complete. Also, the influences of different shunting parameters to the band gaps are investigated in detail.

Development and beam test of a continuous wave radio frequency quadrupole accelerator

The front end of any modern ion accelerator includes a radio frequency quadrupole (RFQ). While many pulsed ion linacs successfully operate RFQs, several ion accelerators worldwide have significant difficulties operating continuous wave (CW) RFQs to design specifications. In this paper we describe the development and results of the beam commissioning of a CW RFQ designed and built for the National User Facility: Argonne Tandem Linac Accelerator System (ATLAS). Several innovative ideas were implemented in this CW RFQ. By selecting a multisegment split-coaxial structure, we reached moderate transverse dimensions for a 60.625-MHz resonator and provided a highly stabilized electromagnetic field distribution. The accelerating section of the RFQ occupies approximately 50% of the total length and is based on a trapezoidal vane tip modulation that increased the resonator shunt impedance by 60% in this section as compared to conventional sinusoidal modulation. To form an axially symmetric beam exiting the RFQ, a very short output radial matcher with a length of $0.75\ensuremath{\beta}\ensuremath{\lambda}$ was developed. The RFQ is designed as a 100% oxygen-free electronic (OFE) copper structure and fabricated with a two-step furnace brazing process. The radio frequency (rf) measurements show excellent rf properties for the resonator, with a measured intrinsic $Q$ equal to 94% of the simulated value for OFE copper. An ${\mathrm{O}}^{5+}$ ion beam extracted from an electron cyclotron resonance ion source was used for the RFQ commissioning. In off-line beam testing, we found excellent coincidence of the measured beam parameters with the results of beam dynamics simulations performed using the beam dynamics code TRACK, which was developed at Argonne. These results demonstrate the great success of the RFQ design and fabrication technology developed here, which can be applied to future CW RFQs.