Electromagnetic Field Coupling Research Articles

English

Many applications of micro strip antenna are constricted by their innate narrow bandwidth. In this paper a survey on the different feeding technique, which are micro strip line feed, coaxial plane feed, proximity coupled feed and aperture couple feed, for wireless micro strip antenna is done. Micro strip line and coaxial probe feeds are contacting scheme, in which RF power directly to the radiating patch. Proximity and Aperture coupled feeds are non contacting schemes, in which electromagnetic field coupling is done to transfer power between the micro strip line and the radiating patch. In this paper, a new approach is projected to design inset feed micro strip antenna with slots in it to develop the antenna bandwidth. The input impedance matching method for antenna is predominantly vital for a feed technique. The design of slotted micro strip antenna on a substrate of thickness 11mm that give wideband features is based on embedding an inset look analogous proximity L shape feed to improve bandwidth. The Method of Moments (MOM) base IE3D software with the method of moment (MOM) ensemble has been used to in the circular patch performance comparison for the improvement of the impedance bandwidth and the power radiated with slots on the same physical dimensions.

Numerical calculation of shielding effectiveness of enclosure with apertures based on EM field coupling with wire structures

Shielding effectiveness of a protective metal enclosure with apertures and receiving antenna placed inside is numerically considered. The purpose of the antenna, here considered as a dipole, is to detect the electromagnetic (EM) field level within the enclosure and to transfer this information via a coaxial cable to a network analyzer. This follows the experimental procedure used to measure the shielding effectiveness of enclosure. A numerical model, based on the Transmission-Line Matrix (TLM) method enhanced with so-called wire node, is used to simulate this dipole antenna/cable arrangement in order to investigate how much it disturbs the level of shielding effectiveness due to their two-way coupling with EM field inside the enclosure. The numerical model, whose accuracy is proved by comparison with experimental results available in the literature, is used to consider the influence of radius and length of the dipole-receiving antenna and the impact of cable presence on the distribution of EM field inside the enclosure and shift of resonant frequencies for normal and oblique incidence.

VIA-HOLE LESS BROADBAND CONDUCTOR-BACKED COPLANAR WAVEGUIDE TO COUPLED MICROSTRIP TRANSITION UP TO 40 GHZ

A broadband via-hole less transition from a conductor-backed coplanar waveguide (CBCPW) to a parallel coupled microstrip line (CMS) via microstrip section (MS) is reported in this paper that is realized on a MCL FX-2 substrate (100 μm thick). This transition should find a wide variety of applications due to its demonstrated broadband (from 4.5 GHz up to 39.5 GHz) behavior, ease of fabrication, and low manufacturing cost. In addition, utilization of the MS section between the CBCPW and CMS sections allows putting ground electrode in a different plane than the signal electrodes. This exibility made possible by electromagnetic field coupling between the bottom and top ground planes simplifies the transition manufacturing and facilitates the characterization of optical components driven with CMS line using coplanar probes.

Coherent resonance of quantum plasmons in the graphene-gold cluster hybrid system.

Noble metal nanoparticles can modify the optical properties of graphene. Here we present a detailed theoretical analysis of the coherent resonance of quantum plasmons in the graphene-gold cluster hybrid system by using time dependent density functional theory (TDDFT). This plasmon coherent effect is mainly attributed to the electromagnetic field coupling between the graphene and the gold cluster. As a result, the optical response of the hybrid system exhibits a remarkably strong, selectable tuning and polarization dependent plasmon resonance enhanced in wide frequency regions. This investigation provides an improved understanding of the plasmon enhancement effect in a graphene-based photoelectric device.

A Foster-Type Field-to-Transmission Line Coupling Model for Broadband Simulation

A passive and inherently stable multiport equivalent circuit for lossy transmission lines is presented. The convergence of the infinite modal representation is accelerated by appropriate inductances, for which an exact closed-form expression is developed. The order number of the truncated modal circuit is estimated by a simple relation, according to the required signal bandwidth. The coupling of arbitrary external electromagnetic fields is incorporated by a limited number of corresponding modal sources. The accuracy and versatility of the suggested SPICE-compatible equivalent circuit is demonstrated by examples in frequency and time-domain, including nonlinear terminations.

An Equivalent Two-Port Model for a Transmission Line of Finite Length Accounting for High-Frequency Effects

The aim of this paper is the definition of an equivalent two-port model of a transmission line that is able to take into account high frequency radiation effects. Such a model is particularly useful when one has to represent the line into a more complex power system, modeled in a lumped way. To reach this goal, it is necessary to produce a reliable and computationally effective solution to the problem of the high-frequency electromagnetic field coupling with a terminated transmission line. From a mathematical standpoint, this problem can be presented by means of an integral equation whose solution can be achieved with regularization procedures for linear inverse problems. In order to obtain a computationally efficient result, the unknown current is first developed in a Fourier series and then the Landweber iterative algorithm is applied to identify the series coefficients. The proposed method is then tested taking as reference the numerical results obtained using the Numerical Electromagnetics Code (NEC-2), reaching a good agreement.

Electromagnetic response of strongly coupled plasmas

We present a thorough analysis of the electromagnetic response of strongly coupled neutral plasmas described by the gauge/gravity correspondence. The coupling of the external electromagnetic field with the tower of quasi-normal modes of the plasmas supports the presence of various electromagnetic modes with different properties. Among them we underline the existence of negative refraction with low dissipation for a transverse mode. Previous hydrodynamical approaches have shown the ubiquitous character of negative refraction in charged plasmas and the absence thereof in neutral plasmas. Our results here extend the analysis for neutral plasmas beyond the hydrodynamical regime. As an application of these new insights we briefly discuss the case of the quark gluon plasma in the temperature dominated regime.

Coupled Electromagnetic and Thermal Field Modeling of a Laboratory Busbar System

Coupled Electromagnetic and Thermal Field Modeling of a Laboratory Busbar System

Experimental and numerical study of the effect of coil structure on induction nitriding temperature field

The axial and radial temperature distributions of an induction heating workpiece considerably impact the subsequent nitriding process. To obtain a satisfactory temperature distribution, an equal pitch coil, a variable pitch coil, and a variable radius coil were designed. Furthermore, an induction heating model that exhibits electromagnetic and temperature field coupling was established; thus, the effects of the current density and frequency on the heating efficiency and temperature distribution of the workpiece were analyzed and compared. In addition, an induction heating experiment was conducted to verify the model. According to the numerical results, the variable radius coil can reduce the axial temperature difference in comparison with equal pitch coil and variable pitch coil. Hence, the workpiece heated using the variable radius coil can achieve a better temperature distribution when compared with those heated by the equal pitch coil and variable pitch coil, with appropriate current density and current frequency values.

A New Approach in Optimizing the Induction Heating Process Using Flux Concentrators: Application to 4340 Steel Spur Gear

The beneficial effects of using flux concentrators during induction heat treatment process of spur gears made of 4340 high strength steel is demonstrated using 3D finite element model. The model is developed by coupling electromagnetic field and heat transfer equations and simulated by using Comsol software. Based on an adequate formulation and taking into account material properties and process parameters, the model allows calculating temperature distribution in the gear tooth. A new approach is proposed to reduce the electromagnetic edge effect in the gear teeth which allows achieving optimum hardness profile after induction heat treatment. In the proposed method, the principal gear is positioned in sandwich between two other gears having the same geometry that act as flux concentrators. The gap between the gear and the flux concentrators was optimized by studying temperature variation between the tip and root regions of gear teeth. Using the proposed model, it was possible identifying processing conditions that allow for quasi-uniform final temperature profile in the medium and high frequency conditions during induction hardening of spur gears.

The Electromagnetic Flanging of a Large-Scale Sheet Workpiece

In this paper, an electromagnetic forming (EMF) system with an energy of 200 kJ (25 kV, 640 μF) was designed and fabricated to flange a large-scale aluminum alloy sheet with bore, whose outer diameter, bore diameter, and sheet thickness are 640 mm, 180 mm, and 5 mm, respectively. The stress distribution of the midplane of the coil was calculated to check the coil structural strength. And a multiphysics coupled finite element model, which involves the coupling of circuit, electromagnetic field, deformation field, and thermal field, was built to assess the forming capacity of the EMF system. Furthermore, the experimental results of electromagnetic flanging in the case of 155 kJ are presented and compared with the numerical results. Both the simulation forming depth 87 mm and experiment forming depth 90 mm show that the EMF system is effective to form the large-scale sheet workpiece.

A Novel Route to Surface‐Enhanced Raman Scattering: Ag Nanoparticles Embedded in the Nanogaps of a Ag Substrate

An intense surface‐enhanced Raman scattering (SERS) effect is realized by depositing Ag nanoparticles (NPs) into the nanogaps of a Ag substrate. The nanogaps are formed by the thermal annealing of a Ag film on a silicon substrate. This SERS substrate has an enhancement factor (EF) of 2.3 × 106 and a strong signal enhancement that is 20 times higher than that of substrates without the Ag NPs within the nanogaps. Moreover, the reproducibility is improved with the decreased relative standard deviation of mapping data, which falls from 23.9% down to 12.1%. Its performance is as good as commercial substrates. The electromagnetic distribution between the nanoparticles and nanogaps is simulated by the finite‐difference time‐domain method, which suggests that the additional enhancement of the SERS effect can be mainly attributed to the remarkable increase of the local electromagnetic field coupling among the Ag NPs, which is at least 12 times higher than that of conventional samples with bare Ag NPs.

전기철도에서의 통신선 유도전압에 대한 금속관 차폐효과 측정

전기철도 선로변에 포설되어 있는 통신선에는 유도전압이 발생하여, 통신품질 저하와 기기 오작동 및 안전문제를 유발할 수 있다. 이와 같은 유도전압은 전차선과 통신선의 자계결합에 의해 유발되며, 구조물이나 레일 등의 금속물이 근처에 있을 경우 차폐영향을 받는다. 본 논문에서는 통신선 주변에 금속관이 매설되어 있을 경우에 발생하는 차폐효과를 실험을 통해 정량적으로 분석하였다. 고속철도 현장에서의 실험 결과, 금속관이 통신선으로부터 1~2m 거리에 병행매설되어 있을 경우, 금속관의 차폐효과는 20% 정도인 것으로 측정되었다. 또한, 이격거리가 4m 이상인 경우에는 차폐효과가 1% 이내로 미미하다는 것을 확인하였다. 이상의 결과는, 수도관이나 가스관, 구조물의 철근과 같은 금속 설치물의 차폐효과를 분석하는 데 활용할 수 있다. Electric railway induces interference voltage on wayside communication cable which brings about communication errors, malfunction of devices, and safety problem. The magnitude of the induced voltage depends on the electromagnetic field coupling which is affected by metallic installations such as rail and track structures. This paper provides an experimental analysis of the screening effect of metallic pipe on the inductive voltage caused on communication cable. The measurements at a high-speed rail site show that the screening effect of metallic pipe is about 20% when the separation distance between the pipe and communication cable is 1~2 m. The screening effects is less than 1% and can be neglected when the separation distance is more than 4 m. These results are useful to evaluate the screening effects of the metallic installations such as water pipe, gas pipe, and reinforcing bar.

Self-Shielded Circularly Polarized Antenna-in-Package Based on Quarter Mode Substrate Integrated Waveguide Subarray

A self-shielded antenna-in-package (AiP) covering IEEE 802.11a band is proposed in this paper, and the antenna is designed using quarter mode substrate integrated waveguide (QMSIW) subarray technology. Electromagnetic interference (EMI) in a system-in-package integrated with AiP is discussed firstly. Electric field distribution of the proposed AiP is simulated, and it shows that the metallic via-holes array in the QMSIW subarray approximates to the electric wall to isolate the electromagnetic field coupling and then to increase the EMI shielding. The operating principle of the proposed antenna is investigated through an isosceles right triangular waveguide. An antenna prototype is fabricated and measured. The measured results match with the simulated and analyzed results very well. It is demonstrated that the proposed QMSIW subarray with metallic via-holes array gives an attractive and promising way to design the AiP with self-shielded property.

Modeling Acoustic Effects During Casting Nanocomposites Under Electromagnetic Field

Casting is one of the most cost-effective methods of producing metal matrix nanocomposites. However, it is extremely difficult to disperse nanoparticles uniformly in a metal matrix due to their large surface-to-volume ratio and their low wettability in liquid metal, which cause their agglomeration and clustering. This paper presents a model of the process of nanocomposite casting where an alternating electromagnetic field is used to induce a standing acoustic wave in the molten metal. The model requires a coupling of electromagnetic field, metal flow field, and acoustic field. It allows optimization of the parameters of the coil supply so as to produce a cavitation phenomenon in the metal, which breaks up the agglomerations of nanoparticles.

Analysis of Electromagnetic Field in a Modular Joint

Electromagnetic components with coils, soft and hard magnetic materials of different power are assembled in modular joints, the coupling of magnetic fields in which has impact on other electrical components. The electromagnetic field of joint studied in this paper is mostly from the motor and safe brake. Firstly, the electromagnetic field of torque motor is analyzed by 2D model, the electromagnetic fields produced by coil current and permanent magnet are compared, the results show that the field produced by coil is much smaller, which can be omitted in the 3D model. The coupling electromagnetic field of torque motor and safe brake is analyzed by simplified 3D model; the field distribution curve is built with position change. Calculating the field distribution can be used to properly design the placement of electrical components such as sensors to avoid the magnetic interference. The experiment shows that adjusting the position according to the analysis results can solve the problem of magnetic encoder instability.

Surface plasmon resonance: signal amplification using colloidal gold nanoparticles for enhanced sensitivity

Among all the detection methods developed for bioassays, optical-based approaches are the most popular techniques. A widely used and accepted bioanalytical technique for routine characterization of molecular recognition events at a solid interface is surface plasmon resonance (SPR) spectroscopy. Compared with other techniques, SPR offers a series of advantages including rapid and real-time analysis, in situ detection, and the possibility to determine kinetic as well as thermodynamic parameters of interacting partners without the requirement of tagging one of the two partners. This method is nowadays used in academic and industrial research laboratories for drug discovery processes, safety, and quality control applications as well as for understanding bioaffinity reactions. Past studies have shown that SPR can detect approximately 100 ng/l of proteins. Currently, much effort is still invested to further improve SPR with respect to the sensitivity in the detection of low molecular weight analytes as well as in the detection limit for different analyte/ligand reactions. This review will focus on the use of gold nanoparticles as an amplification strategy in SPR sensing. Compared to other review articles highlighting the several synthetic routes and properties of gold nanoparticles and research utilizing gold nanoparticles for various sensing strategies, this review will exclusively look at the impact of gold nanostructures for ultrasensitive SPR sensing. Signal enhancement by gold nanoparticles is caused by several effects such as surface mass increase due to enhanced surface area, larger refractive index changes by the particle mass, themselves, and electromagnetic field coupling between the plasmonic properties of the particles (localized surface plasmon resonance) and propagating plasmons. The unique optical, electronic, and catalytic properties of gold nanoparticles put them into the forefront of interest for signal amplification as will be outlined here.

Coaxial cable Bragg grating assisted microwave coupler

This paper reports a microwave coupler based on two parallel coaxial cable Bragg gratings fabricated by drilling U-grooves across the cables at periodic distance along the cable direction. Electromagnetic field couplings between two cables were observed at discrete frequencies through both near and far ends detections. The coupling frequency and strength can be precisely controlled by varying the grating period and length. The coupling bandwidth may also be controlled through specific grating design. The device physics was also described through transfer matrix which matched well with the experimental results.

Split-Ring Slot in the Broad-Wall of a Rectangular Waveguide

Recently the Slotted Waveguide Antenna Stiffened Structure (SWASS) was introduced, where an antenna array is incorporated as an integrated part of a load bearing structure. The array element spacing and individual radiating element sizes play a critical role in the overall mechanical strength of the structure. These parameters are constrained by Slotted Waveguide Antenna (SWA) array design, and the coupling of the waveguide electromagnetic fields to the radiating apertures. In this letter, the radiation characteristics of a split-ring slot in the broad-wall of a rectangular waveguide are investigated for the first time. The simulated and measured results show that the split-ring slot radiates a linearly polarized wave with a total efficiency and realized gain close to those of conventional rectangular slots. The proposed split-ring slot has an outer diameter of $0.186 \lambda _{0}$ , a significant size reduction compared to a traditional $0.5 \lambda _{0}$ rectangular slot and the previous limit of $0.25 \lambda _{0}$ for metamaterial loaded rectangular slots. The reduced aperture size of the split-ring slot alleviates the impact of the radiating elements on the mechanical strength of the structure.

Single-contact transmission for the quasi-wireless delivery of power over large surfaces

A method of power transmission is proposed that delivers power through the resonance of a helical receiver with its surrounding stray capacitance. The system operates in a quasi-wireless state where power is transferred over a single connection to a surface much larger than the dimensions of the receiver. This ensures high-efficiency energy transfer over large areas without the need of strong coupling electromagnetic fields. Standard power connectors such as tracks, plugs, and cords may be easily replaced with conductive surfaces or objects such as foil sheets, desks, and cabinets. Presently, the method is experimentally demonstrated at the small scale using loads of up to 50 W at an efficiency of 83% with both bare and insulated surfaces. Simple circuit modeling of the system is presented which shows close agreement with experimental results.