Electromagnetic Coupling Effects Research Articles

Design of film supported single mesa Schottky diodes for above 1THz application with submicron T-junction

A high-performance terahertz Schottky barrier diode (SBD) with a film-supported single mesa structure featuring a low structural parasitic with extremely low dielectric loss is reported in this brief. The fabricated substrate-free SBD is supported with a 2–3 µm polymer film using a low parasitic coupling capacitor of about 0.12 fF. It significantly reduces the electromagnetic coupling effect between the anode and cathode pads by 90% compared with the traditional structure of the same size. To reduce the Schottky junction capacitance at the anode, a submicron T-junction process is used with a low junction capacitance of 0.15 fF. The cutoff frequency calculated by the total capacitance of the diode is up to 4 THz. The substrate-free terahertz monolithic integration circuit based on this film-supported single mesa SBD has better performance in reducing the circuit dielectric loss, exhibiting a remarkable potential for high-frequency applications.

Electromagnetic energy harvesters based on natural leaves for constructing self-powered systems

Pure natural material-based energy harvesters are promising to become green energy sources for constructing self-powered systems, as these devices can produce renewable clean energy by collecting the low-quality mechanical energy or electromagnetic energy from the ambient environment without causing pollution problems. In this work, a natural leaf-made electromagnetic energy harvester (NLMEEH) for harvesting the ambient electromagnetic energy is proposed mainly with environmentally degradable natural fresh leaves. With basic working mechanism of electromagnetic coupling effect, the NLMEEH can produce peak output power density up to ∼4.52 mW/m2, and the energy generating process will continue stably until the natural leaves wither. As typical applications, the energy harvested by the NLMEEHs can be stored or is utilized to power a digital clock and a temperature–humidity sensor, indicating the potential applications in green energy harvesting for distributed sensors in Internet of Things (IoT).

Experimental Study on the Coupling Mechanism of Sensors under a Strong Electromagnetic Pulse.

This paper presents a study on the electromagnetic effects of a main fuel control system under the action of a strong electromagnetic pulse. It assesses the electromagnetic sensitivity of a speed sensor and a linear variable differential transformer (LVDT) sensor. This assessment focuses on the control system’s electromagnetic effects and the sensors’ coupling signals. The effects and signals were determined using radiation and pulse current injection tests. Analysis of the signal at the system power port shows that it is the same as those for the two test methods. Based on analysis of the working mechanism and terminal signals of the sensors, the electromagnetic sensitivity of the system is different under the different electromagnetic pulse conditions. The electromagnetic sensitivity characteristics of the sensors were verified, and the electromagnetic effects of the main fuel regulation control system were analyzed. Meanwhile, the degree of sensor coupling mechanism caused by the electromagnetic coupling effects of the main fuel regulation control system under strong electromagnetic pulses were studied. These findings have clear practical implications for electromagnetic pulse protection of aero-engine control systems.

High-efficient built-in wave energy harvesting technology: From laboratory to open ocean test

The ocean contains a huge amount of renewable energy. There is a tremendous need to develop new ocean energy harvesting technology for long-term and self-sustained global ocean observation. Herein, an omnidirectional and high-efficient built-in wave energy harvesting (WEH) system fully integrated in ocean observing platform is introduced, realizing energy harvesting and self-powered ocean-wave sensing, simultaneously. Based on the chaotic pendulum design and high-efficient electromagnetic coupling effect, the high output power of 520 mW and power density of 0.66 mW/cm3 have been achieved under ultra-low-frequency wave excitation with wave height of 20 cm and period of 1 s, which is extremely higher than most of the reported ones. More significantly, the built-in WEH system was fully integrated with the buoy and successfully completed the offshore test in the Yellow Sea for one month and open ocean test in the Kuroshio Extension (KE) region of Northwestern Pacific for four months. During the offshore test, the working time of an autonomous positioning sensor of the buoy was significant extended from 10 to 25 days, which is 2.5 times longer. During the open ocean test, the built-in WEH system was able to long-term survive in the Kuroshio Extension, which is one of the most dynamically-complex regions in the global ocean. The maximum and averaged output power of 210 and 24.5 mW, respectively, have been achieved, under the ocean wave heights and periods varying from 0.4 to 2.2 m and from 4.2 to 7.2 s. Meanwhile, the generated voltage data can be transmitted via Iridium Satellite and utilized for evaluating and sensing the real-time wave conditions, i.e., wave height and period. It comes to an encouraging conclusion that the built-in WEH system cannot only harvest sufficient energy to extend the service life of ocean observing platform, but also as a self-powered wave sensor to assist ocean monitoring. This work shows a promising milestone in WEH technology from laboratory prototype to practical open ocean application.

The novel sandwich composite structure: a new detection strategy for the ultra-sensitive detection of cyclotrimethylenetrinitramine (RDX)

This study presents a novel sandwich composite structure that was designed for the ultra-sensitive detection of cyclotrimethylenetrinitramine (RDX). Au nanorod arrays (Au NRAs) were prepared and bound to 10−7 M 6-MNA as adsorption sites for RDX, while Au nanorods (Au NRs) were modified using 10−5 M 6-MNA as SERS probes. During detection, RDX molecules connect the SERS probe to the surface of the Au NRAs, forming a novel type of Au NRAs-RDX-Au NRs ‘sandwich’ composite structure. The electromagnetic coupling effect between Au NRs and Au NRAs is enhanced due to the molecular level of the connection spacing, resulting in new ‘hot spots’. Meanwhile, Au NRAs and Au NRs have an auto-enhancement effect on 6-MNA. In addition, the presence of charge transfer in the formed 6-MNA-RDX complex induced chemical enhancement. The limits of detection of RDX evaluated by Raman spectroscopy using 6-MNA were as low as 10−12 mg ml−1 (4.5 × 10−15 M) with good linear correlation between 10−12 and 10−8 mg ml−1 (correlation coefficient R 2 = 0.9985). This novel sandwich composite structure accurately detected RDX contamination in drinking water and on plant surfaces in an environment with detection limits as low as 10−12 mg ml−1 and 10−8 mg ml−1.

Intermediate-state imaging of electrical switching and quantum coupling of molybdenum disulfide monolayer

SignificanceThin transparent semiconductors of two-dimensional materials are attractive for the practical applications in next-generation nanoelectronic and optoelectronic devices. Probing the electron states and electrical switching mechanisms of a molybdenum disulphide monolayer with atomic-scale thickness (6.5 Å) allows us to unlock the full technological potential of this nanomaterial. We introduced a plasmonic phase imaging method to uncover the underlying mechanism and detailed switching dynamics of an electrical-state switching event. This dramatic phase change can be attributed to the reversible switching of classical electromagnetic coupling and quantum coupling effects interplaying between a single metal nanoparticle and molybdenum disulphide monolayer, and the transient intermediate states during the switching event can be directly imaged by a plasmonic technique.

Eigenmode-BLT-Based Method for Calculating the Coupling to Microstrip Antenna Inside a Cavity

The electromagnetic (EM) coupling effects of microstrip antennas have become increasingly prominent in complicated electric systems. In this article, a hybrid method is proposed based on the combination of cavity eigenmode theory and BLT equation. First, the internal electric field generated by the transmission lines inside the resonant cavity is obtained via cavity eigenmode theory. Then, the coupling mechanism between the electric field and microstrip antenna is established through radiation coupling interference. On this basis, the BLT equation and numerical integration method are applied to determine the induced voltage at the target microstrip antenna. Eventually, the proposed approach is validated by a full-wave simulation method and the impact of the microstrip antenna parameters on the coupling interference is discussed. This article provides an analytical method for calculating the coupling of a microstrip antenna. Compared with numerical simulation, this method has certain potential advantages in solving closed electrically large objects. Furthermore, duplicate modeling can be avoided in the same type of scenario.

Investigation on the Influence of Balun to the Lightning Electromagnetic Coupling Effects of Planar Dipole Working at 890–954 MHz

In this article, the influence of balun on the lighting electromagnetic coupling effects of planar dipole working at 890–954 MHz is investigated. The planar dipole is placed near the lightning channel. Based on the electromagnetic model of the lightning return stroke, the following two aspects are researched: first, the influence of the position of balun-cable to the lightning coupling effects, including the influence of the first return stroke and subsequent return stroke to the coupling effects of the planar dipole. Second, the influence of the distance between balun and coaxial cable to coupling effects of antenna. It can be found that the position of the balun-cable has great impacts on the lightning coupling effects of the planar dipole, even exceeding the impacts caused by the polarization of the antenna, which is installed on the communication tower and located near the lightning channel. Meanwhile, although the energy of the first return stroke is much greater than that of the subsequent return stroke, the energy of the subsequent return stroke coupling into the planar dipole is greater than that of the first return stroke. It is also found that the coupling effect of the antenna is approximately proportional to the distance between the balun and the coaxial cable at the same height above the ground.

Determination of the Forward Electromagnetic Coupling Radius in Chaff Cloud

Chaff cloud is a passive jammer that is widely used in many tactical applications. It contains huge numbers of metallic fibers to produce a strong echo. However, electromagnetic (EM) scattering estimation for the chaff cloud is a challenging task since complex EM coupling between chaff elements needs to be taken into account. Actually, if the distance and the angle between two chaff elements are large enough, the EM coupling becomes ignorable. This letter presents an estimation method of the EM coupling radius to designate a region, out of which EM coupling effect can be ignored. A current attenuation formula is first proposed to indicate the relationship between the induced surface currents of any two chaff elements. Using Dijkstra's algorithm, we then find the coupling paths with the weakest attenuation. The EM coupling radius is finally determined by measuring the distance between two ends of the selected paths. Simulation results show that the averaged EM coupling radius is 3.7 times wavelength of the radar in our discussions.

Orientation Effect of the Electromagnetic Field Coupling for Device in a TEM Cell

In this article, the orientation effect of electromagnetic coupling for a device in a transverse electromagnetic (TEM) cell is explained in the frame of the model with intercoupling of equivalent electric and magnetic dipoles taken into account. Different from the widely used model, which predicts a half-circle period of the orientation effect, the proposed model predicts a full-circle period due to the introduced intercoupling. The intercoupling of the electric and magnetic field interaction inside the TEM cell and the full-circle period orientation effect is demonstrated first by simple straight and meander microstrip lines, which is then compared to a segment of an integrated circuit (IC). For the application of the proposed model to a complex device, a limited number of pairs of intercoupling electric and magnetic field dipoles can be introduced to predict the complicated orientation effect of a running large-scale IC in TEM cell measurement. The extracted dipoles are in good agreement with the near-field scanning results. The widely used Wilson model should be checked carefully in the application of field to line analysis.

Effect of inter‐electrode RF coupling on heating patterns of wire‐like conducting implants in MRI

In this study, the effects of RF coupling on the magnitude and spatial patterns of RF-induced heating near multiple wire-like conducting implants (such as simultaneous electrical stimulation of stereoelectroencephalography electrodes) during MRI were assessed. Simulations and experimental measurements of RF-induced temperature increases near partially immersed wire-like conductors were performed using a phantom with a transmit/receive head coil on a 3TMRI system. The conductors consisted of either a pair of wires or a single simultaneous electrical stimulation of stereoelectroencephalography electrode with multiple contacts, and the locations and lengths of the conductors were varied to study the effect of electromagnetic coupling on RF-induced heating. The temperature increase near a wire within the phantom was dependent not only on its own location and length, but also on the locations and lengths of the other partially immersed wires. In the configurations that were studied, the presence of a second implant could increase the heating near the tip of the conductor by as much as 95%. The level of RF-induced heating during an MR scan is affected significantly by RF coupling when more than one wire-like implant is present. In some of the configurations studied, the heating was increased by the presence of a second conductor partially immersed in the phantom. Thus, RF coupling is an important factor to consider in the assessment of safety issues for MRI when multiple implants are present.

The estimation of the electromagnetic coupling effect for the transverse isotropic laminated multi-ferroic rectangular plates

In the present work, we consider how to estimate the electromagnetic coupling effect for the transverse isotropic laminated multi-ferroic rectangular plates constituting of piezomagnetic layers and piezoelectric layer. An innovative approach is proposed to solve this problem under the assumption that the distribution of the piezomagnetic layers is small periodic. The main idea of this approach is to use the multi-scale homogenization method to obtain the 1-order approximation solutions of the original model and let the former approximate the latter. And the state-space approach is employed to obtain the exact solution for the homogenized ferroic model. For the case that each repetitive unit constitutes of two layers and the volume ratio of each layer are determined, we give some numerical examples to demonstrate that the presented method is effective in estimating the electromagnetic coupling effect of the above plates where the finite element method is used to simulate both the original model and the 1-order approximation solutions.

Near-Field Electromagnetic Coupling Effects in Optical Spectra of One-Dimensional and Two-Dimensional Arrays of Metal Nanoparticles

Near-Field Electromagnetic Coupling Effects in Optical Spectra of One-Dimensional and Two-Dimensional Arrays of Metal Nanoparticles

Research on the Coupling Characteristics of Electromagnetic Pulse of Electronic Equipment

The problem of electromagnetic interference is becoming more and more prominent in complex environment, and the study of coupling effect between electronic devices is very important to guide the design of electromagnetic protection. In this paper, CST electromagnetic simulation software is used to study the strong electromagnetic pulse coupling effect of the device chassis and harmonious vibration cavity, to simulate the coupling characteristics of the cavity by square hole seam area and the length of the outer cable in the cavity, and then to study the coupling characteristics of the two coupling methods at the same time through simulation and analysis of the coupling electric field and electromagnetic pulse simulation test. The results show that the larger the hole area, the stronger the field strength of coupling into the cavity, and no effect on the resonant point position in the cavity; The longer the cable, the stronger the field force coupled in the center of the cavity, the resonant frequency in the cavity is basically unchanged; When the two coupling methods exist at the same time, the size of the hole seam is small compared to the wavelength, which makes it difficult for electromagnetic waves to enter the inside of the cavity, mainly as cable coupling, and the other is mainly in the form of hole coupling.

A compact microstrip feedline printed antenna with perturbed partial ground plane for UWB applications

This article presents a simple compact microstrip feedline printed antenna that can minimize the consequences of frequency interference, thereby, providing good stable omnidirectional radiation pattern and transmission response within whole range of desired frequencies. The proposed antenna has two regular shaped hexagonal radiators, a mictrostrip-fed line and a partially extended ground plane perturbed by a circular slot inserted at the centre. The partial ground plane with a circular slot at the center plays an important role in the broad band characteristics of the proposed antenna, because they can adjust the electromagnetic coupling effect between patch and ground plane and improve the impedance bandwidth. The simulation and measured results are in close agreement and show that a wide bandwidth of 10.39 GHz (2.52-12.91 GHz) at −10 dBi return loss with voltage standing wave ratio less than two is achieved by this antenna. The antenna is compact (0.37λ × 0.24λ), has good radiation pattern, appreciable gain of 5.97 dBi and 134% fraction bandwidth which is favorable for ultra-wide band applications such as S, C, X, WLAN, and WiMAX. The equivalent lumped circuit model of the proposed antenna is also presented for validation purpose. The proposed antenna in particular focusses on 3.4 to 3.6 GHz frequency band with centre frequency 3.5 GHz (sub 6 GHz 5G band) and WLAN/Wi-Fi (3.6/4.9/5.9 GHz) applications.

Comprehensive analysis for influence of complex coupling effect and controllable suspension time delay on hub-driving electric vehicle performance

For in-wheel driving vehicle electric vehicles (EVs), mechanical electromagnetic coupling effect caused by the air gap deformation in permanent magnet synchronous hub motor and intensified by the road excitation deteriorates the EVs performance. In this paper, after studying the numerical method for multi-field coupling problems of hub-driving vehicle under the coupled action of electromagnetic field and mechanical field. The experimental validation is investigated. The results indicate that the multi-field coupling effect in hub-driving motor worsens the dynamics performance of the vehicle. To enhance the vehicle performance, suppress mechanical electromagnetic coupling effect and, at same time, reduce the influence of controllable suspension time delay, a delay-dependent H∞ controller is designed based on Lyapunov theory. By applying the particle swarm optimization (PSO) algorithm and the linear matrix inequality theory, the desired output controller gain is derived. Numerical simulations reflect that the active suspension controller considering control time delay not only achieves the favorable riding comfort performance and restrains the coupling effect in hub driving motor but also ensures the suspension deflection and the safety performance requirement. Moreover, it maintains the closed-loop asymptotically stability regardless of t the variation on the sprung mass and control time delay.

DoA Estimation Using Neural Tangent Kernel under Electromagnetic Mutual Coupling

Antenna element mutual coupling degrades the performance of Direction of Arrival (DoA) estimation significantly. In this paper, a novel machine learning-based method via Neural Tangent Kernel (NTK) is employed to address the DoA estimation problem under the effect of electromagnetic mutual coupling. NTK originates from Deep Neural Network (DNN) considerations, based on the limiting case of an infinite number of neurons in each layer, which ultimately leads to very efficient estimators. With the help of the Polynomial Root Finding (PRF) technique, an advanced method, NTK-PRF, is proposed. The method adapts well to multiple-signal scenarios when sources are far apart. Numerical simulations are carried out to demonstrate that this NTK-PRF approach can handle, accurately and very efficiently, multiple-signal DoA estimation problems with realistic mutual coupling.

Self-assembly of superstructures at all scales

Summary Controllable assembly of molecular and nanoscale building blocks into uniform superstructures up to bulk dimensions remains a key challenge in the next phase of nanotechnology development. Here, we report the self-assembly of superstructures at all scales by taking advantage of the partial miscibility of water and 1-butanol to generate transient aqueous emulsion droplets that can encapsulate the target materials and introduce them into template holes. Further diffusion of water into 1-butanol depletes the emulsion droplets, assembling the building blocks into one well-defined superstructure in each hole. Superstructuring of various types and shapes of nanoparticles, biomolecules, and inorganic compounds could be achieved without the need for surfactants and chemical modifications. The versatility, scalability, low-cost, and accurate positioning are crucial advantages for the future development of advanced precision manufacturing.

Electromagnetic-thermal-mechanical behaviors of a no-insulation double-pancake coil induced by a quench in the self field and the high field

High-temperature superconducting double-pancake (DP) coils wound by the no-insulation (NI) approach have been proved to have a high thermal stability and a self-protecting ability. This paper mainly studies the effect of a quench of one pancake coil on the electromagnetic-thermal-mechanical behaviors of an NI DP coil in the self field and the high field. An electromagnetic-thermal coupling quench model is used to calculate the distributions of current, temperature and electromagnetic field in the coil, and then a three-dimensional homogeneous mechanical model is built to analyze the changes in strain and stress during a quench by considering the distributions of thermal strain and Lorentz force of the coil. The results indicate that the obvious increase in circumferential current and radial current density in the bottom pancake coil is induced by a quench of the top pancake coil due to the electromagnetic coupling effect in the self field and the high field, and that the DP coil still has a negative coil voltage during a quench in different fields. Although the bottom pancake coil has a large circumferential current, the mechanical deformation of the DP coil during a quench is mainly caused by the temperature rise in the self field. The thermal expansion of the top pancake coil has a remarkable effect on the mechanical behaviors of the bottom pancake coil. Moreover, the DP coil has the same temperature rise and mechanisms of bypass current in the self field and the high field. However, the mechanical deformation of the DP coil is based on the combined effects of temperature rise and Lorentz force in the high field. It can be found that the values of the hoop and axial stresses are affected by a large electromagnetic stress.

Giant and dynamically tunable plasmonic circular dichroism in graphene ribbons and Z-shaped metal metamaterials

Plasmonic chirality has drawn a lot of attention owing to its strong and tunable circular dichroism (CD) effects and its desirable applications in bio-sensing, chiral molecules analysis, etc. In this work, the CD response in the mid-infrared region of a metamaterial consisting of Z-shaped metal array and graphene ribbons has been studied theoretically. Benefiting from symmetry breaking and electromagnetic coupling effect, the strong CD signal is generated by the metamaterial and the maximum CD value could reach 22%, which is much larger than that of reported graphene-based chiral systems. In particular, the intensity and peak position of the CD response could be dynamically controlled by the Fermi level in a large range. Meanwhile, the CD response also could be actively controlled by changing the number and the width of graphene ribbons, the distance between the graphene ribbons and Z-shaped metal array, and so on. Furthermore, the CD effect is sensitive to the ambient medium. Therefore, the graphene ribbons and metal metamaterial could be potentially utilized in bio-sensing and related fields.