Resonance Frequency Of Fundamental Mode Research Articles

Young's modulus and corresponding orientation in β-Ga2O3 thin films resolved by nanomechanical resonators

We report on the nondestructive measurement of Young's modulus of thin-film single crystal beta gallium oxide (β-Ga2O3) out of its nanoscale mechanical structures by measuring their fundamental mode resonance frequencies. From the measurements, we extract the Young's modulus in the (100) plane, EY,(100) = 261.4 ± 20.6 GPa, for β-Ga2O3 nanoflakes synthesized by low-pressure chemical vapor deposition (LPCVD), and in the [010] direction, EY,[010] = 245.8 ± 9.2 GPa, for β-Ga2O3 nanobelts mechanically cleaved from bulk β-Ga2O3 crystal grown by the edge-defined film-fed growth (EFG) method. The Young's moduli extracted directly on nanomechanical resonant device platforms are comparable to theoretical values from first-principle calculations and experimentally extracted values from bulk crystal. This study yields important quantitative nanomechanical properties of β-Ga2O3 crystals and helps pave the way for further engineering of β-Ga2O3 micro/nanoelectromechanical systems (M/NEMS) and transducers.

E-textile slot antenna with spurious mode suppression and low SAR for medical wearable applications

In this paper, electronic textile (E-textile) antenna design, with spurious mode suppression and low specific absorption rate (SAR), at a nearest distance of 1 mm from on-body phantom is investigated. The textile antenna is designed using a denim substrate material with conductive patch as a radiating element. The slots are introduced on the patch for spurious mode suppression so that external radio frequency components can be integrated with textile antenna without hampering the efficiency of the body area network system. The measured bandwidth of the proposed antenna is 100 MHz (2.39–2.49 GHz) in the 2.45 GHz ISM frequency band with broadside radiation pattern. The radiation pattern at spurious mode is suppressed by 5 dB without any change in the resonance frequency of fundamental mode. Besides, considering human safety for wearable devices, the SAR values average over 1 g of tissue are 0.208, 0.106 and 0.087 W/Kg at a distance of 1, 3 and 5 mm from on-body phantom, respectively.

Electromechanical coupling and motion transduction in β -Ga2O3 vibrating channel transistors

We report on device physics modeling, assisted by experimental measurement results, for all-electronic transduction of resonant electromechanical motion of nanoscale β-Ga2O3 vibrating channel transistors (VCTs), including both direct readout of high frequency transmission current (without frequency down-conversion) and frequency modulation (FM) down-conversion techniques. The β-Ga2O3 VCTs under consideration have fundamental mode resonance frequencies at ∼25 MHz–1 GHz, with quality factors (Qs) of ∼100–5000 and transconductance gm at ∼0.2 nS–5 μS. In analysis of signal transduction with varying device parameters, the transistor's gate trench depth z0 and transconductance gm play key roles in improving the electromechanical coupling and device performance. Reduction of trench depth z0 can engender a major enhancement in readout current. Reducing channel thickness h and increasing channel length L can improve the readout current while downshifting the resonance frequency at the same time. We design β-Ga2O3 VCT with a suspended modulation doped field effect transistor structure for efficient operation in the GHz range. This study paves the way for future engineering of all-electronic transduction and integration of high frequency β-Ga2O3 resonators on chip with β-Ga2O3 electronics and optoelectronics.

Quartz-Enhanced Photoacoustic Detection of Ethane in the Near-IR Exploiting a Highly Performant Spectrophone

In this paper the performances of two spectrophones for quartz-enhanced photoacoustic spectroscopy (QEPAS)-based ethane gas sensing were tested and compared. Each spectrophone contains a quartz tuning fork (QTF) acoustically coupled with a pair of micro-resonator tubes and having a fundamental mode resonance frequency of 32.7 kHz (standard QTF) and 12.4 kHz (custom QTF), respectively. The spectrophones were implemented into a QEPAS acoustic detection module (ADM) together with a preamplifier having a gain bandwidth optimized for the respective QTF resonance frequency. Each ADM was tested for ethane QEPAS sensing, employing a custom pigtailed laser diode emitting at ~1684 nm as the exciting light source. By flowing 1% ethane at atmospheric pressure, a signal-to-noise ratio of 453.2 was measured by implementing the 12.4 kHz QTF-based ADM, ~3.3 times greater than the value obtained using a standard QTF. The minimum ethane concentration detectable using a 100 ms lock-in integration time achieving the 12.4 kHz custom QTF was 22 ppm.

Acoustic Coupling between Resonator Tubes in Quartz-Enhanced Photoacoustic Spectrophones Employing a Large Prong Spacing Tuning Fork.

A theoretical model describing the acoustic coupling between two resonator tubes in spectrophones exploiting custom-made quartz tuning forks (QTFs) is proposed. The model is based on an open-end correction to predict the optimal tube length. A calculation of the sound field distribution from one tube exit allowed for the estimation of the optimal radius as a function of the QTF prong spacing and the sound wavelength. The theoretical predictions have been confirmed using experimental studies employing a custom QTF with a fundamental flexural mode resonance frequency of 15.8 kHz and a quality factor of 15,000 at atmospheric pressure. The spacing between the two prongs was 1.5 mm. Spectrophones mounting this QTF were implemented for the quartz-enhanced photoacoustic detection of water vapor in air in the mid-infrared spectral range.

Tuning forks with optimized geometries for quartz-enhanced photoacoustic spectroscopy.

We report on the design, realization, and performance of novel quartz tuning forks (QTFs) optimized for quartz-enhanced photoacoustic spectroscopy (QEPAS). Starting from a QTF geometry designed to provide a fundamental flexural in-plane vibrational mode resonance frequency of ~16 kHz, with a quality factor of 15,000 at atmospheric pressure, two novel geometries have been realized: a QTF with T-shaped prongs and a QTF with prongs having rectangular grooves carved on both surface sides. The QTF with grooves showed the lowest electrical resistance, while the T-shaped prongs QTF provided the best photoacoustic response in terms of signal-to-noise ratio (SNR). When acoustically coupled with a pair of micro-resonator tubes, the T-shaped QTF provides a SNR enhancement of a factor of 60 with respect to the bare QTF, which represents a record value for mid-infrared QEPAS sensing.

Investigation of higher order modes excitation through F-shaped slot in rectangular dielectric resonator antenna for wideband circular polarization with broadside radiation characteristics

In this article, a wideband circularly polarized rectangular dielectric resonator antenna (RDRA) with broadside radiation characteristics has been proposed. By using modified ground plane having an F-shaped slot, the proposed structure able to generates three sets of modes i.e., fundamental as well as higher order modes. To obtained circular polarization, an orthogonal mode (TE113) in the RDRA has been generated by using the F-shaped slot on the modified ground plane. The resonance frequency of fundamental mode (TE111) in the rectangular dielectric resonator (DR) has been calculated by using dielectric waveguide model method. The same has been confirmed through E-field distribution in RDRA. Here, wide axial ratio (AR) bandwidth of the proposed antenna is due to the generation of and modes. It is observed that input impedance bandwidth has been broadening with a pair of excited modes ( and modes) in the proposed antenna structure. All these modes have been excited and merged to form a wide input impedance bandwidth and wide AR bandwidth of the designed antenna. The proposed antenna shows measured input reflection coefficient (S11 < −10 dB) of 50.55% and measured AR bandwidth (AR < 3 dB) of 14.28%. The designed antenna shows left-handed circular polarization in broadside direction and offering an average gain and radiation efficiency of 4.29 dBic and 92.22% respectively.

Magnetic field response of doubly clamped magnetoelectric microelectromechanical AlN-FeCo resonators

Magnetoelectric (ME) cantilever resonators have been successfully employed as magnetic sensors to measure low magnetic fields; however, high relative resolution enabling magnetometry in high magnetic fields is lacking. Here, we present on-chip silicon based ME microelectromechanical (MEMS) doubly clamped resonators which can be utilized as high sensitivity, low power magnetic sensors. The resonator is a fully suspended thin film ME heterostructure composed of an active magnetoelastic layer (Fe0.3Co0.7), which is strain coupled to a piezoelectric signal/excitation layer (AlN). By controlling uniaxial stress arising from the large magnetoelastic properties of magnetostrictive FeCo, a magnetically driven shift of the resonance frequency of the first fundamental flexural mode is observed. The theoretical intrinsic magnetic noise floor of such sensors reaches a minimum value of 35 pT/Hz. This approach shows a magnetic field sensitivity of ∼5 Hz/mT in a bias magnetic field of up to 120 mT. Such sensors have the potential in applications required for enhanced dynamic sensitivity in high-field magnetometry.

Size-dependent resonance frequencies of longitudinal vibration of a nonlocal Love nanobar with a tip nanoparticle

Axial free vibration of a nanobar carrying a nanoparticle is studied based on the nonlocal elasticity theory and Love’s assumption. By considering inertia of radial motion during longitudinal vibration, a governing equation for a nanobar–mass oscillation system is derived via Hamilton’s principle. An exact frequency equation is obtained and an approximate simple expression for the fundamental-mode resonance frequency is given. The size effect of the resonance frequencies is elucidated. The classical Love bar theory and the nonlocal bar theory can be recovered from two special cases by setting the nonlocal parameter and Poisson’s ratio to zero, respectively. Numerical examples are given to show the influence of the nonlocal scaling parameter and attached mass on the resonance frequencies and frequency shifts. Identification formulas for estimating the mass of an attached nanoparticle and predicting the nonlocal parameter are established through the frequency change.

A phase noise reduction method in microwave oscillator using a high-Q transmission line loaded with active SIW resonator

In this letter, a transmission line (TL) loaded with active circular substrate integrated waveguide (SIW) resonator is presented and used in microwave oscillator to reduce phase noise. By compensating the resonance loss in SIW cavity using coupling negative resistance method in active resonator, the TL loaded with active SIW resonator exhibits a sharp reflective property at the fundamental mode resonance frequency which is suitable for series feedback oscillator. The simulated loaded Q-factor of the proposed TL achieves 379. To validate this method, X-band oscillators using TL loaded with active and passive SIW resonator are designed and implemented. The measured results show that the oscillator base on active SIW resonator exhibits a low phase noise of −128.75 dBc/Hz at 1 MHz offset frequency from 11.01 GHz carrier, which is 9 dB better than the oscillator based on passive SIW resonator. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:221–225, 2016

Dielectric Properties Measurement of Biological Materials Using Non-Destructive Sensors

The authors' research work has for objective the study of a sensor with planar resonator for applications in the non-destructive control. In this context, two approaches were defined. In a first part, a conception, a modeling, a simulation with commercial software (HFSS, CST), a realization and measurements were treated on Rectangular Patch Resonators (RPR). The proposed theoretical analysis is based on the Moment Method (MoM) via the Galerkin's approach, in which three types of entire domain basis functions are used to expand the patch currents. While, the first two types of basic functions involve a set of sinusoidal cavity modes without edge conditions (sbf-wo-ec) and with edge conditions (sbf-w-ec), and in order to incorporate the edge conditions (cp-ec), the third one consists of Chebyshev polynomials combinations with weighting factors. These last ones as well as the Green Dyadic spectral functions are efficiently implanted with compact Fortran 90 codes. Two EM commercial software HFSS and CST was used to validate the proposed RPR prototypes. The exactness of the obtained results is estimated using four prototypes operating near 6 GHz, taking into account only the fundamental mode resonant frequency. The theoretical model is compared with the simulations and the measurement results. The second approach of the authors' work which is developed in this paper is focused on the characterization of biological materials in vitro using the RPR prototypes proposed as applicator in the non-destructive control and the medical domain to find the abnormalities of these tissues such as: eczema, psoriasis, cancer, etc. The authors' center of interest will be managed towards the dielectric properties of the biological material to extract the relative permittivity and the loss factor on several samples (liver, fat, chicken, butter, foie gras, etc.).

Dual Band Dual Polarized Slot Cut modified Circular Microstrip Antenna

new broadband and dual band circular slot cut modified circular microstrip antenna is analyzed and proposed. The parametric study to analyze the effects of circular slot which realizes broader bandwidth is presented. The circular slot creates two additional resonant modes near the fundamental TM11 mode resonance frequency of the equivalent circular patch and yields bandwidth of 202 MHz (8%). The polarization of the two modes which realizes broadband response was found to be orthogonal, which leads to the principal plane variations over the bandwidth. Further by using this concept, a circular slot cut dual band and dual polarized circular slot cut circular microstrip antenna in 1000 MHz frequency band is proposed. The proposed antenna yields dual frequency response with orthogonal polarization and variable frequency ratio with bandwidth of 2% at the dual frequencies.

Giant magnetoelectric effect at low frequencies in polymer-based thin film composites

A polymer-based magnetoelectric 2-2 composite was fabricated in a thin film approach by direct spin coating of polyvinylidenefluoride-co-trifluoroethylene onto a Metglas substrate without the usage of an adhesive for the mechanical coupling between the piezoelectric and magnetostrictive materials. For a prototype single-sided clamped cantilever, a magnetoelectric coefficient as high as 850 V cm−1 Oe−1 is observed at its fundamental bending mode resonance frequency at 27.8 Hz and a detection limit of 10 pTHz−1/2 at its second bending mode resonance frequency at 169.5 Hz.

Analysis of shorted-plate compact and broadband microstrip antenna

A broadband configuration of a shorted-plate folded L-slot-cut folded-feed rectangular microstrip antenna was reported, which gave a bandwidth of 2840 MHz (133%). The broader bandwidth was obtained due to the coupling between various modes, which were either a half-wave or a quarter-wave in length. However, a clear description of the modes of the shorted patch that resulted in the broadband response was not given. In this paper, an analysis studying the broadband response of the reported configuration is presented. By studying the voltage and current distributions on the shorted patch, a formulation for its resonance frequency is proposed. The frequencies calculated using the proposed equation closely agreed with the simulated results. Furthermore, the broadband response of the reported configuration was analyzed by studying its resonance-curve plots and surface-current distribution. It was observed that the folded patch and a wing-like extension on the folded-patch portion, the L-slot, and the folded feed modified the various fundamental and higher-order mode resonance frequencies (such as f1/4, 0, f1/4, 1, etc.), as well as the impedances at these frequencies, to yield the broadband response. Furthermore, by optimizing the folded feed length, an increased bandwidth of 3504 MHz (139.2%) was obtained. Over the bandwidth, this configuration showed a radiation pattern with higher cross-polarization levels and with a gain of more than 5 dBi.

이중공진을 사용한 적층기판용 광대역 안테나 설계

In this paper, bandwidth enhanced design of dielectric resonator antenna fabricated in multi-layer substrate is introduced. The proposed dielectric resonator antenna is operating with fundamental TE101 mode and higher-order TM111 mode. Each resonance frequency is dependent on resonator dimensions. As increasing the height of radiating aperture, the higher-order TM111 mode resonance frequency approach the fundamental TE101 mode resonance frequency and the antenna bandwidth increase by double resonance. Three different aperture height size antennas that operated at 7㎓ are fabricated in FR4 multi-layer substrate. Measured 10 ㏈ matching bandwidth is 8 percent for single resonace antenna and 18 percent for double resonance antenna.

Software tools for efficient generation, modelling and optimisation of fractal radiating structures

This study describes in-house developed software tools for designing micro-strip patch fractal antennas. As the fractal geometry is quite complex, IFSMaker application was developed purposely for an easy definition and maintaining of planar fractal structures. In the next step, the authors use the cavity model technique for modal analysis of internal fields of the patch. This simplified model is reasonably fast, so that the optimisation loop may be employed in order to reduce the fundamental mode resonant frequency. This is accomplished with the EvalInFEM, PSOoptimizer and IFSLimiter applications. The theory of characteristic modes is then used to refine the results and finally the antenna is simulated with a full-wave CST simulator, built and measured.

Investigation of the nonlinear dynamics of a partially cracked plate

In this paper the nonlinear vibration of an aircraft panel structure modelled as an isotropic cracked plate and subjected to transverse harmonic excitation is considered for studying the dynamic response, both analytically and experimentally. A crack is arbitrarily located at the centre of the plate, consisting of a continuous line. This mathematical model is in the form of Duffing equation with a cubic nonlinear term. The perturbation method of multiple scales is used to solve the algebraic equation, and then investigated with the results of the direct integration within Mathematica™ and finite element analysis in ABAQUS for the first mode only. In addition, experimental measurements are also carried out to verify the dependence of the cracked plate's fundamental mode shape and resonance frequency on the vibration displacement amplitude. An extermely close agreement between these results is observed.

A piezoelectric microelectromechanical systems ultrasonic radiator.

The development of a piezoelectric micromachined ultrasonic radiator is presented. The transmitter is formed by a radially non‐uniform circular composite diaphragm. The diaphragm consists of a layer of piezoelectric material with annular electrodes. Transduction of the diaphragm occurs when an electric field is induced between annular electrodes across the piezoelectric material creating mechanical strain in the annular region. The strain couples into force and moment resultants that generate diaphragm deflection. A time varying electric field induces vibrations of the diaphragm which in turn generates acoustic waves. Included in the overall systems design of the transmitter is a unique package with back cavity depth control. A systems model incorporates electrical, mechanical, and acoustic components using composite plate mechanics, lumped element modeling, and acoustic theory. Comparison to experimental results is conducted through mechanical and acoustic characterizations. A laser vibrometer system measures diaphragm velocity from which the fundamental mode shape and resonant frequency are extracted. Farfield acoustic measurements are compared to the extrapolation of vibrometer measurements via Rayleigh’s integral. The characterization results show mismatch between devices as well as the equivalent circuit model. Experimental results of the variable back cavity depth show a qualitative match to the systems model.

VHF, UHF and microwave frequency nanomechanical resonators**Some preliminary results to those described herein were presented at the Transducers' 03 conference.

Nanomechanical resonators with fundamental mode resonance frequencies in the very-high frequency (VHF), ultra-high frequency (UHF) and microwave L-band ranges are fabricated from monocystalline silicon carbide (SiC) thin film material, and measured by magnetomotive transduction, combined with a balanced-bridge readout circuit. For resonators made from the same film, we measured the frequency dependence (thus geometry dependence) of the quality factor. We have seen a steady decrease of quality factor as the frequency goes up. This indicates the importance of clamping losses in this regime. To study this source of dissipation, a free-free beam SiC nanomechanical resonator has been co-fabricated on the same chip with a doubly clamped beam resonator operating at similar frequencies. Device testing has been performed to directly compare their characteristics and performance. It is observed that a significant improvement in quality factor is attained from the free-free beam design. In addition, from studies of resonators made from different chips with varying surface roughness, we found a strong correlation between surface roughness of the SiC thin film material and the quality factor of the resonators made from it. Furthermore, we experimentally studied the eddy current damping effect in the context of magnetomotive transduction. A high-aspect ratio SiC nanowire resonator is fabricated and tested for this study. Understanding the dissipation mechanisms, and thus improving the quality factor of these resonators, is important for implementing applications promised by these devices.

Imaging surface-acoustic fields in a longitudinal leaky wave resonator

Acoustic wave fields in a surface-acoustic-wave resonator employing the longitudinal leaky wave mode have been imaged using a scanning Michelson laser interferometer. The synchronous one-port resonator is fabricated on YZ-cut lithium niobate. The vibration amplitude component perpendicular to the surface has been measured at several frequencies around the fundamental-mode resonance frequency of 1.54 GHz and around the Rayleigh-wave resonance frequency of 0.82 GHz. The longitudinal beating pattern, typically observed in the resonators utilizing Rayleigh waves, is not observed in the longitudinal leaky surface acoustic-wave resonator within the measured frequency range.