Research on the macro effect of the thin wire array in metamaterial by equivalent circuit method

A novel compact left-handed (LH) microstrip transmission line is presented. To establish a negative permeability and permittivity, the transmission line is loaded with step impedance resonators (SIRs) and an array of thin wires on dual-layer architecture. Compared to existing LH structures, which incorporate conventional split ring resonators (SRRs), the proposed structure is three times smaller in size whilst achieving the same performance. To illustrate the electromagnetic properties of the metamaterial, both analytical and full wave analysis were performed and utilized to determine the effective electromagnetic parameters of the proposed structures. The experimental results show that a microstrip line periodically loaded with SIR only produces a rejection of −6 dB at a resonant frequency of 5.50 GHz. The results also indicate a pass-band response for a left-handed microstrip line (LHML) constructed from SIR and thin wire arrays at the same resonant frequency.

Mode matching method and equivalent circuit method are the two main waveguide filter design methods. The mode matching method have well calculation accuracy, especially when the waveguide size is relatively large compared with operating wavelength, but this method does not provide physical insights, therefore traditional filter design theories and methods cannot be applied. However, in most of the engineering applications, the size of the waveguide filter is not large to prevent higher-order modes from affecting the performance of the entire system. Under this condition, the equivalent circuit, providing physical insight, and efficient with acceptable accuracy, becomes the preferred method when designing waveguide filters. Unfortunately, the equivalent circuit of the waveguide filter that has been established so far is realized by connecting multiple Y-parameter elements with transmission lines. This method does not show the internal structure of the waveguide filter cavity, so in fact it cannot provide physical insight. Moreover, compared with the mode matching method, the reduction of the calculation amount is also very limited. This paper gives the complete equivalent circuit model of the waveguide filter with analytical expressions for the first time. The establishing process of equivalent circuit represents by capacitors and inductors are given in detail by taking circular waveguide filter excited by TM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> mode as an example. The effectiveness of the proposed method is verified by finite element simulations and experiments.

The problem of coupling between the transmission line and the external electromagnetic waves is analyzed more easily and more effectively if it is treated via transmission line theory rather than scattering theory if the cross section of the transmission line is much smaller than the wavelength and the principal mode of the induced current is TEM. This paper derives the transmission line equations by which the induced current is excited by the electric field components in the transmission direction and between the lines among the electromagnetic field components. the relation with the conventional theory, physical meanings and the equivalent circuits are discussed. In the experiment in which a plane wave is used as the external electromagnetic field, the results agree well with the present theory and the validity of the theory is confirmed if the transmission line cross section is extremely small. Further, a compensation method is discussed for the transmission line height for which the principal mode is considered TEM. the theoretical accuracy is shown and the fact that the line width restricts the range of applicability of this theory is confirmed experimentally.

Antennas receive the power from free space and transmit it to the loads. In this process, antennas are like power supplies with impedance. So the equivalent circuit method can be used to study receiver antennas. From the equivalent receiver circuit of dipole antennas, the relationship between dipole antennas as scatters and as radiators is found. The radar cross-section (RCS) expressions of resonant dipole antennas with arbitrary loads are obtained from the relationship. These RCS expressions are not only used to study the scattering properties of dipole antennas, but also to calculate the RCS values of an ideal dipole with arbitrary loads, e.g. short, open or match circuit. The results calculated are consistent with the ones simulated by HFSS.

Introduction: Electromagnetic wave coupling to transmission lines has received much attention for many years. This classical EMC problem has recently evolved from deterministic models to statistical analysis [1]. This latter approach has been shown to be more suited to the modelling of realistic situations when transmission lines are immersed in diffused wireless communication systems. In the related works, the localisation and polarisation of the interference sources are considered as random variables, and closed form expressions or numerical approximations are derived concerning the statistical distribution of the induced voltage. A usual limitation of this approach is however the single interference source assumption leading to a single interference field impinging the lines. In confined situations, dense multipath environment, or when several transmitters are present, a better modelling might be obtained by considering a more complex excitation of the lines. In this Letter, a general formalism based on a plane wave spectrum illumination is proposed to study such a case. Formalism: Let a uniform and lossless bi-filar transmission line be located at the origin of a Cartesian co-ordinate system. The line is directed along the z axis, the spacing between the conductors is b ,t he conductor radius a, and the line length s. At z ¼0, the line is fed by a sinusoidal source V0 of impedance Z0. At the far-end, a load impedance Zs terminates the line. Using transmission line theory, the current flowing on the line is given by

The vast majority of nonuniform transmission lines are no analytical solution except for a few special forms of transmission line. Dividing nonuniform transmission line into several equal parts, then each part can be regarded as uniform transmission line approximately. Using the theory of uniform transmission line to analyze nonuniform transmission line's transient response is the commonly used method. Composite Simpson's rule for transient analysis of nonuniform transmission lines is proposed in this paper. The exponential transmission matrix of nonuniform transmission line's equation is transformed into a general algebraic equation, which greatly simplifies the analysis on transient response for nonuniform transmission line. The simulation results illustrate the accuracy of the presented approach with examples.

Cooperating with secondary protection system, DC circuit breakers are used to deal with direct current (DC) faults in low voltage DC distribution system. To realize ultra-fast operating of DC breakers, optimization based on simulation of coil-coil type electromagnetic repulsion actuator (EMRA) is discussed in this paper. Considering exiting simulation based on finite element method (FEM) is quite time-consuming, an equivalent circuit method (ECM) for the Coil-Coil type EMRA is established. In the equivalent circuit equation, lumped equivalent inductance which contributes to the induced electromotive force (EMF) is used to reflect the coupling effect of distribute electromagnetic field on electric circuit, the gradient of equivalent inductance which contributes to the motional EMF reflecting the coupling effect of mechanical motion on electric circuit and the equivalent resistance that varies with temperature reflecting the coupling effect of temperature field on electric circuit. The lumped equivalent inductance and its gradient are extracted by solving static magnetic field based on FEM. By solving the state equations, the transient electrical and operating characteristic of EMRA are obtained. In the end, the results of the model based on ECM are compared with FEM, and as expected, they are in good consistence.

Modeling of a millimeter wave planar Schottky diode using both improved equivalent circuit model and 3D-EM model

A comparison between the equivalent circuit model and moment method was done. Numerical results were obtained with the equivalent circuit model using Matlab routines and with moment method using the Ansoft Design <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">¿</sup> software. Experimental results obtained from literature were compared with numerical results. A good agreement was observed. Two dual band geometries were considered: the Jerusalem cross and the double square loop. The parameters used to comparison were analytical complexity, accurate, and computational effort. For this last parameter and considering the worst case, the equivalent circuit method was run in 55 ms, while the method of moments took around 4 hours.

The structure and working principle of a new hybrid magnetic bearing is introduced in this paper. To overcome the drawbacks of finite element method(FEM) in parameter design of hybrid magnetic bearing, a method based on the equivalent magnetic circuit method is proposed. The calculating equation and procedure for all parameters of the hybrid magnetic bearing are deduced in detail. The feasibility of the proposed method is verified through an example and the influence of the air gap length on other parameters is studied. The distribution of magnetic flux in the air gaps calculated by ANSYS is in good agreement with the design goal, which validates the proposed method.

AC magnetic bearings have potential application prospects in high speed situations and low-speed lustration conditions with the advantages of no friction, no wear, no oil lubrication, seals, and low cost, low loss, long life and so on. For overcoming the shortcomings of modeling on radial suspension forces for AC magnetic bearing, such as imprecise model, and lack of directness and generality, a new radial suspension forces modeling method of AC magnetic bearing based on Maxwell tensor method is proposed in this paper, which makes modeling process accurate, direct and universal. The mathematical model of suspension forces for two degrees of freedom of AC hybrid magnetic bearing (HMB) is established with this proposed method, whose expression of suspension forces is proven to in accordance with the expression established by equivalent magnetic circuit method, (the only difference is the coefficient between them), so the correctness of the model and the feasibility of the method are verified by the results. Finally, the control block diagram of experimental system according to this model of two degrees of freedom AC HMB is presented and some related experiment is designed. The correctness of the suspension forces mathematical models of two degrees of freedom of AC HMB is verified by the experiment and the experimental results show that the proposed modeling method is more accurate than the equivalent magnetic circuit method.

Spin wave resonance in Ni81Fe19/Pt thin wire arrays has been investigated using the inverse spin-Hall effect (ISHE). The spin wave in the Ni81Fe19 layer drives spin pumping, generation of spin currents from magnetization precession, and the pumped spin current is converted into a charge current by ISHE in the Pt layer. We found an electromotive force transverse to the spatial and the spin-polarization directions of the spin current. The experimental results indicate that the amplitude of the electromotive force is proportional to the spin wave resonance absorption intensity, enabling the electric measurement of spin wave resonance in nanostructured magnetic systems.

SummaryThe high level of integration has made the analysis and design of integrated circuits and packages increasingly challenging. Hence, there exists an urgent need to reduce the computational complexity of existing numerical methods. The integral equation‐based method known as the partial element equivalent circuit (PEEC) method naturally generates an equivalent circuit that can be analyzed in both the time and frequency domains. The enforcement of Kirchhoff laws to the equivalent circuit may easily result into a very large set of equations whose solution can be extremely time‐consuming.In this paper, we propose a vectorized version, over the frequency sweep, of the adaptive cross approximation algorithm. Furthermore, the multiscale block decomposition is applied to the PEEC method, powered by a vectorization strategy and an efficient management of the random access memory. It is found that the proposed use of vectorization and compression techniques in the framework of the multiscale block decomposition results in a significant computational speedup of the frequency‐domain analysis of PEEC models. The efficiency and accuracy of the proposed method are demonstrated through its application to two pertinent problems. Copyright © 2014 John Wiley &amp; Sons, Ltd.

PurposeThe purpose of this paper is to model and analyze energy transfer through near‐field resonant coupling for high power light‐emitting diode (HPLED) illumination, with the intention to increase the appreciation and use of the coupled mode theory (CMT) other than the usual equivalent circuit method.Design/methodology/approachThe CMT is extensively used to analyze the wireless energy transfer system because of its generality, simplicity, accuracy and intuitive understanding of near‐field resonant energy coupling mechanism.FindingsThe CMT forms a general way to model and analyze the non‐radiative magnetic resonant coupling systems. It is suitable not only for low frequency coupling but also for high frequency (of million‐Hertz) in which the circuit parameters are not easily obtained. Optimal coupling condition corresponding to the maximum power transfer is identified based on the CMT, and the multiple limit cycle phenomenon caused by the nonlinear nature of the HPLED is also described on the CMT model.Originality/valueThis paper takes advantages of CMT, i.e. generality, simplicity, accuracy and intuitive understanding to analyze the near‐field resonant energy coupling system. Key characteristics of the systems are explored based on the CMT, not the usual equivalent circuit method. The influence of nonlinear nature of the high power LED on energy transfer is also investigated. This work seeks a more general way than conventional equivalent circuit method to model and analyze the resonant magnetic system and the results obtained could facilitate better understanding of the resonant magnetic coupling mechanism and optimal design of the near‐field energy transfer system.

Guided localized electromagnetic waves propagating along 1D arrays of thin metallic parallel wires, finite and infinite, are studied. The array of thin PEC wires is embedded in the upper dielectric half-space close to the interface separating two dielectric media with different permittivities. In the first part of the work we study dependence of resonance frequencies of localized modes excited by a finite array of parallel thin wires illuminated by normally incident plane electromagnetic wave with respect to the array height over the interface. Due to the symmetry only two main modes are excited. It is important that when the height of the array becomes sufficiently small the order of the resonance modes changes. We apply numerical analysis based on the Pocklington system of integral equations to compute resonance frequencies and construct excited localized modes above the array. We also compare our results against computations obtained by means of another independent numerical model.