Electromagnetic Field Simulation Research Articles

Substrate Integrated Waveguide Based High Gain Planar Antipodal Linear Tapered Slot Antenna with Dielectric Loading for 60 GHz Communications

The 60 GHz band has the potential to provide high speed wireless communication. Substrate integrated waveguide (SIW) fed millimeter wave high gain antipodal linear tapered slot antenna (ALTSA) is presented in this paper. To obtain high gain the dielectric loading in addition to the corrugation structure is applied to the ALTSA. The use of SIW technology allows a highly efficient, compact and low cost planar design. The antenna is designed and simulated in an electromagnetic field simulation tool. A single element ALTSA is designed first. Then SIW power divider is used for designing 1 × 4 ALTSA array. To validate the proposed design, prototypes have been fabricated and measured. The simulated results agree well with the measured values which validates the proposed design. The measured return loss of single-element ALTSA and 1 × 4 ALTSA array is better than 12 dB over the entire 60 GHz band (57–64 GHz). The measured gain for single-element ALTSA and 1 × 4 ALTSA array is 18.7 ± 0.4 dBi and 22.9 ± 0.6 dBi respectively over the 60 GHz band.

Topology Optimization of Rotor Pole in Switched Reluctance Motor for Minimum Torque Ripple

Torque ripple is a major problem for switched reluctance motors, which may cause undesirable vibration and acoustic noise, especially at low speed. This paper presents an optimal topology structure of rotor for 8/6 pole switched reluctance motor by using the level set method. The nonlinear ferromagnetic material boundary of rotor pole is implicitly represented through an embedded level set function. This method is applied to obtaining the optimal distributions of material in the design domain for minimizing torque ripple and maximizing average torque. In the optimization objective function, the reluctivity of ferromagnetic material is selected as the design variable. The normal velocity is derived from sensitivity analysis, where the adjoint variable method is utilized. Two-dimensional finite element method is employed to calculate the electromagnetic parameters of this electric machine. Analysis results obtained from the transient simulation of electromagnetic field coupled with control circuit show that the torque ripple is reduced effectively by using the optimized rotor structure.

Optimization of the High-Temperature Induction Treatment Modes for Nonlinear Electroconductive Bodies

This paper proposes an approach to the computer simulation of electromagnetic, thermal and mechanical fields in ferromagnetic bodies based on the developed mathematical model for the description of thermo-mechanical processes in electroconductive bodies having different magnetizability and polarizability under electric field conditions. The results of the investigation on the modes of high-temperature induction treatment of bodies made of different ferromagnetic materials are presented. It is shown that by selecting the electric current frequency at the stage of heating and the subsequent cooling conditions, it is possible either to generate residual stresses in bodies, that are close to the given ones, or to reduce the duration of the heat treatment of workpieces under stress constraints.

Kassiopeia: a modern, extensible C++ particle tracking package

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease-of-use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur in flight such as bulk scattering and decay, and stochastic surface processes occurring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle’s state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia.

Complex permeability extraction of FeCo nanoparticles using annular ring resonator and its RF applications

Reconfigurable and tunable antennas/filters are of interest in various radio frequency (RF) applications. This paper addresses use of FeCo soft magnetic nanoparticles for magnetically tuned and reconfigured resonators, filters, and antennas. The RF component designs considered are based on annular ring resonator structures with a composite substrate of 30nm cubic magnetic Fe60Co40 nanoparticles deposited on an FR4 substrate. Accurate permeability extraction of Fe60Co40 is performed for a ring resonator at 3.0GHz with and without external magnetic field biases. Complex permeability extraction procedure is based on best fitting of simulated scattering parameters using finite element method (FEM) electromagnetic field simulator to the measurement results of the composite substrate. The extracted results of soft magnetic permeability are used along with an external magnetic field to develop tunable filter and antenna components for wireless applications.

S-Parameter Deembedding Algorithm and Its Application to Substrate Integrated Waveguide Lumped Circuit Model Extraction

In this paper, a unified method is introduced and formulated for deriving the equivalent circuit model of a guided wave structure as well as its characteristic impedance for any mode. This method is developed through the combination of a generalized multimode calibration and a full-wave simulation, and it is applicable to the fundamental mode as well as higher order modes. The method is verified for both TEM and non-TEM propagating modes and is applied to extract the characteristic impedance and circuit model of non-TEM guided-wave structures. This scheme allows for the effective use of a commercial electromagnetic field simulator in removing inherent numerical simulation noises or errors. Extracting circuit parameters through this technique for establishing equivalent circuit models can overcome the shortcomings encountered in the modeling of guided-wave eigenvalue problems as well as in the design of multimode structures.

Radio-frequency coils for ultra-high field magnetic resonance

Radiofrequency (RF) coils are key components of magnetic resonance imaging (MRI) systems. The primary purpose of this review is to provide a basic theory of RF coil designs and their characterization by bench measurements, electromagnetic field simulations and MR measurements. With the continuing increase of magnetic field strength in MRI instruments, the RF wavelength in the subject under study becomes comparable to or smaller in size than the anatomical dimensions of the tissue under study, which amplifies the signal inhomogeneity. Also, RF energy increases quadratically with the Larmor frequency, which leads to increased heat deposition in the subject, especially at ultra-high field. Elegant RF coil designs are explored here to address these challenges.

SIW Based Antipodal Linear Tapered Slot Antenna for Inter-Satellite Communication Links at 60 GHz

Future space exploration demands inter-satellite links (ISL) that allow high speed communication between two or more satellites. This paper is concerned with the antenna system capable of establishing and maintaining ISL at 60 GHz. A high gain corrugated and hat shaped dielectric loaded antipodal linear tapered slot antenna (ALTSA) based on substrate integrated waveguide technology for inter-satellite communications at 60 GHz is proposed in this paper. A gain of 16.2 dBi achieved with a single element corrugated ALTSA and the 1 × 2 corrugated ALTSA array has a gain of 18.5 dBi with return loss below −10 dB at 60 GHz band. Similarly, the hat shaped dielectric loaded ALTSA has gain of 17.29 dB with single element and 19.22 dB was achieved with two elements ALTSA. Both have good radiation efficiency of above 92%. Electromagnetic field simulation tools have been utilized for the design and simulation of the proposed antennas.

Designing and modeling a linear electric motor for vibration-technology machines

One industrial application of linear motors is as working-body drives of vibration-technology machines. Such drives allow manufacturing of equipment with very low energy consumption and material costs. This paper presents the results of research on substantiation of the prospects of application of linear electric motors as drive vibration-technology machines. The results of designing a linear dc motor are presented. This paper describes the design of the electric motor and its operation in the hold-down and vibrating modes. The main technical characteristics of the motor are given. Simulation of the electric-motor electromagnetic field based on symmetrical setting of the task for the Poisson equation was performed with a view to specifying and verifying the preliminary calculation data. The results of the calculations and simulations show that it is possible to create low-cost, manufacturable, and reliable electrical motors for a linear vibratory actuator.

Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.

Design of bull’s eye structures on gate-defined lateral quantum dots

Quantum repeaters are required for realizing long-distance quantum communication. The quantum repeater consists of a quantum memory to store quantum information and an interface between photonic flying qubits and the memory qubits. Electron spins in gate-defined quantum dots (QDs), which have a relatively long coherence time and high electrical tunability, are promising candidates for such memory qubits because the fundamental technologies of detecting and manipulating single photoelectron spins have been established. The remaining challenge for the realization of quantum repeaters is an efficient coupling between photons and electron spins in the QDs. In this study, we discuss the enhancement of the transmission and the maintenance of the incident light polarization through bull’s eye structures on gate-defined QDs on the basis of electromagnetic field simulations.

Parallel transmission RF pulse design with strict temperature constraints.

RF safety in parallel transmission (pTx) is generally ensured by imposing specific absorption rate (SAR) limits during pTx RF pulse design. There is increasing interest in using temperature to ensure safety in MRI. In this work, we present a local temperature correlation matrix formalism and apply it to impose strict constraints on maximum absolute temperature in pTx RF pulse design for head and hip regions. Electromagnetic field simulations were performed on the head and hip of virtual body models. Temperature correlation matrices were calculated for four different exposure durations ranging between 6 and 24min using simulated fields and body-specific constants. Parallel transmission RF pulses were designed using either SAR or temperature constraints, and compared with each other and unconstrained RF pulse design in terms of excitation fidelity and safety. The use of temperature correlation matrices resulted in better excitation fidelity compared with the use of SAR in parallel transmission RF pulse design (for the 6min exposure period, 8.8% versus 21.0% for the head and 28.0% versus 32.2% for the hip region). As RF exposure duration increases (from 6min to 24min), the benefit of using temperature correlation matrices on RF pulse design diminishes. However, the safety of the subject is always guaranteed (the maximum temperature was equal to 39°C). This trend was observed in both head and hip regions, where the perfusion rates are very different.

磁界を用いたワイヤレス電力伝送における結合係数とコイルサイズのスケール則

Wireless Power Transfer (WPT), such as magnetic resonant coupling using a magnetic field is being studied and discussed for a wide variety of applications. When the transmission distances are large, very large transmitters and receivers need to be considered. However, in the early stages of an investigation, it might be prohibitive to manufacture and evaluate coils of such a large size. To reduce costs and effort, a scaling law can be used to estimate the WPT efficiency of very large coils using the results of smaller coils. In this paper, a scaling law is proposed that relates the coil size to the coupling coefficient, assuming the ratio between the coil diameter and coil length remains constant. The coupling coefficient is one of the parameters that determine the maximum efficiency of magnetic field WPT. The proposed method was verified by an electromagnetic field simulator and experiment. The results of this study provide an easy method for estimating the WPT efficiency of very large coils.

Simulation of electromagnetic fields scattered from arbitrary shaped electric conductors

Simulation of electromagnetic fields scattered from arbitrary shaped electric conductors

Optimized implementation of iterative methods with mixed-precision calculation for electromagnetic field simulation

Optimized implementation of iterative methods with mixed-precision calculation for electromagnetic field simulation

Measurement and Simulation of Induced Voltage and Current on 110 KV Crossing Transmission Lines under UHV AC Transmission Lines

The induced electricity of 110 kV transmission lines which cross the UHV AC transmission lines may threaten personal safety of the maintenance staff. In this paper, field measurement of the induced voltage and induced current on a 110 kV crossing line inside Jinhua in Zhejiang province is performed. The electrostatic induced voltage on the measured line is 12.24 kV. The power frequency electromagnetic field simulation model is established, and the calculation results are consistent with the measured. Influence factors analysis shows that the electrostatic induced voltage on the 110 kV line is 12.78 kV, the electromagnetic induced voltage is 12.3 V, the induced current through ground wire is less than 1A when the UHV lines operate at full load. The induced voltage and current decrease while the crossing distance increases. Parallel lines induction is much higher than crossing lines. The electromagnetic induced voltage after ground knife-switch shut down would exceed the human safety voltage 36 V while the crossing angle is less than 30?, so the temporary ground wire must be hanged to ensure safety of the maintenance staff.

大气电场数据误差的影响分析

为研究大气电场数据误差影响，解决大气电场仪数据一致性问题，本文采用Ansoft Maxwell电磁场仿真软件，以不同尺寸的立方体代替地面上凸出的建筑物、高压线、金属杆、树木等，进行了仿真计算和分析。分析表明：地物环境和电场仪安装高度对地面大气电场测量结果的影响较大，使得地面大气电场仪各观测点数据间缺乏可比性。得出电场仪的安装要考虑环境因素，其离障碍物距离不得低于障碍物高度的3倍、宽度的2倍，同时考虑障碍物高度c和宽深比a/b的影响。设备高度和环境的影响，可利用线性拟合对照标准场所测量数据进行修正。 For the study of atmospheric electric field data error, solving the problem of atmospheric electric field instrument data consistency, this paper simulated different size of the cube instead of the real buildings, high voltage wire, metal rods, trees and so on with Ansoft Maxwell electromagnetic field simulation software. Analysis shows that the terrain environment and instrument installation height on the ground have a great influence on the ground atmospheric electric field measurement results, which makes the atmospheric electric field instrument data lack of comparability between each observation point. It is concluded that the installation of the electric field instrument must consider environmental factors, it away from the obstacle distance shall not be less than 3 times of the barrier height and 2 times of the width, considering the influence of the barrier height c and width depth ratio a/b at the same time. The influence of the height and environmental equipment can use linear fitting to correct with reference to the standard measurement data.

Local measure of the electromagnetic field in magnetic resonance coils: How do simulations help to disentangle the contributions of the electric and magnetic fields?

The development of probes for Nuclear Magnetic Resonance (NMR) spectroscopy of metabolites, biomolecules or materials requires the accurate determination of the radio-frequency (RF) magnetic field strength, B1, at the position of the sample since this RF-field strength is related to the signal sensitivity and the excitation bandwidth. The Ball Shift (BS) technique is a commonly employed test bench method to measure the B1 value. Nevertheless, the influence of the RF electric field, E1, on BS is often overlooked. Herein, we derive, from Maxwell equations, an analytical expression of the BS, which shows the contribution of both the electric and magnetic energies to the BS value. This equation shows that the BS allows quantifying the B1 field strength only in regions where the electric energy is small with respect to the magnetic one. The numerical simulations of electromagnetic (EM) field and energy prove that this condition is fulfilled at 100.5MHz inside the electrically balanced coil of a double-resonance 1H/X 4mm Magic Angle Spinning (MAS) probe since for that circuit, the center of the coil is an antinode for the B1 standing wave and a node for the E1 one. We also show that the simulated BS values agree well with the experimental ones. Conversely, NMR experiments show that the contribution of the electric energy to BS becomes significant when the X channel of this probe is connected to a frequency splitter. In that case, the use of BS method to estimate the B1 value is compromised.

Statistical Variation in Post-Simulated Electromagnetic Fields

This paper presents an algorithm for estimating the variance in simulated electromagnetic fields arising from uncertainties in electrical parameters in a model. The proposed algorithm is shown to be faster and more accurate than the stochastic finite difference time domain method. The main advantage of the algorithm lies in how does not slow down the main simulation of electromagnetic fields, since it is only performed on demand after the main simulation is completed.

A Figure-of-Merit for Design and Optimization of Inductive Power Transmission Links for Millimeter-Sized Biomedical Implants.

Power transmission efficiency (PTE) has been the key parameter for wireless power transmission (WPT) to biomedical implants with millimeter (mm) dimensions. It has been suggested that for mm-sized implants increasing the power carrier frequency (fp) of the WPT link to hundreds of MHz improves PTE. However, increasing fp significantly reduces the maximum allowable power that can be transmitted under the specific absorption rate (SAR) constraints. This paper presents a new figure-of-merit (FoM) and a design methodology for optimal WPT to mm-sized implants via inductive coupling by striking a balance between PTE and maximum delivered power under SAR constraints (PL,SAR). First, the optimal mm-sized receiver (Rx) coil geometry is identified for a wide range of fp to maximize the Rx coil quality factor (Q). Secondly, the optimal transmitter (Tx) coil geometry and fp are found to maximize the proposed FoM under a low-loss Rx matched-load condition. Finally, proper Tx coil and tissue spacing is identified based on FoM at the optimal fp. We demonstrate that fp in order of tens of MHz still offer higher PL,SAR and FoM, which is key in applications that demand high power such as optogenetics. An inductive link to power a 1 mm 3 implant was designed based on our FoM and verified through full-wave electromagnetic field simulations and measurements using de-embedding method. In our measurements, an Rx coil with 1 mm diameter, located 10 mm inside the tissue, achieved PTE and PL,SAR of 1.4% and 2.2 mW at fp of 20 MHz, respectively.