Transverse Propagation in Dielectric Waveguide Array

Transverse propagation eigen equations for dielectric waveguide array (DWA) are derived and eigen solutions can be uncoupled into TE and TM modes. Numerical results shows that much stronger space harmonic interaction exists so that a series of interesting physical effect of canonical two-dimensionally periodic (2DP) medium can obviously be observed in DWA and related devices can be predicted, designed and realized much easier.     

介质波导阵列的横向传播特性分析

根据已提出的有关二维周期介质严格分析理论，针对介质波导阵列进行了大量的数值计算。对介质波导阵列中波的横向传播作了详细分析。首先，在给定纵向波矢量(k)的情况下，分析了在不同工作频率时的横向波矢量间布里渊区色散特性，对空间谐波的相互作用情况也进行了研究。其次，在给定工作频率的情况下，分析了不同纵向波矢量和不同调制系数时的横向波矢量间布里渊区色散特性。由于空间谐波的相互作用随纵向波数或调制系数的增大而增强，导致阻带能明显地表现出来，从而使介质波导阵列的横向传播特性能较为全面地得到分析。     

Longitudinal Wave Propagation in Dielectric Waveguide Array

Based on the established rigorous theory for two-dimensionally periodic (2DP) medium, Longitudinal propagation in Dielectric Waveguide Array (DWA) was analyzed in detail. Firstly, given longitudinal wave vector (k _z), Brillouin dispersion relations between transversal wave vectors were analyzed. Interactions between space harmonics were also studied. Secondly, on condition that transversal wave vector k _x equaled k _y, dispersion relations between longitudinal and transversal wave vectors were analyzed in detail. Because of interactions between space harmonics increasingly getting stronger with k _z or modulation coefficients increasing, stop-bands could be distinctly displayed and thus longitudinal propagation in DWA could be comprehensively analyzed. The applications about longitudinal propagation in DWA were also discussed.     

介质波导阵列电磁特性分析

根据已提出的二维周期介质严格理论,比较详细地分析和研究了介质波导阵列的电磁特性．首先,对存在纵向波传播时(kz≠0)的空间谐波相互作用特征进行了分析,得出了横向波传播色散特性．其次,在横向平面上的两互相垂直方向的波数相等(kx=ky)时,对不同波频率下空间谐波相互作用特性及其产生的阻带分布特征作了详细研究,并对横向纵向波传播色散关系进行了分析和计算．最后,得出介质波导阵列存在纯纵向导波的十分有意义的结论,具有实用价值．     

Rugorous analysis of planar waveguides with two-dimensionally periodic layer

Rigorous analysis of planar waveguides with two-dimensionally periodic (2DP) layer is presented. Characteristic solutions in periodic layer are exactly represented by a double Fourier series known as the Floquet solutions. The vector amplitudes of space harmonics are proved to be governed by five-term recurrence relation in the operator-vector form for sinusoidal modulation. A general transmission-line network representation of two-dimensionally periodic medium and multiport network representation of uniform-periodic-medium interface are introduced. Any layered structures cascading with periodic ones can be analyzed. Numerical results based on the established theory are also presented to illustrate characteristics of 2DP medium and structure.     

General theory of doubly periodic arrays over an arbitrary finite field and its applications

A general theory of doubly periodic (DP) arrays over an arbitrary finite field GF(q)is presented. First the basic properties of DP arrays are examined. Next modules of linear recurring (LR) arrays are defined and their algebraic properties discussed in connection with ideals in an extension ringtilde{R}of the ringRof bivariate polynomials with coefficients in GF(q). A finitetilde{R}-module of DP arrays is shown to coincide with thetilde{R}-module of LR arrays dermed by a zero-dimensional ideal intilde{R}. Equivalence relations between DP arrays are explored, i.e., rearrangements of arrays by means of unimodular transformations. Decimation and interleaving of arrays are defined in a two-dimensional sense. The general theory is followed by application to irreducible LR arrays. Among irreducible arrays,M-arrays are a two-dimensional analog ofM-sequences and may be constructed fromM-sequences by means of unimodular transformations. The results of this paper are also important in studying properties of Abelian codes.     

Purely Longitudinal Guidance in Dielectric Waveguide Array

Rigorous analysis shows that independent longitudinally guided TE and TM modes are possible in dielectric waveguide array (DWA) as a two dimensionally periodic medium. Especially, purely longitudinally guidance is also possible and investigated in detail.     

The Convergence of the Eigen Equation for Dielectric Waveguide Array

The eigen equation for Dielectric Waveguide Array (DWA) established by [1] was discussed. The convergence of the eigen equation was also analyzed in detail. Numerical results for a particular rectangular DWA was presented. Compared with those obtained by previous different ways, faster convergence for the eigen equation was reached easily. The characteristics of the eigen equation for DWA was particularly useful in computer propramming and engineering.     

Effects of AM-to-PM Conversion of TV Transmitter on Video Signals

Incidental phase modulation caused by AM-to-PM conversion (carner phase shift) of RF amplifier degrades the detected video signal performance. Its effects are known to be different for different types of demodulators as well as for different signal types to be incidental phase modulated. This paper shows a simple and general analysis for any form of AM-to-PM conversion using derivative form and supposing the video signal to be relatively small. From the analysis, it can be seen how the video-to-video frequency response varies and how much of the lower sideband (LSB), once filtered, will emerge with respect to the amount of AM-to-PM conversion. The general equation to predict the differential phase (DP) and differential gain (DG) degradation caused by AM-to-PM conversion is presented, from which it is shown that there are special AM-to-PM conversion cases that cause no DP and/or DG degradation.     

The Amplitude of Longitudinal Characteristic Modes in Dielectric Waveguide Array

It's not adequate to just obtain eigenvalue for solving eigenvalue problem. Since the eigenvalues associated with longitudinal characteristic modes in dielectric waveguide array (DWA) has been studied, the paper concentrates on the corresponding eigenvector, namely, the amplitude of these characteristic modes. Through numerical study of the amplitude of longitudinal guided TE and TM modes in DWA, space harmonic (SH) coupling and energy conversion effect have been discovered. The paper not only contribute to deep understand the mechanism of SH interaction, but also do good to analyze the resonance, radiation problem in DWA.     

A 14-bit current-mode ΣΔ DAC based upon rotated dataweighted averaging

A new dynamic element matching (DEM) algorithm, referred to as rotated data weighted averaging (RDWA), is implemented in a third-order ΣΔ digital-to-analog converter (DAC) with 64× oversampling and a conversion bandwidth of 25 kHz. The systematic and random errors are considered in the design of the 14-bit converter. The ΣΔ DAC is fabricated in a 2-μm CMOS process and includes the on-chip reconstruction filter. The prototype was designed to test the performance of the DAC without DEM, with data weighted averaging (DWA), and with RDWA. The results show that the new RDWA algorithm is capable of achieving first-order noise shaping while eliminating the signal-dependent harmonic distortion present in DWA     

Characteristic Electromagnetic Fields in Dielectric Waveguide Array

Based on the modal solution of one dimensionally periodic structure with piecewise uniform dielectric constant distribution, characteristic solutions for two dimensionally Dielectric Waveguide Array (DWA) are rigorously formulated. By satisfying periodic boundary conditions in the interfaces inside a unit cell, semi-closed-form dispersion relation for DWA can be established. Numerical results are presented and compared with a previous method. A class of guidance and radiation problems can be solved with much more simplicity and accuracy.     

Nonlinearity correction for multibit /spl Delta//spl Sigma/ DACs

This paper presents a digital correction technique for wide-band multibit error-feedback (EF) digital-to-analog converters (DACs). The integral nonlinearity (INL) error of the multibit DAC is estimated (on line or off line) by a calibration analog-to-digital converter (CADC) and stored in a random-access memory table. The INL values are then used to compensate for the multibit DAC's distortion by a simple digital addition. The accuracy requirements for the error estimates are derived. These requirements can be significantly relaxed when the correction is combined with data-weighted averaging (DWA). Simulation and discrete-component measurement results are presented for a fourth-order 5-bit EF DAC. The results show a 14-bit DAC operating at an oversampling ratio of 8, which is suitable for digital subscriber line applications. The correction uses simple digital circuitry and a 3-bit CADC enhanced by DWA.     

输入缓冲结构ATM交换网络的窗口接入机理研究

本文了输入缓冲结构ＡＴＭ交换网络的窗口接入机理，首先分析了一种传统的相关窗口接入（ＤＷＡ）机理的最大吞吐率性能，然后，提出了一种独立的窗口接入（ＩＷＡ）机理，ＩＷＡ能彻底消除采用传统的ＤＷＡ机理时在输入缓冲器窗口中存在的队头阻塞现象，借助于概率母函数的方法分析了采用该ＩＷＡ机理的输入缓冲ＡＴＭ交换网络的时延和吞吐率性能，给出了求解平均信元时延和最大吞吐率的封闭显式，分析表明，ＩＷＡ机理的性能比传统     

Rigorous Analysis of Electromagnetic Wave Propagation in Cylindrical Dielectric Waveguide Array

Cylindrical Dielectric Waveguide Array(CDWA) should be considered as a kind of two-dimensionally periodic(2DP) medium. Based on the established rigorous theory for 2DP medium, a great amount of numerical results for CDWA were presented. Wave propagation in CDWA was analyzed in detail in this paper. Firstly, given the longitudinal wave vector (k _z=0), Brillouin dispersion relations between transverse wave vectors were analyzed when modulation coefficients or the rate of different dielectric areas in a unit cell varied. Interactions between space harmonics were also studied. Secondly, when the area of dielectric cylinder in the unit cell varied within a given range, CDWA dispersion relations were compared with Rectangle Dielectric Waveguide Array's, some interesting conclusions were obtained.     

OFDM通信系统中的一种通用的信道估计模型

本文根据DFT的一个性质为OFDM通信系统构造了一种通用信道估计模型。该模型利用系统子信道中的一部分专门进行信道估计,适用于慢消失信道。该模型同最小平方差（LS）和最小均方差（LMMSE）相结合分别形成两种信道估计方法,并从理论角度分别分析它们的计算复杂性和均方差性能。对多径信道仿真表明,基于LS的方法误符号率性能比基于LMMSE的方法差2－3dB,但是计算复杂度较低。总之,此信道估计模型的计算复杂度和性能随着用于信道估计的子信道数目增加而增加,当所用子信道数目是周期头长度的两倍时,达到计算量和估计性能的最佳平衡。     

A Two-Dimensional Spectrum Model for General Bistatic SAR

This paper derives a 2-D spectrum model for general bistatic synthetic aperture radar (SAR). By introducing some new parameters such as equivalent monostatic parameters, bistatic factor, and weighted-equivalent range, the 2-D spectrum of general bistatic SAR can be expressed in the form of monostatic SAR even when the transmitter and receiver move along unparallel trajectories with different velocities. The result formulates bistatic SAR into an equivalent monostatic SAR model and would be useful for developing efficient bistatic SAR algorithms in frequency-domain or hybrid-domain processing. Simulation results are given to validate the performance of the model. For special bistatic SAR configurations, the model can be simplified. Compared to other similar models, the proposed model is clearer and much more concise.      

All silica S-band double-pass erbium-doped fiber amplifier

Double-pass (DP) and single-pass (SP) erbium-doped depressed cladding fiber amplifiers designed for S-band operation are evaluated under changes of the input optical power, pumping power, and fiber bending radius. The DP configuration employs the usual combination of a circulator and a Faraday rotator mirror while the SP is based on the copropagating scheme. The amplifiers were characterized in terms of gain and noise figure. It is demonstrated that the DP topology shows much improved gain performance compared to the SP configuration although the noise figure is slightly degraded by counterpropagating amplified spontaneous emission.     

General theory of Maxwell-Garnett model for particulate composites with bi-isotropic host materials

A self-consistent derivation is given for the Maxwell-Garnett model for a very general particulate composite. The bi-anisotropic inclusions are supposed to be randomly embedded in a bi-isotropic host medium. It is seen that the effective medium is also bi-anisotropic in general.     

General direction-of-arrival tracking with acoustic nodes

Traditionally, in target tracking, much emphasis is put on the motion model that realistically represents the target's movements. We first present the classical constant velocity model and then introduce a new model that incorporates an acceleration component along the heading direction of the target. We also show that the target motion parameters can be considered part of a more general feature set for target tracking. This is exemplified by showing that target frequencies, which may be unrelated to the target motion, can also be used to improve the tracking performance. In order to include the frequency variable, a new array steering vector is presented for the direction-of-arrival (DOA) estimation problems. The independent partition particle filter (IPPF) is used to compare the performances of the two motion models by tracking multiple maneuvering targets using the acoustic sensor outputs directly. The treatment is quite general since IPPF allows general type of noise models as opposed to Gaussianity imposed by Kalman type of formulations. It is shown that by incorporating the acceleration into the state vector, the tracking performance can be improved in certain cases as expected. Then, we demonstrate a case in which the frequency variable improves the tracking and classification performance for targets with close DOA tracks.