Compatibility Measurements Research Articles

Microwave and Optical Electric Field Interaction in Microwave Polarization Detector Based on Photonic Technology for EMC Measurement

We analyze the interaction of microwave and optical electric field in a microwave polarization detector based on photonic technology for Electromagnetic Compatibility (EMC) measurement. The detector consists of two orthogonal optical waveguides and patch antennas embedded with two orthogonal gaps fabricated on an Electro-Optic (EO) crystal. Wireless microwave signals can be received, separated and converted directly to lightwave signals through optical modulation using the proposed detector. This detector operates with no external power supply and with low microwave distortion. Microwave polarization can be identified using the proposed interface. In addition, it enables us to measure the magnitude and phase of the wireless signal simultaneously. The analysis of the device was done and presented at the operation frequency of 26 GHz. The proposed interface can be applied for EMC measurement through the radio-over-fiber link.

Compatibility measurement-based group decision making with interval fuzzy preference relations

In this paper, we put forward a ratio-based compatibility degree between any two ]0,1[-valued interval numbers to measure how proximate they approach to each other. A compatibility measurement is presented to evaluate the compatibility degree between a pair of ]0,1[-valued interval fuzzy preference relations (IFPRs). By employing the geometric mean, a measurement formula is proposed to calculate how close one interval fuzzy preference relation is to all the other interval fuzzy preference relations in a group. We devise an induced interval fuzzy ordered weighted geometric (IIFOWG) operator to aggregate ]0,1[-valued interval numbers, and apply the induced interval fuzzy ordered weighted geometric operator to fuse interval fuzzy preference relations into a collective one. Based on the compatibility measurement between two interval fuzzy preference relations, a notion of acceptable consensus of interval fuzzy preference relations is introduced to check the consensus level between an individual interval fuzzy preference relation and a collective interval fuzzy preference relation, and a novel procedure is developed to handle group decision-making problems with interval fuzzy preference relations. A numerical example with respect to the evaluation of e-commerce websites is provided to illustrate the proposed procedure.

Two novel low-firing germanates Li2MGe3O8 (M = Ni, Co) microwave dielectric ceramics with spinel structure

Two low-firing ceramics Li2MGe3O8 (M = Ni, Co) were prepared using the solid state reaction method and their microwave dielectric properties were characterized. X-ray diffraction analysis showed that both ceramics crystallized into a cubic spinel structure. Both ceramics were well densified at temperatures lower than 960°C. Li2NiGe3O8 ceramic sintered at 940°C with relative density of ~95.2% obtained the optimum microwave dielectric properties with a relative permittivity (εr) ~8.6, a quality factor (Q×f) ~42,200GHz (at 12.2GHz), a temperature coefficient of resonance frequency τf ~ −78.2ppm/°C. For Li2CoGe3O8, the ceramic sintered at 950°C had a relative density of 95.4%, a εr of 9.0, a Q×f of 40,500GHz (at 12.6GHz) and a τf of −42ppm/°C. The negative τf values could be tuned by forming composite ceramics with rutile TiO2. Chemical compatibility measurement indicates that both ceramics did not react with silver.

A Low-Cost, Environment-Friendly Lignin-Polyvinyl Alcohol Composite Separator Using a Water-Based Method for Safer and Faster Li-Ion Batteries

A lignin/polyvinyl alcohol (lignin/PVA) composite membrane has been prepared as a separator for lithium-ion batteries (LIBs) using a simple, low-cost, environment-friendly, water-based method. Lignin is a low-cost, naturally occurring, widely abundant, sustainable, biodegradable, and biocompatible material. Polyvinyl alcohol (PVA) has good hydrophilicity, biocompatibility, chemical and thermal stability, mechanical strength, and abrasion resistance. PVA can serve as a host skeleton to draw fibers out of the lignin/PVA composite using a spinning method. In this work, Lignin and polyvinyl alcohol (PVA) were dissolved in water separately, and the water-based solution was mixed together to make the dope – from where the electrospun fibers were drawn to form a non-woven lignin/PVA membrane. A highly porous interpenetrating network structure resulted, which was revealed by scanning electron microscopy. Electrolyte compatibility, uptake tests, and contact angle measurements were examined with three different electrolytes focusing different anodes and supercapacitors, and they all showed favorable results. Thermal shrinkage test and thermogravimetric analysis showed high thermal stability and good flame retardant properties of the membrane. Electrochemical cycling performances were investigated comparing to commercial Celgard separator, using Li/Li(Ni1/3Mn1/3Co1/3)O2 electrodes, and they showed good results for lignin/PVA membrane. Rate performance and electrochemical impedance spectroscopy revealed high rate performance using the lignin/PVA membrane that is caused by its high ionic transport property. The lignin/PVA composite separator showed enhanced physical, thermal and electrochemical properties, and can be considered as a suitable separator for LIBs with graphite or silicon anodes, as well as for supercapacitors.

Design and Experimental Validation of a Mode-Stirred Reverberation Chamber at Millimeter Waves

The purpose of this paper is to analyze the behavior of a mode-stirred reverberation chamber at millimeter waves. An experimental chamber with 0.423m × 0.412m × 0.383m dimensions has been built taking into account mechanical, electromagnetic, and measurement constraints for operation in Ka, U, and V bands. Its design warrants a relatively high quality factor (9 ×104 at 60 GHz), which is confirmed by measurements using frequency stirring. The statistical behavior of the experimental electromagnetic field inside the chamber in the 58.5-61.5-GHz range is consistent with that of a classical reverberation chamber. To the best of our knowledge, this is one of the first reverberation chamber designed and optimized around 60 GHz. It can be used as a test facility for electromagnetic interference and compatibility measurements at millimeter waves as well as for bioelectromagnetic applications.

Optimization and Performance Evaluation of an AC-Chopper Ballast for HPS Lamps

Electronic ballasts for high-pressure sodium lamps based on an ac-chopper topology are proposed as a cheaper and less complex alternative to the industry-standard low-frequency square-wave ballasts. In this paper, the design process of the ac-chopper ballast is reviewed, and the design tradeoffs caused by the single-stage topology are discussed. The analytical and simulation results are verified with measurements of a 250-W prototype system, including a detailed list of the losses for the different circuit components and electromagnetic compatibility measurements. Due to the disadvantages of the single-stage topology, a comparison to a two-stage ballast using the inverter stage of the ac-chopper ballast with a separate power factor correction stage is provided.

Evaluation and Optimization of Ba<sub>0.2</sub>Sr<sub>0.8</sub>Co<sub>0.9</sub>Nb<sub>0.1</sub>O<sub>3-</sub><sub>δ</sub>-Gd<sub>0.1</sub>C<sub>e0.9</sub>O<sub>1.95</sub> Composite Cathodes for IT-SOFCs

Ba0.2Sr0.8Co0.9Nb0.1O3-δ(BSCN0.2)-xGd0.1Ce0.9O1.95(GDC) (x = 10, 20, 30 and 40 wt.%) composite cathodes were investigated for the potential application in the IT-SOFCs. The results of chemical compatibility measurement show that a small number of Gd and/or Ce ions may melt into the lattice of BSCN0.2 to form BSCN0.2-GDC solid solution. Thermal expansion coefficients effectively reduced by the incorporation of GDC. The electrochemical performance of BSCN0.2-xGDC composite cathodes increased with increasing x from 10 to 30 wt.%. When x = 30 wt.%, the area specific resistances were only 0.040 and 0.017 Ω cm2at 750 and 800oC, respectively. This improved electrochemical performance is attributed to the good thermal expansion match between BSCN0.2-xGDC composite cathode and GDC electrolyte, and the increased oxygen vacancy concentration. With further increasing x, the electrochemical performance of the composite cathode decreased. This result may be due to the ambipolar resistance model of porous composite cathode and the poor electrical conductivity of BSCN-40GDC. The maximum power densities of a BSCN0.2-30GDC/La0.9Sr0.1Ga0.8Mg0.2O3-δ/NiO-Sm0.2Ce0.8O1.9single-cell achieve 537 and 722 mW cm-2at 750oC and 800oC, respectively. These results indicate that the BSCN0.2-30GDC composite cathode is a promising candidate for IT-SOFC.

Issue on Calibration of Direct Feed Biconical Antenna in a Semi-Anechoic Chamber Using Standard Antenna Method

Antenna calibration is crucial to ensure the accuracy of Electromagnetic Compatibility (EMC) measurement results. Standard Antenna Method (SAM) is one of the methods widely used in antenna calibration which requires reference antenna with known Antenna Factor (AF) in a free space environment. The work presented in this paper is on the calibration of the AF of a direct-feed biconical antenna in a semi-anechoic chamber (SAC) with considerations given to the effects of ground plane, antenna height, reference antenna type and effects of phase center. The frequency range for the analysis is from 200 MHz to 2 GHz. It is found that antenna located 1.5 m from ground provides the best result compared to modeling. In addition, the phase centers of the reference and test antenna must be at the same positions during the measurements.

Wave Impedance in Reverberation Chambers

This letter concerns probability density functions of the complex impedance of fields in mode-stirred reverberation chambers. They are based on the electric- and magnetic-field statistics derived for ideal reverberation conditions. The implications of these distributions on electromagnetic compatibility measurements using reverberation chambers are also discussed.

Formation of rutile fasciculate zone induced by sunlight irradiation at room temperature and its hemocompatibility

The fasciculate zone of phase pure rutile was fabricated under sunlight irradiation at room temperature, using titanium tetrachloride as a sole precursor. The crystal phase, morphology and microstructure, and optical absorption behavior of the samples were characterized by X-ray Diffraction, High-Resolution Transmission Electron Microscope (HRTEM) and UV–vis Diffuse Reflectance Spectra (DRS), respectively. XRD results show that the crystal phase of the sample is composed of rutile only, and a lattice distortion displays in the crystallite of the sample. HRTEM results show that the morphology of rutile particle is fasciculate zone constituted of nanoparticles with a diameter of 4–7nm, and these particles grow one by one and step by step. The pattern of the selected area electron diffraction of the sample is Kikuchi type, which can be attributed to the predominant orientation growth of rutile nanoparticles along [001] induced by sunlight irradiation. DRS results show that the absorption threshold of the sample is 415nm, corresponding to the band gap energy of 2.99eV, which is lower than the band gap energy of rutile, 3.03eV. Blood compatibility measurement shows that the sample has no remarkable effect on hemolytic and coagulation activity. The percent hemolysis of red blood cells is less than 5% even treated with a big dosage of the fasciculate rutile and under UV irradiation, and there are no obvious changes of plasma recalcification time after the rutile treatment. Thus, the novel structure of rutile fasciculate has low potential toxicity for blood and is hemocompatibility safe.

A 0.7–20-GHz Strip-Fed Bilateral Tapered Slot Antenna With Low Cross Polarization

This letter presents a bilateral tapered slot antenna (BTSA) as a measurement antenna for electromagnetic compatibility (EMC) and antenna measurements. By virtue of the proposed wideband 50-Ω feeding transition and carefully adjusted tapered slot profile, together with the truncation compensation method, the proposed BTSA maintains a single main beam in the radiation pattern across the entire operating frequency band from 700 MHz to 20 GHz rather than main-beam split above 12 GHz, which is suffered by most traditional horn antennas and tapered slot antennas. Also, better than 25 dB cross-polarization level and less than 2:1 VSWR are obtained within the frequency band of interest. The validity of the proposed design is verified experimentally. The proposed BTSA can be applied to EMC and antenna measurement systems or further employed to construct a dual-polarized BTSA for other measurement applications.

Human-like Manipulation Planning for Articulated Manipulator

A new method based on human-likeness assessment and optimization concept to solve the problem of human-like manipulation planning for articulated robot is proposed in this paper. This method intrinsically formulates the problem as a constrained optimization problem in robot configuration space. The robot configuration space is divided into different subregions by human likeness assessment. A widely used strategy, Rapid Upper Limb Assessment (RULA) in applied ergonomics, is adopted here to evaluate the human likeness of robot configuration. A task compatibility measurement of the robot velocity transmission ratio along a specified direction is used as the target function for the optimization problem. Simple illustrative examples of this method applied to a two Degree of Freedom (DOF) planar robot that resembles the upper limb of a human are presented. Further applications to a humanoid industrial robot SDA10D are also presented. The reasonable planning results for these applications assert the effectiveness of our method.

Time Reversal Efficiency Measurement in Reverberation Chamber

The time reversal (TR) technique is applied in a reverberation chamber (RC) to perform an analysis of antenna efficiency. RC are mainly used for electromagnetic compatibility measurements. They provide through a stirring process the total radiated power from any electromagnetic source placed inside these overmoded cavities with a reasonable statistical uncertainty. Performances of TR techniques also increase with the number of modes or path densities, inherently high in RCs. In this paper, we show how a RC may be used in combination with the TR technique to measure ultra wide band (UWB) antenna efficiency with simple operation all over the frequency band. Principles of this new method called time reversal efficiency measurement (TREM) are provided together with experimental validations. Results are discussed and compared with simulations or other measurement methods.

Resolution adapted finite element modeling of radio frequency interactions on conductive resonant structures in MRI

Prediction of interactions between the radiofrequency electromagnetic field in magnetic resonance scanners and electrically conductive material surrounded by tissue plays an increasing role for magnetic resonance safety. Testing of conductive implants or instruments is usually performed by standardized experimental setups and temperature measurements at distinct geometrical points, which cannot always reflect worst-case situations. A finite element method based on Matlab (The Mathworks, Natick, MA) and the finite element method program Comsol Multiphysics (Stockholm, Sweden) with a spatially highly variable mesh size solving Maxwell's full-wave equations was applied for a comprehensive simulation of the complete geometrical arrangement of typical birdcage radiofrequency coils loaded with small conductive structures in a homogenous medium. Conductive implants like rods of variable length and closed and open ring structures, partly exhibiting electromagnetic resonance behavior, were modeled and evaluated regarding the distribution of the B(1)- and E-field, induced currents and specific absorption rates. Numerical simulations corresponded well with experiments using a spin-echo sequence for visualization of marked B(1)-field inhomogeneities. Even resonance effects in conductive rods and open rings with suitable geometry were depicted accurately. The proposed method has high potential for complementation or even replacement of common experimental magnetic resonance compatibility measurements.

Position Search Technique for Unknown Wave Sources Using Spherical Wave Function

Estimation of wave source position is important technique for searching unknown noise source in electromagnetic compatibility measurement. In this article, a new position search technique for unknown wave sources is proposed by using the spherical vector wave function and point-matching method. In this technique, a few virtual boundaries are placed on surrounding areas, which includes the unknown wave sources. In order to verify the validity of the method, a new demonstrative measurement system is developed and used for experiments in the microwave band. As a result, the position of unknown wave sources can be estimated accurately by using the proposed method.

Chemical compatibility, thermal expansion matches and electrochemical performance of SrCo 0.8Fe 0.2O 3− δ–La 0.45Ce 0.55O 2− δ composite cathodes for intermediate-temperature solid oxide fuel cells

The chemical compatibility, thermal expansion and electrochemical property measurements of the SrCo 0.8Fe 0.2O 3− δ (SCF)–La 0.45Ce 0.55O 2− δ (LDC) composite cathodes for solid oxide fuel cells (SOFCs) were investigated by X-ray diffraction (XRD), thermal expansion coefficients (TECs) and cathodic polarization measurements together with electrochemical impedance spectroscopy (EIS). The results indicated that LDC had good chemical compatibility with SCF and La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ (LSGM), and the addition of LDC to SCF markedly reduced the polarization resistance. When the content of LDC reached 50 wt%, the SCF50 cathode showed the best electrochemical performance, with a cathodic overpotential of 0.1 V at the current density of 1102.0 mA cm −2, together with a polarization resistance of 0.149 Ω cm 2 at 800 °C. The improved electrochemical performance was attributed to the expansion of the electrochemical reaction region into the electrode, and offering an easier path for the oxygen ion transport. Furthermore, the SCF–LDC composite cathodes match better with the LSGM electrolyte.

Synthesis, characterization and evaluation of reflectivity of nanosized CaTiO3/epoxy resin composites in microwave bands

Microwave absorbing materials play a major role in electromagnetic interference and compatibility measurements in anechoic chambers. Nanocrystalline calcium titanate (CT) was synthesized by hydrothermal method and further composites of CT/epoxy resin were fabricated as thin solid slabs of four different weight ratios. The composite material was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which reveals that CT was observed to be in the monoclinic phase with an average crystallite size of 24 nm. The reflectivity measurement of the composite materials was carried out by the transmission/reflection method using a vector network analyzer R&S: ZVA40, in the X- and Ku-bands. The effective permittivity and permeability of the samples was also computed with the help of measured transmission and reflection coefficients. The results show that CT with equal weight of epoxy resin provides −30 dB at 8.5 GHz in the X-band and −19.5 dB at 18.0 GHz in the Ku-band. Reflectivity was found to be better than −10 dB for 2.2 GHz and 1.9 GHz for X-band and Ku-band, respectively and encourages use of it as potential microwave absorber material.

Integrated optics magnetic sensor from 2 kHz to 9 GHz

A new type of integrated optical magnetic field sensor is presented in this paper. The proposed sensor consists of a Mach-Zehnder waveguide interferometer and a doubly loaded loop antenna. Such a structure can successfully avoid detection of the undesired electric field signal. The size of the sensor is 35 mm×6 mm×1 mm. The measurements show that the frequency response is from 2 kHz to 9 GHz, the dynamic range is 98 dB, and the minimum detectable magnetic field is 51.8 μA/m at 1 GHz. Therefore, this sensing system can be used in electromagnetic compatibility measurements.

Postprocessing of Near-Field Measurement Based on Neural Networks

This paper presents postprocessing based on neural network (NN) models to reconstruct the magnetic near-field profile with an improved spatial resolution for one or different frequencies. The models aim at decreasing the time required to perform near-field electromagnetic compatibility (EMC) measurements. The multilayer perceptron (MLP) NNs are used to determine the magnetic near field radiated by passive devices and power electronics components. An optimization method, called the split-sample method, is implemented to determine the structures of the NN. The results obtained with the proposed method are compared with the measurement results. A graphic interface (GUI) is created to simplify the utilization of the developed NN models.

The accurate calibration of EMC antennas in compact chambers — Measurements and uncertainty evaluations

The accurate knowledge of the antenna factor is a fundamental requirement for reliable electromagnetic compatibility (EMC) measurements in emissions, immunity and human exposure tests. According to international standards, the calibration of EMC antennas requires close-to-ideal test sites (or calibration test sites), characterized by very large sizes of the ground plane and of the empty space volume above it (free-space behaviour). On the other hand a great number of EMC test sites are available and designed for measurements at 3 m distance, therefore it would be very convenient to calibrate antennas in such facilities at the cost of an acceptable loss of accuracy. In this paper, the authors investigate the suitability of compact semi-anechoic chambers (standard chambers, compliant for measurements at 3 m distance from the equipment under test) for reliable antenna factor calibrations. As an application, the calibration of a common broadband biconical antenna in the 200–1000 MHz frequency range is here considered and analysed. A detailed experimental analysis is offered for estimating all the relevant uncertainty contributions.