分析多层介质多导体传输线的区域分解法

本文利用区域分解法 ,将直线法和有限差分法结合起来 ,用于计算多层介质中具有任意截面形状多导体传输线的电容和电感矩阵。通过在纯介质区域使用直线法 ,导体所在区域使用有限差分法分别进行求解 ,充分发挥两种方法各自的优越性。直线法中快速傅里叶变换的引入进一步提高了算法的计算效率。数值结果表明 :该方法是有效的 ,且计算时间与介质层的厚度无关。文中还研究了介质层分界面的不平整性对传输线电磁参数的影响。     

Circuit-Based Analysis of Electromagnetic Field Coupling With Nonuniform Transmission Lines

This paper presents a new algorithm for simulating electromagnetic (EM) field coupling with nonuniform multiconductor transmission lines in a circuit simulation environment. The proposed algorithm is based on the concept of passive model-order reduction, whereby an algorithmically developed passive reduced-order model, coupled with a set of equivalent sources representing the incident filed, are shown to accurately capture the behavior of the transmission line under EM excitation. The reduced-order model is developed independently from the particular shape of the incident field pulse, in the sense that, in constructing the model, one does not need prior knowledge about the waveform of the incident pulse of the EM field. In addition, it is also shown that the model developed can be used to simulate the transmission line in the absence of the EM field. The derived equivalent sources, representing the field coupling, are given directly in the time domain, thereby making simulation under nonlinear circuit terminations an easy task. Although the proposed work is aimed mainly at simulating nonuniform transmission lines, it can be applied to uniform lines as a special case. The proposed algorithm has been validated numerically with several examples.     

基于双前馈+双神经网络自适应快速反射镜的解耦控制

基于柔性铰链结构支撑和音圈电机驱动的两轴快速反射镜是一个两输入两输出强耦合系统,X轴和Y轴间的耦合大幅降低了反射镜的定位精度,采用传统的PID控制算法很难实现高精度的解耦控制。针对中心对称和轴对称结构形式的两轴快速反射镜,理论分析了两轴快速反射镜耦合来源—直流耦合分量和非直流耦合分量;建立了X轴和Y轴间的耦合物理模型;提出的双前馈+双神经网络自适应解耦控制算法分别补偿直流耦合分量和非直流耦合分量。实验结果表明:该控制算法与传统的PID控制算法相比,耦合度从5%左右降低到1.0‰以内,从而定位精度从2.5%左右提高到0.5‰以内。     

Improved tuning prediction for the microstrip coupled dielectricresonator using distributed coupling

In this paper, accurate modeling of the varactor-tuned dielectric resonator (DR) using distributed coupling between the DR and microstrip lines is investigated on the basis of three-dimensional electromagnetic study. The magnetic coupling between the DR and microstrip line is appreciable over a length greater than the diameter of the DR. The distribution of this coupling should be considered when calculating the electronic frequency tuning range. A novel circuit model is introduced to represent the coupling as distributed, with an integral method to calculate equivalent-circuit parameters efficiently. The distributed model provides much better accuracy than the conventional lumped model. A comparison is made between the calculated tuning range of 23 MHz achieved by the distributed model, which agrees closely with a measurement of 20.2 MHz, and that of 89 MHz predicted by the conventional lumped model. The circuit model of distributed coupling is, therefore, valuable in the design of DR oscillators     

Directions of arrival estimation with planar antenna arrays in the presence of mutual coupling

Directions of arrival (DoAs) estimation of multiple sources using an antenna array is a challenging topic in wireless communication. The DoAs estimation accuracy depends not only on the selected technique and algorithm, but also on the geometrical configuration of the antenna array used during the estimation. In this article the robustness of common planar antenna arrays against unaccounted mutual coupling is examined and their DoAs estimation capabilities are compared and analysed through computer simulations using the well-known MUltiple SIgnal Classification (MUSIC) algorithm. Our analysis is based on an electromagnetic concept to calculate an approximation of the impedance matrices that define the mutual coupling matrix (MCM). Furthermore, a CRB analysis is presented and used as an asymptotic performance benchmark of the studied antenna arrays. The impact of the studied antenna arrays geometry on the MCM structure is also investigated. Simulation results show that the UCCA has more robustness against unaccounted mutual coupling and performs better results than both UCA and URA geometries. The performed simulations confirm also that, although the UCCA achieves better performance under complicated scenarios, the URA shows better asymptotic (CRB) behaviour which promises more accuracy on DoAs estimation.     

Measurement of inductive coupling between coplanar superconductingtransmission lines

By measuring forward and backward coupling between superconducting coplanar transmission lines at various temperatures, we determined the dependence of inductive coupling on the London penetration depth. If the transmission lines are separated by a shielding ground line, inductive coupling increases with increasing penetration depth. If the shielding line is damaged or absent, there is a slight decrease. Since both effects are in the percentage range, they can only be observed in the forward-coupled noise signal. The backward coupled noise is nearly temperature independent. We measured inductive coupling factors between 6 and 8% on 10- and 5-μm-wide transmission lines, which are separated by a shielding ground line. Excellent agreement was obtained between measurements and FEM simulations     

阵列互耦条件下相干信源DOA估计算法研究

针对阵列互耦条件下相干信源到达方向（DOA）估计的问题,利用均匀线阵互耦矩阵的带状循环特性及对称Toeplitz性,提出了一种基于改进的空间平滑算法的信源DOA估计算法。该算法无需阵元的互耦参数信息,只需一维谱峰搜索,避免了通常多参数联合估计的多维非线性搜索及迭代运算;由于采用改进的空间平滑算法,所以该算法具有很好的统计估计性能。计算机仿真结果验证了该算法的正确性和有效性。     

Coupling Model of Crossing Transmission Lines

The coupling between transmission lines crossing diagonally is described. The resulting equations are derived by neglecting the recoupling of the line under induction (acceptor line (AL)) to the exciter line (EL). The coupling coefficients of various models are also considered. Equivalent-circuit representations for finite-length lines are obtained in two different forms: one expressed in terms of ideal voltage and ideal current sources, and the other in terms of ideal transformers, mutual inductance, and mutual capacitance. The first expressions are useful for predicting coupling between various types of lines. The second shows the coupling mechanism. The validity of the theory is confirmed by the experimental studies.     

Fast EMI Analysis via Transverse Partitioning and Waveform Relaxation

High-speed interconnects are increasingly becoming susceptible to electromagnetic interference (EMI). Hence, there is a growing need for fast simulation of interconnect lines in the presence of incident field coupling using circuit simulators such as SPICE. However, the presence of a large number of coupled lines in modern interconnect structures is a serious limiting factor in these simulations. In order to simultaneously address these difficulties, a new algorithm is presented in this paper for EMI analysis of large number of coupled interconnects. The new method exploits the recently developed waveform relaxation (WR) and transverse partitioning algorithms for fast EMI analysis. The same WR sources that are computed for multiconductor transmission line analysis are also employed for EMI analysis. The computational complexity of the proposed EMI analysis grows only linearly with the number of lines. In addition, the algorithm lends itself to parallel implementation leading to further reduction in CPU time.      

基于子空间类法的阵列误差有源校正方法

针对均匀线阵提出了一种对同时存在阵元位置误差、幅相误差及阵元互耦的阵列进行校正的方法。该方法通过旋转阵列天线得到多个校正方位的样本数据,达到多个信源独立分时校正的效果,然后通过对空时矩阵进行特征分解,得到实际阵列流型的估计值,并构造代价函数,最后采用迭代算法同时估计出所有阵列误差参数,从而实现误差的校正。计算机模拟仿真及实际阵列天线的校正实验均验证了该算法对误差参数估计的有效性和校正方法的实用性。     

多子阵互耦影响下的非圆信号自校正算法

针对多子阵互耦影响下的非圆信号波达方向(Direction-Of-Arrival,DOA)估计问题,给出了一种针对最大非圆率信号的互耦自校正算法.该算法利用均匀线阵互耦矩阵的带状、对称Toeplitz性和多子阵互耦矩阵的块状对角特性,能够与传统的互耦秩减估计器一样避免多维搜索和迭代运算.并且通过结合信号的非圆特性来扩展数据模型,使得其估计精度较传统的互耦秩减估计算法有明显提升,可分辨信源数也有所增加.对该算法的理论性能进行研究,分析了其对未知参数的可辨识性必要条件,并基于最大非圆率信号模型给出了相应的克拉美罗界(Cramér-Rao Bound,CRB).仿真结果表明,该算法较传统的互耦秩减估计算法在低信噪比、小快拍数下有更强的鲁棒性.     

Gaussian Mixture Model-Based Bayesian Analysis for Underdetermined Blind Source Separation

This paper proposes a Gaussian mixture model-based Bayesian analysis for blind source separation of an underdetermined model that has more sources than sensors. The proposed algorithm follows a hierarchical learning procedure and alternative estimations for sources and the mixing matrix. The independent sources are estimated from their posterior means, and the mixing matrix is estimated by the maximum likelihood method. Because each source is conditionally correlated with others in its Markov blanket, the correlations between them are approximated by using linear response theory; this is based on the factorized approximation to the sources' true posteriors. In this framework, each source is modeled as a mixture of Gaussians to fit its actual distribution. Given enough Gaussians, the mixture model can learn any distribution. The algorithm provides a good identification of the mixing system, and its flexibility speeds up the convergence. The iterative learning for Gaussians leads to a parametric density estimation for all hidden sources as well as their recovery in the end. The major advantages of this algorithm are its flexibility and its fast convergence. Simulations using synthetic data validate the effectiveness of the algorithm.     

A Frequency-Dependent Coupled-Mode Analysis of Multiconductor Microstrip Lines with Application to VLSI Interconnection Problems

The spectral Galerkin procedure is used to calculate the dispersion properties of multiple conductor microstrip lines. The resulting propagation constants are then used in a coupled-mode theory which demonstrates a frequency-dependent coupling of current in a five-conductor system. These results should he useful in the study of crosstalk between parallel microstrip lines used in VLSI interconnections.     

并行传输线共模泄漏的等效场-线耦合数值模型

针对并行传输线间感性和容性耦合计算问题,该文提出并行传输线等效场-线耦合亚网格时域有限差分(FDTD)数值模型,模型更适合非均匀介质等复杂情形的耦合串扰求解,且具有更为简洁的数值计算形式。利用该等效场-线耦合数值模型,对并行传输线间共模电磁信息泄漏进行模拟仿真和实验测试,时域模拟和频域实验结果均表明,该模型可以有效刻画并行传输线共模电磁信息泄漏发射特性。     

Direction finding in the presence of mutual coupling

An eigenstructure-based method for direction finding in the presence of sensor mutual coupling, gain, and phase uncertainties is presented. The method provides estimates of the directions-of-arrival (DOA) of all the radiating sources as well as calibration of the gain and phase of each sensor and the mutual coupling in the receiving array. The proposed algorithm is able to calibrate the array parameters without prior knowledge of the array manifold, using only signals of opportunity and avoiding the need for deploying auxiliary sources at known locations. The algorithm is described in detail, and its behavior is illustrated by numerical examples     

含有受控源的线性电路的叠加原理研究

用叠加原理分析计算含有受控源的线性电路时,独立源可以单独作用,受控源是不能单独作用的。因为受控源单独作用只能求出与控制量有关的未知量,不能计算出具体值,具体值需要通过应用叠加原理才能计算出来,这是不符合叠加原理概念的。但是受控源单独作用作为一种计算方法还是可以的。     

Fast transient analysis of incident field coupling to multiconductor transmission lines

Due to the rapid surge in operating frequencies and complexity of modern electronic designs, accurate/fast electromagnetic compatibility/interference analysis is becoming mandatory. This paper presents a closed-form SPICE macromodel for fast transient analysis of lossy multiconductor transmission lines in the presence of incident electromagnetic fields. In the proposed algorithm, the equivalent sources due to incident field coupling have been formulated so as to take an advantage of the recently developed delay extraction based passive transmission line macromodels. Also, a method to incorporate frequency-dependent per-unit-length parameters is presented. The time-domain macromodel is in the form of ordinary differential equations and can be easily included in SPICE like simulators for transient analysis. The proposed algorithm while guaranteeing the stability of the simulation by employing passive transmission line macromodel, provides significant speed-up for the incident field coupling analysis of multiconductor transmission line networks, especially with large delay and low losses.     

Analysis of mode coupling on guided-wave structures using Morsecritical points

New insight on mode coupling in waveguiding structures is obtained from the theory of Morse critical points (MCP's). It is shown that the traditional coupled-mode formalism has a clear analytical connection with functional properties of the characteristic determinant in the vicinity of the Morse critical point, which determines the minimum of coupling. The relationship between perturbed and independent modes in the mode-coupling region is obtained using the Taylor polynomial of order two about the Morse critical point, and it is found that the coupling factor is proportionally related to the value of a characteristic function at this point. The qualitative modal behaviour in the mode-interaction region is predicted by a simple normal form, which can be geometrically interpreted as a result of the intersection of a saddle surface and a plane corresponding to the minimum of the coupling factor. Numerical results for a variety of guided-wave structures, including printed-circuit transmission lines, planar-slab waveguides, and shielded microstrip-like lines demonstrate the efficiency of the proposed approach for the rapid identification of mode-coupling regions, and for reconstruction of dispersion behaviour in those regions via simple analytic (normal) forms     

高速集成电路中多导体传输线的电磁参数提取与瞬态响应分析

本文在直线法中引入了一种新技术，将多层介质多导体结构的各层介质等效为级联的坪端口网络，介质层间导体等效为端口的电流源，从而大大简化了公式推导，方便了编程计算。     

基于FDTD方法的车载天线耦合特性分析

本文采用FDTD法对处于地面附近的车载通信天线的电磁兼容性进行了分析计算.克服传统方法存储量大,计算困难等缺点,并提高了计算速度和精度.文章最后以某军通信车为实体建模,计算仿真了车上3副天线的耦合度.所用方法及所得结果可作为通信率电磁兼容分析与设计的手段和依据.