低信噪比双基地MIMO雷达目标角度跟踪算法

研究了低信噪比时双基地MIMO雷达目标跟踪问题,提出了一种基于改进AAJD（Adaptive Asymmetric Joint Diagonalization）的目标跟踪算法.首先,对AAJD算法进行改进,得到与特征值作用相同的变量,从而找出大特征值变量对应的特征矢量,解决了低信噪比时AAJD算法信号子空间扩展问题.其次,在非稳定跟踪状态时消除特征值变量误差积累的影响,得到更加准确的信号子空间,并对ESPRIT算法进行改进,实现收发角度的配对和相邻时刻角度的自动关联.仿真结果表明改进AAJD算法低信噪比时能够实现角度跟踪,且收敛速度和稳定性能明显优于AAJD算法.     

传输线理论在信号完整性问题中的应用

信号完整性问题是目前高速数字设计领域最重要的问题之一。近年来的设计实践表明:大多数的电路板都或多或少的涉及到这个问题,电路板中的PCB走线可基本看作是一种特殊的无损传输线。故根据传输线的理论,可以分析、研究高速PCB板走线的信号特性,并找出解决信号完整性的方法。通过对该理论的研究,对当前最常用的2种解决方案源端匹配和末端匹配,做出了详尽的理论解释和优劣对比。     

A new method for the analysis of integrated transmission lines

A flexible and efficient technique for the analysis of transmission lines is described. The transmission line is considered as the union of « elementary waveguides », where the medium is uniformly stratified. The modes are determined by matching the field at the interfaces using a procedure that leads to a linear eigenvalue problem involving a limited number of variables.     

Propagation of TM modes in a circular dielectric waveguide filled with a medium with Kerr nonlinearity

Eigenmodes propagating in a cylindrical dielectric waveguide of circular cross section filled with a nonlinear medium whose nonlinearity is described by the Kerr law are analyzed. The nonlinear eigenvalue boundary problem for the nonlinear Helmholtz equation is considered. An iterative numerical method for obtaining the approximate solutions is developed. Numerical results are presented.     

A General Approach to Guidance in General Two-Dimensionally Periodic Medium

Based on Floquet theorem and Maxwell equations, eigenvalue problem for general two-dimensionally periodic (2DP) medium is rigorously solved. The dispersion relation for piecewise uniform (PU) 2DP medium is derived in most general analytic formulations to suit all kinds of Dielectric Waveguide Array (DWA) configurations. Numerical results for a particular rectangular DWA are compared and shown to be in exact agreements with those obtained by previous different way, but recent method is much more universal and with much better simplicity and accuracy.     

改进的自适应呼吸信号均值漂移跟踪方法研究

利用呼吸门控技术进行放射治疗已成为一个热门研究问题,它能确保对健康组织细胞造成最小程度的伤害,而其中的关键问题之一是研究呼吸信号均值漂移跟踪方法,以保证门控技术在开关放射线方面的准确性。本文基于Kanatani高精度椭圆拟合分析方法,并在广义特征分解问题基础上,提出了一种改进的自适应呼吸信号均值漂移跟踪方法,利用我们提出的改进算法可以在状态空间中用椭圆对呼吸信号进行估计。在本文中我们可以得到椭圆的中心值,它对应于我们所要估计的呼吸信号均值,其对有信号损失的数据以及伪数据都具有鲁棒性,在实验中我们验证了由于利用了Kanatani提出的方法,对小数据量信号进行估计时,我们的算法同样具备良好的抗噪性,这修正了仅利用广义特征分解问题中寻找对应特征向量的最大特征值方法求解椭圆估计参数方面的不足。      

Sparse matrix eigenvalue solver for finite element solution of dielectric waveguides

A method is presented to find a selected set of eigenvalues and the respective eigenvectors of the generalised eigenvalue problem Ax= lambda Bx for large, sparse, real or complex, nonHermitian matrices. Although the method is clearly applicable to other problems, results are given of application to the vectorial finite element analysis of dielectric waveguides.<>     

Numerical analysis of surface wave on microstrip antenna with lossysubstrate

The key to analysing a guided surface wave is to solve its eigenvalue equation. When the medium is dissipative, the eigenvalue equation is a complex transcendental equation. The Kuhn algorithm is applied to work out the eigenvalue equation     

Domain-integral analysis of channel waveguides in anisotropicmultilayered media

A domain-integral equation method is presented to determine both propagation constants and the electromagnetic field distributions of guided surface wave modes in integrated optical waveguides. Both the waveguide and its multilayered embedding are anisotropic. The permittivity tensor of the embedding is assumed to be piecewise homogeneous. The kernels of the domain-integral equations consist of Green's tensors. The integral equations form an eigenvalue problem where the electric field strength represents the eigenvector. This problem is solved numerically by applying the method of moments. Numerical results are presented for an anisotropic ridge waveguide, embedded in an anisotropic multilayered medium     

A simple technique for calculating the propagation dispersion ofmulticonductor transmission lines in multilayer dielectric media

A multiconductor transmission line in a multilayer dielectric medium is complicated and therefore is frequently analyzed by the simple quasi-TEM (transverse electromagnetic) approach. Unlike the full wave eigenvalue approach, the quasi-TEM approach does not give the propagation dispersion characteristics of the line. This work overcomes this problem by first obtaining the solution of each multiconductor mode from the quasi-TEM approach. Then these solutions are used as both basis and testing functions in a variational formulation of the full wave eigenvalue analysis. The result is high accuracy in the dispersive propagation constants of the multiconductor modes. By solving only for high frequency eigenvalues, not for the high frequency eigenvectors, the method is simpler and faster than the conventional full wave dispersion analyses     

Gain optimization of a near-field focusing array for hyperthermiaapplications

A variation of the array gain optimization problem has arisen in the study of microwave arrays used for hyperthermia, the heating of biological tissue. For a given array configuration and arbitrary medium it is desired to maximize the power deposition at a prescribed focus in the near field of the array. The authors show how the optimum excitation can be found by solving an eigenvalue problem. Their optimum solution is compared with two other solutions, namely a closed-form solution which optimizes the power in one linear polarization of the radiated field, and a solution based on the popular conjugate-field scheme     

Electromagnetic response of a thin layer

The detectability of a thin layer within a stratified medium is considered. The two limiting cases of a resistive and a conductive sheet are discussed for both TM (transverse magnetic) and TE (transverse electric) excitation. It is shown that the resistive sheet is only `visible? for the TM excitation.     

Generalized pencil-of-function method for extracting poles of an EMsystem from its transient response

A generalized pencil-of-function (GPOF) method is developed for extracting the poles of an electromagnetic system from its transient response. The GPOF method needs the solution of a generalized eigenvalue problem to find the poles. Subspace decomposition is also used to optimize the performance of the GPOF method. The GPOF method has advantages over the Prony method in both computation and noise sensitivity, and approaches the Cramer-Rao bound when the signal-to-noise ratio (SNR) is above threshold. An application of the GPOF method to a thin-wire target is presented     

Power Transmission Through General Uniform Waveguides

The problem of transmitting electromagnetic power through a dissipative waveguide in an optimal fashion is examined. At any frequency the problem is reduced to a weighted eigenvalue problem in which the maximum efficiency appears as the eigenvalue and the required excitation is specified by the corresponding eigenvector. Numerical results are presented.     

Design of IIR digital filters based on eigenvalue problem

This paper presents a new method for designing IIR digital filters with optimum magnitude response in the Chebyshev sense and different order numerator and denominator. The proposed procedure is based on the formulation of a generalized eigenvalue problem by using Remez exchange algorithm. Since there exist more than one eigenvalue in the general eigenvalue problem, we introduce a very simple selection rule for the eigenvalue to be sought for where the rational interpolation is performed if and only if the positive minimum eigenvalue is chosen. Therefore, the solution of the rational interpolation problem can be obtained by computing only one eigenvector corresponding to the positive minimum eigenvalue, and the optimal filter coefficients are easily obtained through a few iterations. The design algorithm proposed in this paper not only retains the speed inherent in the Remez exchange algorithm but also simplifies the interpolation step because it has been reduced to the computation of the positive minimum eigenvalue. Some properties of the filters such as lowpass filters, bandpass filters, and so on are discussed, and several design examples are presented to demonstrate the effectiveness of this method     

Solution of the nonlinear eigenvalue boundary-value problem for tm electromagnetic waves propagating in a Kerr-nonlinear layer by means of the cauchy problem method

The problem of propagation of TM electromagnetic waves in Kerr-nonlinear layer is considered. The problem is reduced to the solution of a nonlinear eigenvalue boundary-value problem for a system of two ordinary differential equations. A numerical method is proposed for solving the considered eigenvalue boundary-value problem. It is shown that the proposed method makes it possible to investigate more complicated types of nonlinearity. Numerical results are reported. The method is compared to another known technique and to the linear case.     

Modeling resistive strips with finite elements for TE polarization

A formulation for modeling RF scattering from infinitely thin resistive strips is developed for TE_z polarization (H-polarisation). finite-element frequency-domain approach using the Galerkin weak form and special gap elements is employed. The resistive strips can be tapered, and immersed in an arbitrary inhomogeneous dielectric/magnetic medium. This formulation has been integrated into an existing finite-element code, and results are given. These results compare well to moment-method solutions     

3-D numerical mode-matching (NMM) method for resistivitywell-logging tools

A three-dimensional (3-D) numerical mode-matching (NMM) method is presented for Poisson's equation in general inhomogeneons media. It reduces the original 3-D problem into a series of two-dimensional (2-D) eigenvalue problems plus a one-dimensional (1-D) layered medium problem, which can be modeled efficiently by a recursion procedure. The algorithm is tested for several 3-D inhomogeneous media and an excellent agreement between the NMM and analytical solutions is obtained for all test cases. We demonstrate some typical applications of the 3-D NMM algorithm in resistivity well logging, including invasion zones of noncircular shape, vertical and horizontal fractures, and horizontal wells. The solution procedure proposed is directly applicable to wave propagation in 3-D inhomogeneous media     

Parameter estimation of autoregressive signals in presence of colored AR(1) noise as a quadratic eigenvalue problem

In this paper, we consider the problem of parameter estimation of autoregressive (AR) signals from observations corrupted with colored AR(1) noise. The proposed method is based on Yule-Walker equations. We express these equations as a quadratic eigenvalue problem and then the parameters of the signal and noise are estimated by solving this eigenvalue problem. We also apply the proposed method to the problem of sinusoidal frequency estimation in colored noise. The performance of the proposed algorithm is evaluated by computer simulation examples.     

膜电阻作为微波电路封装谐振模式抑制层

通常将微波电路置于金属封装之内.如果该封装波导谐振模恰好位于电路工作频率范围之内,电路与封装谐振模间的耦合将干扰电路的工作.在腔内放入覆有膜电阻的介质基片,可以有效地削弱封装谐振模,避免了放入吸波材料的传统方法给军用、宇航用毫米波电路带来的可靠性和机械加工难题.膜电阻的吸波性能取决于膜电阻方阻值和介质层厚度,使用数值方法计算得到应用该方法削弱后的最低阶封装谐振模的品质因数.