Frequency Bandwidth Research Articles

An Artificial Intelligence-Based Hybrid Approach to Detect the Type of Buried Objects with Broad Frequency Band Antenna Systems

Knowing the type of buried object before excavation prevents unnecessary excavation. Moreover, it saves time and money. In this study, an experiment set was prepared for the detection of buried objects. The experimental set was composed of an antenna that sends and receives electromagnetic waves in a wide frequency band, software that records and processes reflections, and a sandbox. In the study, metallic and non-metallic objects with different depths, sizes and shapes were buried in this sand pool and measurements were taken along a profile. 2D images were created from the measurements and image processing techniques were applied to these images. Classification algorithms were used to detect the type of bruied object from processed images. To increase the success of the algorithms, correlation-based attribute selection (CFS) and Principal Component Analysis (PCA) were used as attribute selection techniques. Genetic algorithm (GA), Particle Swarm Optimization (PSO), Harmony search (HA), and Evolutionary search (EA), which are among the metaheuristic optimization algorithms, were preferred as search methods in attribute selection with CFS. The performance of the algorithms was analyzed using the 10-fold cross-validation method. As a result, it was understood that the use of the PCA algorithm in attribute selection increases the classification success more than metaheuristic algorithms. The most successful among the classification algorithms used is the Random tree algorithm. After PCA, the accuracy value of this algorithm was 95.8 Therefore, a hybrid approach is proposed in which PCA and Random tree algorithms are used in the software embedded in the measurement system.

A 5 mW 28 nm CMOS Low-Noise Amplifier with Transformer-Based Electrostatic Discharge Protection for 60 GHz Applications

This paper presents a low-power 60 GHz low-noise amplifier (LNA) designed for Gbit/s applications using 28 nm CMOS technology. The LNA exploits a single-stage pseudo-differential architecture with integrated input transformer for both electrostatic discharge (ESD) protection and simultaneous noise/impedance matching. An effective power-constrained design strategy is adopted to pursue the lowest current consumption at the minimum noise figure (NF), with the best tradeoff between gain and frequency bandwidth. The LNA, which has been designed to drive an on–off keying (OOK) demodulator, is operated at a supply voltage as low as 0.9 V and achieves a voltage gain of about 21 dB with a 3 dB bandwidth of 2 GHz around 60 GHz. Thanks to the proper impedance transformation at the 60 GHz input, the amplifier exhibits an NF of 6.3 dB, also including the input transformer loss with a very low power consumption of about 5 mW. The adoption of a single-stage topology also allows an excellent input 1 dB compression point (IP1dB) of −4.7 dBm. The input transformer guarantees up to 2 kV human body model (HBM) ESD protection.

Negative impact of vibration on process pipelines of a compressor station with electrically driven gas pumping units

Relevance. In gas industry, the amount of equipment that has outlived its intended service life is increasing every year. In accordance with the law “On Industrial Safety of Hazardous Production Facilities,” compressor stations are dangerous objects, the reliable operation of which largely determines the condition of main gas pipelines. Technological pipelines of a compressor station are important objects of this system. They are subject to strict requirements due to the action of static and dynamic loads on them. Reliability of compressor stations is based on the results of a study of the condition of the object and the main factors affecting increased wear of equipment. The solution to wear problem is timely monitoring of equipment, in particular level measurement and determining the causes of pipeline vibrations using vibration diagnostics methods, and frequency and modal analysis methods. Aim. To study the causes of increased dynamic loads on the technological piping that arise during the operation of electric and gas pumping units at a compressor station using vibration monitoring methods. Methods. Vibration monitoring methods to analyze the causes of increased vibration values in the process piping of a compressor station with an electric gas pumping unit. Results and conclusions. The authors have measured vibration in a wide frequency band and assessed the technological condition of the main equipment of the compressor station with EGPA-6.3/8200-56/1.44-R based on the regulatory documentation STO Gazprom 2-2.3-324-2009. The main frequencies of the root-mean-square value of the vibration velocity, at which the highest vibration values were observed, were identified, and a modal analysis was performed using ANSYS software. Based on the results of natural studies and modal analysis, it was concluded about the occurrence of resonant high-frequency oscillations, multiple of the rotor rotation frequency.

Cantilever configurations in vibration-based piezoelectric energy harvesting: A comprehensive review on beam shapes and multi-beam formations.

Abstract Vibration-based energy harvesting technology is a well-established research area that has attracted tremendous interest over the last decade. This interest is primarily owing to its extension into a wide range of engineering domains, particularly in Microelectromechanical Systems (MEMS). The cantilever beam is the most common and widely used model for vibration-based energy harvester, driven by two key factors: a) simplicity in design, and b) high output power density. Numerous studies over the years have focused on optimizing the cantilever beam design to increase output power capacity and/or widen the frequency bandwidth of the harvester. While researchers have proposed a plethora of cantilever beam configurations for specific purposes (e.g., low-frequency harvesting, multi-directional frequency harvesting, etc.), there is a notable lack of detailed literature on the types and configurations of cantilever beams. This gap hinders researchers from gaining a comprehensive understanding of the cantilever beams already introduced. Following the need, in this article a comprehensive review is made to list the types of cantilever beams proposed by the researchers over the years. This review covers the working principles of piezoelectric energy harvesting, analyses existing solutions geared towards increasing power output and widening working frequency, and discusses diverse configurations including single and multiple beam setups. The listed beams are categorized based on their structural shape and organization such that it can be helpful for a reader to anticipate which cantilever beam design can be suitable for a specific need. Power output capacity and operating frequency for every beam design are also presented in a tabular form, under each beam category. This would enable the researchers to tailor their designs for specific applications, enhance material efficiency, drive innovation, and open new application possibilities.

Fast acquisition method of battery electrochemical impedance spectra based on impedance fragments

Electrochemical impedance spectroscopy (EIS) is often used for battery characterization and monitoring. However, there are still difficulties in acquiring battery impedance spectra in large quantities and wide frequency bands in practical applications. The lower the frequency range of acquisition, the longer the measurement time spent, and the higher the frequency range of measurement, the more expensive the measurement equipment, and these problems seriously limit the wide application of impedance information. To address this problem, this study proposes a method for fast acquisition of electrochemical impedance spectra of lithium-ion batteries based on impedance fragments. Firstly, impedance segments at specific frequencies in the EIS are selected as features based on the distribution of relaxation times (DRT). Then, a Long Short-Term Memory (LSTM) neural network model is used to reconstruct the complete impedance spectrum, and a population optimization algorithm is used to optimize the hyperparameters in the model. The validation results indicate that the reconstructed RMSE error is only 14.26 mΩ, corresponding to a MAPE of 1.65 %, while the measurement time is reduced to 27.01 % of the original measurement time. Finally, the performance of this method in identifying fractional-order model parameters is further discussed.

Small size dual-band coupled-line coupler for WiMAX applications

Abstract In this paper, a symmetric compact dual-band coupled-line coupler is proposed using microstrip transmission lines, circular resonators, and spiral lines for WiMAX applications. The proposed coupler provides two narrow operating bands, high coupling and isolation, and suitable return loss. The primary design consists of two parallel-coupled lines with a flat coupling over a wide frequency band. Then, the bandwidth, return loss, and isolation are optimized by adding circular resonators and spiral lines to achieve a compact size. In this design, the return loss is better than 30–35 dB in the bandwidth 3.4–5.79 GHz. Finally, this structure is fabricated using a Rogers-RT Duroid 5,880 substrate with a thickness of 20 mil, a loss tangent of 0.0009, a dielectric constant of 2.2, and an area of 18.8 × 14 mm2. The results of the measurements are in good agreement with those of the simulation.

An Inductor‐Less Zero‐IF Down‐Conversion Mixer With Low Flicker Noise and High Conversion Gain

ABSTRACTThis paper presents a novel active inductor (AI) to improve the performance of a down‐conversion active mixer in terms of conversion gain (CG) and flicker noise. The proposed AI exhibits negative resistance and partially flat inductance over a wide frequency band of 0.5–4.5 GHz. The effect of inserting the AI between the source of the switching quad of a Gilbert cell mixer is theoretically analyzed. The proposed inductor‐less mixer, designed to operate at a 2.4‐GHz RF input frequency and a 10‐MHz IF output frequency, employs current reuse and self‐forward body bias (SFBB) techniques. The proposed circuit is simulated in Cadence Spectre‐RF using RF‐TSMC 0.18‐μm CMOS technology. Post‐layout simulations demonstrate that the proposed AI significantly reduces flicker noise by over 23 dB at an IF output frequency of 1 kHz and improves the CG by over 16 dB at an RF frequency of 2.4 GHz. The proposed mixer achieves a CG of 37.6 dB and a flicker noise corner frequency of 6 kHz. Additionally, it exhibits a third‐order intermodulation intercept point (IIP3) of −5.2 dBm and a double‐sideband noise figure (DSB‐NF) of 6.1 dB at the IF output frequency of 10 MHz. Operating with a 1.5‐V supply, the proposed mixer consumes 10.6 mW of power.

Highly Amplified Broadband Ultrasound in Antiresonant Hollow Core Fibers

High‐frequency broadband ultrasound in nested antiresonant hollow core fibers (NANFs) is investigated for the first time. NANFs have remarkable features enabling high‐resolution microscale optoacoustic imaging sensors and neurostimulators. Solid optical fibers have been successfully employed to measure and generate ultrasonic signals, however, they face issues concerning attenuation, limited frequency range, bandwidth, and spatial resolution. Herein, highly efficient ultrasonic propagation in NANFs from 10 to 100 MHz is numerically demonstrated. The induced pressures and sensing responsivity are evaluated in detail, and important parameters for the development of ultrasonic devices are reviewed. High pressures (up to 234 MPa) and sensing responsivities (up to −207 dB) are tuned over 90 MHz range by changing the diameters of two distinct NANF geometries. To the best of knowledge, this is the widest bandwidth reported using similar diameter fibers. The results are a significant advance for fiber‐based ultrasonic sensors and transmitters, contributing to improve their efficiency and microscale spatial resolution for the detection, diagnosis, and treatment of diseases in biomedical applications.

Frequency experimental identification approach for single-phase induction motor common-mode parameters

Introduction. The presence of broad-spectrum and high-amplitude electromagnetic interference (EMI) within a single-phase induction motor (SPIM) drive poses a significant threat to both the system and other electronic equipment. High-frequency (HF) models of electrical motors play a critical role in overcoming these challenges, as they are essential for characterizing electromagnetic compatibility (EMC) in drives and designing effective EMI filters. The novelty of this study proposes an enhanced HF motor model based on transfer functions (TFs) to accurately represent the motor’s behavior at HFs for frequency-domain analyses in the range of 100 Hz to 30 MHz. Purpose. The equivalent HF model for a SPIM is discussed in this paper. The suggested equivalent circuit describes a motor’s common-mode (CM) properties. Methodology. HF model was developed by a frequency-domain analysis utilizing an experimental setup and MATLAB software. The motor impedance analysis is based on the measurement of variations in motor characteristics as a function of frequency in the CM setup. Originality. TF has been tuned using an asymptotic identification method of Bode to match the behavior of the real impedances of the motor parameters as a function of the frequency in the CM configuration. This tuned TFs are then synthesized into a comprehensive wideband EMC equivalent circuit model using the Foster network technique, which can be then simulated in any Spice-based simulator tools. Results. The proposed mathematical model was employed to conduct simulations, and the resulting predictions were validated against experimental data. CM response of the EMC equivalent circuit at low, medium, and HFs were compared between simulations and experimental measurements using Lt-Spice simulator software. Practical value. It is observed that results show satisfactory agreement with the measurements over a large frequency bandwidth [100 Hz–30 MHz], and the equivalent model of SPIM can be cascaded with other electronic and electrical modules to form a complete single-phase electric drive system model for fast analysis and prediction of system level EMI and electromagnetic sensitivity. References 37, table 5, figures 13.

Generation of frequency-shift keying (FSK) and amplitude-shift keying (ASK) RF signals by diode-tuned Fourier domain mode-locked opto-electronic oscillator

An approach to the generation of frequency-shift keying (FSK) and amplitude-shift keying (ASK) RF signals with a diode-tuned Fourier domain mode-locked opto-electronic oscillator (FDML OEO) is proposed and demonstrated. We use a low-cost varactor diode tuned phase shifter to form a high speed tunable bandpass filter (TBF) to implement the FDML-OEO. When a square wave modulation signal is used to drive the TBF, FSK RF signals are generated, with the flexibility to easily change the center frequency and tuning bandwidth of the FSK signals. For the ASK RF signal generation, a band-pass filter (BPF) with a bandwidth less than the TBF tuning range is added to the FDML OEO RF feedback loop. When the TBF center frequency hops in and out of the BPF bandwidth within a mode locking period, the FDML OEO generates ASK RF signals. The phase noises of the FSK and ASK RF signals generated by our FDML-OEO are both measured to be −123dBc/Hz at 10 kHz offset frequency. The key significance of this approach is that no microwave source is required to generate the ASK signal and reconfigurable FSK and signals, which may find wide applications in future radar and communications systems.

Customizable Generation of Arbitrary‐Order Polarization Vortices by Spin‐Decoupled Geometric Phases

AbstractDue to nontrivial field topologies, polarization vortices carrying polarization singularities have attracted increasing interest in the fields of optics and photonics. However, the conventional methods for generation of polarization vortcies still suffer from the complexity and the heavy bulk. In this work, taking advantage of spin‐decoupled geometric phase in metasurfaces, a novel method is proposed to generate polarization vortices with customizable topological charges. By tailoring spin‐decoupled geometric phases generated by the metasurface, distinct helical phase profiles can be imparted to left‐ and right‐handed circularly polarized components. Consequently, two scalar vortices with different topological charges can be simultaneously generated in the two orthogonal circular polarization components, leading to the generation of the polarization vortices with the needed topological charges and the diverse morphologies. Both simulation and experimental results well demonstrate the method. Owing to the nondispersive feature of geometric phases, the designed metasurface works well in a wide frequency band. The proposed method contributes a reliable and feasible solution for customizing the generation of polarization vortices, which can be further transposed to other frequencies and applied to information encoding and polarization detection etc.

Theoretical investigation of Rayleigh-type surface acoustic waves with high electromechanical coupling coefficient in c-axis-tilted ScAlN film/3C-SiC substrate structure

Surface acoustic wave (SAW) resonators are essential components of mobile communication technology. Advanced performance SAW resonators are needed to support beyond fifth-generation mobile communication technology, which aims to achieve unprecedentedly high data rates and low latency using wide frequency bands in the RF spectrum. This study theoretically investigates the propagation characteristics of a non-leaky Rayleigh-type SAW (RSAW) propagating in a c-axis-tilted ScAlN film/3C-SiC substrate structure. By appropriately selecting the c-axis tilt angle and the film thickness of the ScAlN film, a high electromechanical coupling coefficient (K2) value was obtained in the second-mode RSAW (Sezawa wave). The maximum K2 value for the Sezawa wave was 8.03%, with a phase velocity of 7456 m/s and a power flow angle of 0° under the structural conditions where the K2 value was maximized. These properties offer significant advantages for achieving wide frequency bands, high operating frequencies, and ease of design for SAW resonators. The structural conditions under which good propagation characteristics were obtained in the Sezawa waves were found to coincide with the conditions that maximize the electromechanical coupling coefficient of the quasi-longitudinal wave in the ScAlN film, and a significant increase in the shear vertical component of Sezawa wave particle displacement was observed. Additionally, ScAlN films with a 40% Sc concentration can be fabricated using sputtering and molecular beam epitaxy. Recent advancements have reported the production of high-quality 3C-SiC wafers and large 3C-SiC film/silicon wafers. Therefore, the c-axis-tilted ScAlN film/3C-SiC substrate structure shows great potential as a candidate for next-generation SAW resonators.

Design of a compact quad-port wideband printed MIMO antenna for vehicular communication environment

ABSTRACT A wideband quad-port Multiple Input Multiple Output (MIMO) antenna with efficient isolation characteristics for 5 G New Radio (5 G-NR) applications is presented. The proposed antenna works in the span of 3–6 GHz frequency covering the n77/n78/n79 bands also covering the 5 G-V2X band (3300–5000 MHz), LTE-46 band (5150–5925 MHz) and Dedicated Short Range Communication (DSRC) at 5.9 GHz band. The single element of the MIMO antenna structure is modelled by an elliptical structure stacked on a rectangular patch along with the feedline on the conducting plane. The ground plane is modelled as a rhombic design providing a Defected Ground Structure (DGS) to provide the resonance at the desired frequency band. Later, the antenna is evolved as a four-element MIMO system by arranging the antenna elements orthogonal to each other with a distance of separation between the adjacent antenna elements considered to be 10 mm. The all-inclusive dimension of the proposed antenna is 65 × 65 mm2. The simulated MIMO structure is fabricated and measured for antenna parameters and MIMO parameters such as isolation characteristics and MIMO diversity performances. The simulated values are obtained at acceptable limits with the measured values for the proposed wideband frequency range of operation. The compact, wideband antenna is found to be suitable for various 5 G-NR applications, especially Wi-Fi-assisted Vehicular Communication in the sub-6 GHz frequency range.

Experimental verification of sound power determination methods based on radiation matrix

Theoretical foundation of sound power determination from a sound radiating surface using volume velocity and acoustic radiation matrix (ARM) is well established in the literature. However, a detailed experimental investigation of the accuracy of this method over a wide frequency band has not been presented. In this study, the ARM method is analyzed thoroughly to identify factors that can affect the accuracy of the calculated sound power. To do so the acoustic radiation matrix is observed closely as this is the main parameter responsible for the determination of the sound power. Further experiments are performed to calculate the sound power using ARM method and results were compared to the results obtained using the ISO 9614-2. Comparison of these results in wide frequency bands provides insight into the acoustic radiation matrix based on the assumptions made during the modeling of the ARM method. These insights are then used to improve the accuracy of the model with the motivation to imply this method to the insitu measurement of the large building facades.

A high sensitivity and wide frequency band vector hydrophone using PZT-based four spiral beam structure

The utilization of a high sensitivity and wide frequency band vector hydrophone exhibits significant potential in the exploration of underwater target. However, enhancing these performance remains a challenge due to limitations in materials and structures. Herein, we report a micro-electro-mechanical system (MEMS) vector hydrophone (FSPVH) built on lead zirconate titanate (PZT) film with four spiral beam structure and polyamide (PA) microsphere. The optimization of the structural dimensions and PZT thin film distribution has been the result of simulation. The FSPVH have been fabricated using MEMS technology, and the prototype has been assembled. The FSPVH was tested in a standing bucket wave calibration system. The results show that FSPVH achieve a sensitivity of −181.5 dB (0 dB = 1 V/μPa) at 1100 Hz, and the work bandwidth is 20–1330 Hz. Meanwhile, it exhibits a satisfactory “8″ shape directivity. This work provide theory and technique supports of vector hydrophone with high sensitivity and wide frequency band.

Damage detection by means of broadband local wavenumber estimation in plate-like structures

This short communication evinces the ability of the CFAT methodology [Q. Leclère, JSV, 2015] to detect and characterize thickness-loss defects on homogeneous flat panels. A contactless measurement of the velocity field of an aluminium plate is performed by scanning laser vibrometry, from which the equivalent rigidity (apparent bending stiffness) is locally estimated within a wide frequency band in the ultrasonic domain. The method allows imaging thickness-reduction defects on the hidden face of an aluminium plate up to several hundreds of kilohertz. The first part details the experimental protocol, followed by a second enhancing the identification of the wavenumbers of symmetric S_0 and antisymmetric A_0 modes. The comparison with theoretical Lamb waves dispersion curves reveals the precision of the method. Finally, the methodology validates the possibility to precisely estimate the local material thickness and as a consequence the location, size and depth of a reference defect in the shape of a flat bottom hole (assuming homogeneous material properties of the plate).

Experimental and numerical investigation of soundproof panels using acoustic metamaterials with porous material

Acoustic panels are often used in buildings and automobiles. For sound absorption in panels, high sound absorption performance in a wide frequency band can be achieved by combining porous sound absorption, resonant sound absorption, vibration sound absorption, and acoustic metamaterials. This study proposes a highly sound-absorbing panel structure by using an acoustic metamaterial that generates local resonance to a double-walled structure filled with porous material. In the soundproof panel of this study, local resonance is generated by a structure in which slits are made in a porous material. By the through-holes of the slits, local resonance occurs, but sound leakage and thermal viscosity in the slits may affect the sound absorption effect. Therefore, in this study, sound transmission loss for various cases with differing factors such as the use of porous materials, the presence of spiral slits, and layer configurations are compared through the acoustic analysis and experiments. The results substantiate that the proposed panel structure has high soundproofing performance in wide frequency ranges, each driven by distinct physical principles.

Optimisation of underwater acoustic sensor networks

The oceans are the scene of intense economical and industrial activities. It is becoming even more competitive with recent military activities and the upcoming development of marine renewable energies. All of these activities have a significant impact on marine ecosystems and must be carefully evaluated for any maritime planning. The marine environment is also a very effective medium for the propagation of acoustic waves over long distances, depending on the frequency, the source level, the static (bathymetry) and the dynamic (hydrology) oceanographic conditions. Such conditions make acoustic sensors primary candidates for underwater investigations and the distribution of mixed sensors with various sensitivities, frequency bandwidths or positioning can be optimized for detection, localization or monitoring purposes. This contribution aims to present a methodology based on evolutionary algorithms which considers the overall physical state of the marine environment and determines the optimal configurations of mixed underwater acoustic networks. The relevance of various objectives, or metrics, can be discussed, as well as specific search operators for crossover and mutation based on preliminary results.

All-optical infrasound sensor based on a Fabry-Perot interferometer

Recent demands for infrasound measurement, whether for detecting violent atmospheric events or evaluating the environmental impact of wind farms, require new acoustic calibration standards in the frequency range below 2Hz. Expanding the frequency bandwidth of microphones remains a limited strategy since they are designed to filter out continuous components. An alternative method for measuring infrasound is proposed, which relies on a Fabry-Perot interferometer. This technique has been studied extensively for static pressure measurements with success. Therefore, adapting a Fabry-Perot refractometer to perform acoustic measurements is not only a technical challenge but also an opportunity to bridge the gap between static pressures and acoustic metrology. As acoustic movement involves both small pressure and temperature variations, it is important to account for their coupled effects in interferometer measurement results. Since the temperature variation field in the measurement system cannot be characterised experimentally, an analytical model has been developed. The chosen theoretical and technical solutions are validated by the good agreement between experimental results obtained with the refractometer carried out and other calibrated sensors in the frequency range from 40mHz to 1.5Hz. These results also highlight the improvements required to bring the device up to the level of an infrasound reference instrument.

A novel cut-out piezoelectric beam with limiters for broadband energy harvesting

In this paper, we proposed a novel cut-out piezoelectric beam with two pairs of motion limiter for broadband operation. By means of the finite element simulation, a superior geometric structure of the corresponding linear model is designed and the model parameters are determined, then the simulation results are verified by experiments. The subsequent experiments mainly investigate the effect of the position of the limiter on the beam and the size of the limiting gap on the amplitude–frequency response of the system. The experimental results show that the frequency bandwidth of the first resonance peak can be significantly expanded from 2.45Hz to 6.28Hz by selecting suitable limiter parameters, which can increase of 256.33% compared with no limiter. Meanwhile, limiters also cause a maximum 171.79% increase in the primary resonance voltage amplitude, and the level of anti-resonance valley can be increased up to 5.35 times. Finally, the influence of external resistance load on the output power of the system is discussed through detailed parametric study, and the maximum power output of 370μW is achieved.